Illumination Guidelines for Nighttime Highway Work (2003)

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SECTION TWO ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK

SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-3 CHAPTER 1 INTRODUCTION AND RESEARCH APPROACH INTRODUCTION The objective of this research effort was to develop illumi- nation guidelines for nighttime highway work. Nighttime high- way work operations are becoming more common because of the need to avoid daytime congestion and traffic delays. The quality of the work area lighting is a major factor influenc- ing project safety, work efficiency, and work quality. Although lighting standards exist for other industries, no national guide- lines have existed for the illumination of nighttime high- way work. RESEARCH APPROACH Literature Review and State of Current Practice A comprehensive literature review was performed to obtain the most up-to-date and relevant information concerning the illumination of construction work zones. Very few publica- tions were found that dealt directly with lighting for construc- tion work. However, much information was found concerning the general subject of lighting work areas. Additionally, an industry survey was conducted to learn the state of current practice. Field Reviews A number of field visits were made to investigate the cur- rent nighttime highway construction and maintenance prac- tices. The selection of projects was based on their geograph- ical location and diversity, substantial experience with night work, and utilization of different construction practices (e.g., use of screens and barriers to avoid glare). In selecting proj- ects, not only was an effort made to select representative kinds of typical highway projects, but care was taken to avoid repetition and a variety of projects covering nearly all the operations were chosen. A field review form was prepared to record all relevant information as observed on site. The form included pertinent information such as project information and location; tasks information, lighting equipment, and configuration; quantity of light and illumination levels; uniformity, direction, and glare of light; and general information about workers and power sources. During field reviews, several projects with different night- time operations were visited. These reviews included proj- ects in rural, urban, and semi-urban environments on limited access, primary, and other types of roadways. Various types of operations included replacing concrete barrier walls to separate traffic from work zone; asphalt concrete paving of intersections; in-situ concrete construction of bridge decks; excavation, filling, and embankment construction; and milling, repaving, and marking of limited-access highways. Projects were visited in the following locations: Jacksonville, Florida; Orlando, Florida; Tampa, Florida; Gainesville, Florida; Los Angeles, California; Dallas, Texas; Charlotte, North Carolina; Buffalo, New York; Harrisburg, Pennsylva- nia; Grand Rapids, South Dakota; and Salt Lake City, Utah. Various tasks identified were related to all the observed operations. Other information such as background reflectance, importance and speed required, and seeing distance for the tasks were collected. The most difficult and fatiguing tasks in each operation were also identified. Most of the observed tasks had low or medium background reflectance owing to low reflectivity of the pavement and other concrete and soil structures. Importance, speed, and accuracy of the tasks also varied from low for excavation to high for paving and fin- ishing works. Seeing distances of the tasks were categorized into four main categories: (1) less than 0.31 m (1 ft); (2) 0.31 to 1.5 m (1 to 5 ft); (3) 1.5 to 4.6 m (5 to 15 ft); and (4) more than 4.6 m (15 ft). For construction lighting, equipment-mounted lights, portable light plants, and their combinations were most commonly used. Some equipment such as pavers and rollers were equipped with custom-made retrofit lights. Pavers usually had six or more lights: two lights at the front, two lights at the rear, two lights aiming at the screed, and the rest of the lights illuminating the sides of the equip- ment. Figure 1 shows a typical pavement roller in use on a Charlotte, North Carolina, project site. Compacting rollers and brushing rollers usually had two to four sealed lamps and sometimes additional mounted lights. However, wheel loaders, dump trucks, and flat-beds were equipped with manufactured conventional equipment lights. For bridge deck construction, the crane, conveyor system, and screed were equipped with several mounted lights. Milling

2-4 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK machines had sealed beam units, which were manufactured and installed at the factory. Relatively stationary work zones were usually supplemented by portable light plants, which were also used for general lighting of the area. Most of the mounted lights were 500-W tungsten-halo- gen lamps powered by diesel generators. The generators, in most areas, were installed on the construction equipment. These halogen lights were mounted on custom-made brack- ets and poles and provided sufficient flexibility to change lamp height and aim as desired. Figure 2 shows a typical asphalt paver operating with contractor-installed auxiliary lighting. Most of the fixed lights were 75- to 100-W conventional automobile lamps and had fixed aim and light positions. The most common portable light found during field reviews was a light trailer equipped with four high-intensity dis- charge (HID) lamps of 1,000 W each. Trailers were also equipped with diesel generators and 9.2 m (30 ft) maximum height adjustable towers. These light plants used metal halide, one of the most common lamps enclosed in a para- bolic reflective cover to provide a uniform narrow beam of light. These light towers provided sufficient uniform flood light for the work zone; however, in some instances, they also caused severe discomfort glare and sometimes disabil- ity glare to the motorists, especially when installed against the moving traffic. Figure 3 shows a typical portable light plant tower. For the bridge deck construction project, the concrete barge and chute were illuminated with 1,000-W sodium vapor lamps enclosed in a rectangular reflective covering. Lights on the crane were 1,000-W metal halide lamps spaced at 9.2 m (30 ft) and oriented toward the hoist. For the milling-repaving project, lights on the milling machine were fixed and oriented to illuminate the critical areas such as the conveyor, milling edge, and rear and all sides of the equipment. Quantity of light was found to be sufficient for most of the tasks; however, some tasks were not adequately illuminated, and reasons for this were attributed partly to the inadequacy of light plants and partly to their improper orientation. Par- ticularly for compacting rollers, lighting was not sufficient and the operator was moving the equipment broadly in a pat- tern based on experience instead of vision. Similarly, illumi- nance levels were not enough for sweeping brush rollers and asphalt spreaders applying tack coats. The operators essen- tially moved in a certain predefined pattern and sometimes failed to notice missed spots. For intersection paving and bridge construction jobs, illuminance levels for hand spread- ing of the mix also were less than satisfactory. In most cases, illumination of the general area was found to be adequate; Figure 1. Pavement roller operation (Charlotte, North Carolina). Figure 2. Typical paver operating with contractor- installed lighting (Buffalo, New York). Figure 3. Typical portable light plant tower.

however, in many cases, task illumination was not ade- quately emphasized. Factors that were observed to evaluate quality of light included uniformity, direction, diffusion, and direct and veiling glare. Lighting for nearly all the observed opera- tions was adequately uniform. In the milling and repaving operation, uniformity of light was difficult to maintain because of the continuous movement of the operation. Good uniformity was possible with the use of well-dif- fused luminaires. Regarding flood light towers, light was well diffused and uniform as compared with equipment- mounted lights, which provided more spot and task illumi- nation. The direction of lighting was found objectionable in many cases, particularly for tower lighting plants. In one case, the plant was placed in close proximity to the travel lane facing oncoming traffic, the result of which was nearly blinding dis- ability glare to the motorists. In other cases, light plants were situated at locations creating a shadow zone on the tasks. Because of inappropriate directivity of lights, on several occasions tasks were performed in a negative contrast instead of a positive one. Shadows of defects aided their identifica- tion. Spotlights mounted on various equipment, in general, had better directivity. Lights on some of the compaction rollers were not mounted high enough; as a result most, of the light fell on the wheels instead of the pavement. Spot- lights on milling machines were factory installed and had better directivity. Veiling glare was negligible for all the observed opera- tions because of the low reflectivity of pavement and other construction surfaces. Direct glare to workers was, in gen- eral, more common in the case of highway operations than for bridge construction. The problem of glare to motorists was found to be acute for highway operations in which adja- cent lanes were opened to traffic. In urban and semi-urban environments, particularly where roadway lights were avail- able, there were fewer glare problems because there was reduced background contrast. It was noted during field inves- tigation that lighting design and provision were essentially based on the contractor’s discretion and, in some cases, little or no thought was given to location, positioning, and orien- tation of the light plants. Summary of Survey A preliminary list of construction and maintenance tasks was identified and sent to all the SHAs. In the survey, respon- dents were asked to identify the construction and mainte- nance tasks performed in their states during nighttime. They were also asked to indicate the frequency of these nighttime tasks. Out of 52 agencies, a total of 33 responded, of which 28 respondents indicated some nighttime construction and maintenance work in their states. SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-5 APPROACH TO DEVELOPMENT OF ILLUMINATION REQUIREMENTS Identification and Classification of Nighttime Work Activities In order to categorize typical highway nighttime work, various highway operations were identified. Interviews with DOT personnel, opinions of various knowledgeable individuals, and review of standard specifications for road and bridge construction resulted in a preliminary list of the most commonly performed highway operations (1). These operations were categorized into highway maintenance and highway construction tasks. Both lists also included activities on bridges, signalization, and other highway facilities. A brief description of these tasks is presented in Table 1. The tasks in each list represent various operations and activities, which are categorized according to their similarities in visual requirements. Table 2 shows some of these task categories, typical oper- ations represented by them, and various activities involved in the operation. Although all the activities in a particular oper- ation (as shown in Table 2) may not have similar visual requirements, they are grouped together for practical reasons. Compliance is more realistic if a single lighting standard is specified for one operation rather than a different standard for each activity in the operation. However, the task category representing several operations is based on the similarity of visual requirements of those operations. The results of responses obtained from the survey regard- ing construction and maintenance tasks during nighttime are summarized in Tables 3 and 4, respectively. Tables 3 and 4 give the relative frequency of night work as reported by SHAs. To identify the most commonly performed mainte- nance and construction tasks, both the lists are sorted in a decreasing order of the task frequency. Resurfacing, barrier wall placement, milling, and pavement marking appear to be the most common construction tasks performed at night. On the other hand, traffic signaling, lighting systems, landscap- ing, riprap, and sidewalks are the least preferred tasks for nighttime construction. Table 4 shows cleanup, concrete pavement repair, and bridge deck rehabilitation as frequent maintenance activities during nighttime. In the survey, many respondents indicated that a significant amount of nighttime maintenance is attrib- uted to emergency work in addition to regular required main- tenance. Earthwork, landscaping, and rip rap are the least common maintenance activities conducted at night. Factors Influencing Illumination Requirements Identification of Key Factors From literature review and discussion with experts on lighting and illumination, a number of factors affecting

illumination requirements were identified. During the process of identification, only those factors that are related with outdoors and nighttime highway type situations were selected. They are categorized in four categories, which include: 1. Human factors, 2. Environmental factors, 3. Task-related factors, and 4. Lighting factors. Further classification was done for the task-related factors because of their varying characteristics. Figure 4 summarizes all the factors and categories. These categories are explained in greater detail in the following sections. Human and Cognitive Factors Visibility detection and recognition are greatly affected by various human physical, physiological, and psychological factors. The important human factors affecting vision and perception are as follows: 1. Age, 2. Visual acuity, 3. Response characteristics, 4. Attention, 5. Expectation, 2-6 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 6. Experience, and 7. Familiarity. Many studies have indicated that there is a correlation between age and visual acuity. Ability to detect targets tends to decrease for the observers belonging to a older age group. Similarly, the effect of visual acuity, which is in- fluenced by several human visual functions such as glare sensitivity and transient adaptation, on an individual’s perception and recognition varies depending on the indi- vidual’s age. On the other hand, response characteristics and cogni- tive behavior of an individual’s experience and familiarity with a particular object also affect the process of recog- nizing and perceiving that object. For example, an experi- enced operator can identify defects on a newly paved road surface even under reduced illumination levels as com- pared to one having less experience with the work envi- ronment. Environmental Factors In this category, factors such as weather conditions, fog, surface condition, and ambient brightness are included. The literature review indicated that ambient brightness helps reduce the relative contrast of the object and the background, which is crucial in detecting an object. However, for night work conditions, ambient brightness helps increase the illu- Task No. Maintenance Tasks Performed at Night Construction Tasks Performed at Night 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Maintenance of earthwork/embankment Reworking shoulders Barrier wall or traffic separator Milling and removal Resurfacing Repair of concrete pavement Crack filling Pot filling Surface treatment Waterproofing/sealing Sidewalks repair and maintenance Riprap maintenance Resetting guardrail/fencing Painting stripes/pavement markers Landscaping/grassing/sodding Highway signing for maintenance works Traffic signals maintenance Highway lighting system—repair and maintenance Bridge decks rehabilitation and maintenance Drainage structures maintenance and rehabilitation Sweeping and cleanup Excavation—regular, lateral ditch, channel Embankment, filling and compaction Barrier walls, traffic separators Milling and removal Resurfacing Concrete pavement construction Subgrade stabilization and construction Base courses—clay, cement, asphalt Surface treatment Waterproofing/sealing Sidewalks construction Riprap placement Guardrail/fencing Painting stripes/pavement markers/metal buttons Landscaping/grassing/sodding Highway signing for construction Traffic signal construction Highway lighting system construction Bridge decks construction Drainage structures, culverts and sewers construction Construction of other concrete structures TABLE 1 Highway maintenance and construction tasks performed at night

mination level of the task and requires less additional light for adequate illumination. Atmospheric losses may have a significant effect upon the illuminance at the observer’s eye level unless the view- ing distance is short. In fog, the law of diminishing returns takes effect at relatively short distances. Since for nearly all the highway construction and maintenance work, distances are relatively short and the visual field is more or less lim- ited to the work zone, weather conditions and atmospheric losses may not contribute significantly to the losses in object visibility. Task-Related Factors Task-related factors, owing to their characteristics and variations, are further subcategorized into the following five categories. SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-7 Equipment Attributes. Use of different types of construc- tion equipment adds another dimension to nighttime highway work compared with other external night work situations. Factors related to construction equipment influencing task illumination requirements include: 1. Speed, 2. Physical characteristics, and 3. Response time. Speed of equipment governs the exposure time or the duration of seeing. To some extent, higher speed of a par- ticular piece of equipment can be compensated for by increased illumination for adequate visibility. Physical characteristics of some equipment may restrict the vision of the operator, and some of the targets may not be detectable irrespective of the quantity of illumination. For example, in a roller, the operator’s vision is restricted by Task Category Type of Operation Activities Excavation Regular excavation Subsoil excavation Lateral ditch excavation Channel excavation Embankment Dry fill method Hydraulic method Backfilling Pipe culverts Storm sewers Other structures Subgrade Stabilization of subbase Lime-treated Cement-treated Base Courses Limerock base Graded aggregate base Sand-clay base Shell stabilized base Soil-cement base Asphalt base Composition of mixes Preparation of subgrade Spreading the mix Compacting and finishing Correcting defects and thickness Priming, curing or maintaining Surface Treatment Prime coat Tack coat Preparation of surface Distribution of material Spreading cover material Rolling and curing Cement-Concrete Pavement Sidewalk Subgrade preparation Setting forms Placing reinforcement Placing concrete Consolidating and finishing Straightedging and surface correction Joints and curing Fencing Guardrail Fencing Setting timber and steel posts Placing rail or fabric Reflector elements Highway Lighting Excavation and backfilling Trenches for cable Concrete base for light poles Erecting light poles Installation of luminaires TABLE 2 Categorization of typical highway construction tasks

the presence of drums in the visual field. Similarly, for load- ers and pavers, detection of targets near the equipment is determined by its position. However, for far targets, quantity of illumination increases the detection distance. Required detection distance also depends on the response characteris- tics of the equipment. Equipment with low response time, low maneuverability, or high speeds requires greater detec- tion distance and hence increased illumination. Physical Attributes of the Task. Physical characteristics of the task or the target have significant effects on the quan- tity and quality of illumination required for detection. Size, type, appearance, and reflectance targets and their relation- ship with luminance values for their identification have been discussed in detail in existing literature. Lower luminance levels are required for larger targets. Similarly, location and 2-8 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK level of conspicuousness of the target also helps its identifi- cation. For the same illumination level, detection of any tar- get in the middle of the work zone is faster than the ones on the sides. Minimum distance of seeing a target from the observer’s perspective also affects its identification. A defect on the road surface is more likely to be detected by a ground crew than an operator on the equipment for the same illumination level. Task Qualitative Attributes. The qualitative factors asso- ciated with nighttime highway construction tasks include: • Importance of the task, • Accuracy desired, • Visual difficulty in performing the task, and • Visual fatigue as a result of performance. Frequency of Tasks Task No. Construction Tasks Performed at Night Frequently Occasionally Rarely 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Resurfacing Barrier walls, traffic separators Milling and removal Painting stripes, pavement markers, metal buttons Bridge decks construction Concrete pavement construction Base courses—clay, cement, asphalt Excavation—regular, lateral ditch, channel Embankment, filling and compaction Highway signing for construction Subgrade stabilization and construction Surface treatment Drainage structures, culverts & sewers construction Waterproofing/sealing Construction of other concrete structures Guardrail, fencing Highway lighting system construction Traffic signals construction Landscaping, grassing, sodding Riprap placement Sidewalks construction 7 7 6 4 3 3 3 3 2 2 2 2 1 1 0 0 0 0 0 0 0 8 8 11 8 16 9 6 5 6 6 5 1 5 4 6 4 3 1 0 0 0 12 3 9 4 7 12 8 10 10 8 10 5 13 6 13 5 7 9 9 6 4 Total Number of Responses 28 NOTE: Tasks are arranged in the decreasing order of their frequencies. TABLE 3 Number of states performing various nighttime highway construction tasks

As indicated in the literature review, performance increases with the level of illumination until an optimum level. Beyond this point, further increases do not necessarily deteriorate performance. From the conclusion of previous studies, it can be inferred that visually difficult and visually fatiguing tasks may be performed better with an increase in the illumination level. Similarly, for the tasks requiring higher accuracy and additional attention, increased illumina- tion is desired. Background Factors. Background factors include the char- acteristics of the surface on which a task needs to be performed or a target needs to be detected. Surface brightness, which also depends on background illumination, reduces the positive rel- ative contrast for the task. Particularly when the degrees of reflectivity of the background surface and the task are in the same range, detection and recognition becomes difficult. SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-9 Operation Attributes. These factors are essentially asso- ciated with the type of highway construction operation and the location where it is performed. These factors include: • Type of facility, • Facility environment, • Traffic control, and • Location on the highway. These factors influence task illumination requirements for the same task in varying capacity. Type of facility determines classification of the highway (i.e., limited access highways, other arterials, collectors, or local roads). Any construction or maintenance operation on limited access highways requires increased attention in forms of quality, safety, and traffic control. Glare prob- lems due to excessive illumination are more severe on Frequency of Tasks Task No. Maintenance Tasks Performed at Night Frequently Occasionally Rarely 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Sweeping and cleanup Repair of concrete pavement Bridge decks rehabilitation and maintenance Resurfacing Milling and removal Highway lighting system—repair and maintenance Traffic signals maintenance Painting stripes/pavement markers Surface treatment Barrier wall or traffic separator Crack filling Pot filling Resetting guardrail/fencing Waterproofing/sealing Highway signing for maintenance and works Drainage structure maintenance and rehabilitation Sidewalks repair and maintenance Reworking shoulders Riprap maintenance Landscaping/grassing/sodding Maintenance of earthwork/embankment 7 6 4 3 2 2 2 2 2 1 1 1 1 1 0 0 0 0 0 0 0 8 2 4 7 8 8 7 5 1 4 3 3 3 2 3 3 2 1 1 1 0 3 12 8 9 7 4 7 7 2 8 6 5 3 3 11 3 3 6 5 3 7 Total Number of Responses 27 TABLE 4 Number of states performing various nighttime highway maintenance tasks

FACTORS INFLUENCING TASK ILLUMINATION REQUIREMENTS ENVIRONMENTAL FACTORS HUMAN FACTORS TASK-RELATED FACTORS LIGHTING FACTORS Age Visual Acuity Response Characteristics Experience & Familiarity Weather Conditions Fog / Dust Smoke Wet / Dry Surface Ambient glare & brightness Geometric Relationships Orientation Power of Lamps Gradient Uniformity EQUIPMENT ATTRIBUTES Speed Physical Characteristics Response Time TASK PHYSICAL ATTRIBUTES Type of Target Size of Target Appearance & Reflectance Location & Conspicuity Seeing Distance TASK QUALITATIVE ATTRIBUTES Importance of Task Accuracy Required Visual Difficulty Visual Fatigue BACKGROUND FACTORS Reflectivity of Surface Surface Brightness OPERATION ATTRIBUTES Type of Facility Facility Environment Traffic Control Location on Highway Figure 4. Summary of factors influencing task illumination requirements.

these highways because the speed of vehicles is higher and drivers do not expect any interference. Facility environ- ment includes the geographical area of the operation such as urban, semi-urban, or rural. For urban areas, street lights and roadway lighting may provide sufficient illumination to perform common highway construction tasks. The prob- lem of glare is also limited in the urban areas because of considerable ambient brightness. However, for rural areas, adaptation and glare are serious problems because of the sudden shift from darkness to a brightly lit environment and then back to darkness for motorists passing through the work zone. Illumination requirements for highway operations are also affected by the traffic control plan designed for the operation. Complete road closure or detour for bridge or highway construction may eliminate the problem of glare to the motorists. Similarly, traffic control plans may depend on the duration of the project. For example, a short- term project may need different types of lights and illumi- nation levels than a long-term project. Location of the work area on the highway or bridge, such as on the right- of-way, median, shoulder, ramp, or intersection, also affects the illumination specification and requirements. Since reflectivity of the background surface depends on the location on the highway, illuminance values to facili- tate detection of a target may vary with the location of the task. Therefore, illuminance values for gravel shoulder, asphalt pavement, concrete pavement, and concrete deck are different and vary with the distance from the lamp. As a result, illuminance values for the same surface luminance will be different. Lighting Factors Factors associated with lighting provisions that can influ- ence task illumination requirements include: 1. Geometric relationship, 2. Orientation, 3. Power and type of lamps, 4. Gradient uniformity, and 5. Glare. Geometric relationships among light plant, observer, and location of the object sometimes affect the amount of illumination required because the reflectance of back- ground surfaces varies with different positions. Similarly, orientation, power, and types of lamps also affect reflectance and contrast. Uniformity is associated with the quality of illumination, which is important for seeing detail in the work area. Uniformity, depending on the task char- acteristics, also affects the quantity of illumination SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-11 required to perform the task. Glare of both types, discom- fort and disability, is a direct result of the quantity of illu- mination. Glare is not only affected by the power and type of lamps but also by the size and orientation of the light source and the reflectance of the background surface. Identification of Significant Factors From the literature review and discussion with experts on lighting and illumination, the factors affecting illumi- nation requirements have been identified and summarized in Figure 4. Although all of the identified factors influence task illumination requirements, the degree of influence varies. A list of factors that significantly affect the illumi- nance levels for highway construction tasks is given in Table 5. The factors in the table have been selected specif- ically for highway construction-related visual tasks from the factors described in Figure 4 and as a result of the lit- erature review. Selection of these factors was based on (1) their significance as addressed in a number of technical articles pertaining to roadway and outdoor lighting and (2) the practicality of assigning meaningful subjective lev- els. The factors that were not suitable for quantifying were not included in the list since they would have affected the proper comparison of nonhighway and highway tasks. Var- ious measurement levels are assigned to the factors in Table 6. A number of these levels are subjective in nature because it is not feasible to introduce objective levels for all the factors, particularly keeping construction activities in view. There has been no priority or significance level associated with these factors. All the factors in the table are not assigned a significance level or degree of influence although they affect illumination requirements identically and vary in their degree of influence. Some factors are envisaged to have a direct and consistent effect on the light- ing levels required for seeing. These conclusions are drawn from the findings of the literature review and experienced personnel. The primary sources of literature in determining these factors were IES of North America publications and standards. According to one IES publication for industrial lighting, the main factors affecting industrial seeing tasks include: 1. Size of object, 2. Contrast or reflection, 3. Time spent to evaluate and to complete the task, 4. Luminance, 5. Accuracy to be achieved in the task, and 6. Age. Based on the IES recommendations, the following factors were included in the data analysis and model development:

1. Speed associated with the task, 2. Accuracy or importance desired for the task, 3. Reflectance of the background surface, 4. Seeing distance of the object from the observer, and 5. Relative size of object to be seen. None of the human factors is included in the list because of the presumption that every crew or operator is a normal atten- 2-12 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK tive observer in a given age group. Moreover, during field investigation, it was determined that on highway construction projects in general, equipment operators belong to one age group. Visual and other variations among crew members for highway construction work do exist. However, recommended lighting guidelines are based on normal visual capacity with sufficient allowance for individual variation. The factor of time spent on the task has been interpreted as speed associated with Factor Suggested Factor Levels Size of the objects to be seen Shape of the objects to be seen Contrast of object & background Age of workers Reflectance of the surface Time spent in seeing Importance of task Importance of speed Importance of accuracy Visual difficulty in seeing Visual fatigue experienced Seeing distance of the object Safety and glare considerations Importance of uniformity very fine, small, medium, large flat, 1-dimensional, 3-dimensional <30%, 30–70%, >70% <30%, 30–70%, >70% under 40, 40–55, over 55 years few seconds, 1–5 min, half hr + low, medium, high low, medium, high low, medium, high low, medium, high low, medium, high 1–5 ft, 5–15 ft, >15 ft non-critical, moderately important, critical non-critical, moderately important, critical TABLE 5 Factors significantly affecting nighttime highway task visibility Task No. Factors Subjective Levels 1 Importance and accuracy of the task L – Low M – Medium H – High 2 Background reflection L – Low M – Medium H – High 3 N – Not applicable L – Low M – Medium H – High 4 Size of the object to be seen F – Fine S – Small M – Medium L – Large 5 Distance of seeing S – 1 to 5 ft M – 5 to 15 ft H – > 15 ft Speed TABLE 6 Factors influencing task illumination requirements and their subjective levels

possible movement. Hence, it has been substituted by a factor of speed in the list. The dynamic nature of a construction project also introduces the factor of visual distance for the oper- ator and the crew, namely, the seeing distance within the same work zone and for the same task may vary. As a result, another factor on seeing distance has been added to the list. SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-13 For comparison purposes, it was considered necessary to quantify these selected factors. Since determining and assign- ing number values to the factors was found difficult in actual field conditions, certain subjective levels were assigned to these factors from practical considerations. Table 6 provides the factors and their subjective levels.

2-14 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK CHAPTER 2 DEVELOPMENT OF ILLUMINATION REQUIREMENTS ILLUMINANCE LEVEL CATEGORIES The prime requirement for highway construction lighting is to facilitate the performance of construction-related visual tasks in the work zone through high-quality illumination. Correct lighting can enable the crew to observe and effec- tively control various equipment and processes in highway operations. Based on the appraisal of findings, recommenda- tions for illuminance categories and values are provided in Table 7. The three categories, which provide for minimum illuminance levels at 54 lx (5 fc), 108 lx (10 fc), and 216 lx (20 fc) for various tasks, cover the majority of the highway- and bridge-related construction and maintenance operations. Although the recommended levels satisfy safety require- ments, they are also intended to provide a guide for efficient visual performance. For this reason, they may not be inter- preted as recommended requirements for regulatory mini- mum illuminance. Determination of the three categories and their minimum illuminance values was influenced by several considerations. The significant considerations include 1. IES-recommended minimum levels for normal activity from the point of view of safety. For visual detection in high hazard situations, this value is 54 lx (5 fc). 2. IES-recommended levels and uniformity ratios for construction activities, which are 108 lx (10 fc) for general construction and 22 lx (2 fc) for excavation work. 3. Occupational Safety and Health Administration (OSHA)- required minimum illumination intensities for construc- tion industry, which range from 33 lx (3 fc) to 108 lx (10 fc) for various construction activities. Proposed Code of Federal Regulations (CFR) 30 for illumination requirements for draglines, shovels and wheel excava- tors, which range from 54 lx (5 fc) to 108 lx (10 fc) for various parts of the equipment. 4. Provisions for lighting requirements and guidelines as included in various state specifications for highway and bridge work. Minimum of 54 lx (5 fc) in Florida, 108 lx (10 fc) in Michigan, 108 to 216 lx (10 to 20 fc) in North Carolina, and 216 lx (20 fc) in Maryland are some of the provisions. 5. Opinions and views of various experts as obtained from the survey and literature review concerning comfortable and practical minimum illuminance values and cate- gories for nighttime highway work. 6. Experiences of the research team as obtained from the field reviews and interviewing crew personnel. In contrast to IES illuminance ranges and weighting-factor system, the suggested categories in Table 7 recommend only the minimum illuminance values. In 1979, IES shifted from a single-value recommendation to the range system in order to reflect lighting-performance trends found in research. It was intended that the new procedure would allow the designer flexibility in determining illuminance levels depending on lighting task characteristics. The characteristics for lighting tasks included 1. Visual display or details to be seen, 2. Age of the observers, 3. Importance of speed or accuracy for visual performance, and 4. Reflectance of the task and background. The object in the visual display offers some inherent visual difficulty and affects the illuminance value required to per- form the visual task. As pointed out in the findings, the age of the observer reflects the condition of visual system. For typical highway operations, nearly all the crew and equip- ment operators can be classified in one broad age category and, therefore, age is assumed to cause no additional varia- tions on the illuminance values other than the ones selected for that age group. The importance of speed and accuracy depends on the seeing requirements, whether casual, impor- tant, or critical. The reflectance of the object and background in a task determines luminance caused by the illuminance. However, from the analysis of findings it was found that reflectances for various road and other construction surfaces do not vary significantly. As a result, the three recommended categories were found to be adequate to account for differences in visual display and variations in accuracy and speed for the major- ity of the highway construction tasks. Another reason to

SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-15 limit the number of categories or illuminance levels to three is attributed to the feasibility of attaining one or more lev- els in one operation. Category I is recommended for the general illumination in the work zone primarily from the safety point of view in the area where crew movement is expected or taking place. This category is also recommended for tasks requiring low accu- racy, involving slow-moving equipment, and having large- sized objects to be seen. Category II is recommended for illumination on and around construction equipment and the visual tasks associated with the equipment. The primary concern in suggesting the min- imum illuminance value for this category is equipment safety and medium accuracy desired for the task. For certain tasks (e.g., resurfacing), not only is the safety around the paver and roller crucial but quality of the finished surface is also important. Category III is suggested mainly because of the efficient visual performance required for certain tasks. Highway tasks which present higher visual difficulty and require increased attention from the observer include crack and pot- hole filling, joint sealing, critical connections, and tasks involving maintenance of electrical connections and moving mechanical parts. Table 7 includes other examples for each of the three categories. COMPARISON OF NONHIGHWAY AND HIGHWAY WORK TASKS The visual requirements in a typical highway construction task are similar to the visual requirements of certain outdoor industrial tasks. For comparison with highway tasks, a list of equivalent nonhighway tasks was identified and their required illuminance levels were obtained from ANSI/IES recommendations for outdoor industrial spaces (2). Based on the characteristics of these tasks, they were assigned differ- ent levels of the various factors as determined in the earlier section. Table 8 provides the list of selected nonhighway out- door tasks, area, factor descriptions, and recommended illu- minance levels. A statistical analysis of the nonhighway matrix revealed a correlation between the factors and their effect on illumination Category Min. Illuminance Level lx (fc) Area of Illumination Type of Activity Example of Areas and Activities to be Illuminated I general illumination throughout spaces performance of visual task of large size; or medium contrast; or low desired accuracy; or for general safety requirements II 108 (10 fc) general illumination of tasks and around equipment performance of visual task of medium sizes; or low to medium contrast; or medium desired accuracy; or for safety on and around equipment III 216 (20 fc) illuminance on task performance of visual task of small sizes; or low contrast; or desired high accuracy and fine finish 54 (5 fc) • Excavation • Paving • Milling • Concrete work • Crack filling • Pot filling • Signalization or similar work requiring extreme caution and attention • Sweeping and cleanup • Movement area in the work zone • Movement between two tasks • Around paver, miller, and other construction equipment TABLE 7 Recommended minimum illuminance levels and categories for nighttime highway construction and maintenance

levels. The main statistical procedures used were (1) cor- relation coefficients and (2) determination of mean. Cor- relation analysis was performed to examine the extent of the relationship between the selected factors and illumi- nance levels. The accuracy and importance of the factors were given the highest priority during the comparison of nonhighway work tasks with highway work tasks. Nonhighway tasks were matched with equivalent high- way tasks. As a result of the analysis, it was determined that if four or more factors including importance and accuracy match, then the illumination level recommended for the first task may be suggested for the second task also. 2-16 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK DEVELOPMENT OF RECOMMENDED ILLUMINATION CRITERIA Illumination Levels As described in the previous section, a similar assignment of factor levels was also performed for all the identified high- way construction and maintenance tasks. For each of the high- way tasks, four or more factors from the nonhighway matrix were matched. A list of nonhighway tasks was prepared for all highway tasks. An average of illumination levels speci- fied for all matching nonhighway tasks was used to suggest Factors Task No. Area Name of the Activity Importance Reflection Speed Size Distance Recommended Illuminance Level lx(fc) 1 2 3 4 5 6 7 Automotive Industry Frame assembly Welding area Machining operations Coal yards & oil storage Outdoor substation, parking Entrance, truck maneuverability Furnace area, sheet rolling H H H L L L H M H H L L L M L N H N N L N S S F L L L M S S S L L L S 50 50 75 0.5 1.5 5 30 (540) (540) (810) (5.4) (16.2) (54) (324) 8 9 10 Iron & Steel Industry Mold yard Scrap stock yard Hot top storage L M M L M H N N M M M M L L L 5 10 10 (54) (108) (108) 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 Petrochemical Industry Pump rows, valves, manifolds Heat exchangers Maintenance platforms Operating platforms Cooling towers, equipment Furnaces Active ladder, stairs General area Extruders and mixers Conveyors Outdoor plants, equipment Outdoor substation Plant road: Frequent use Plant road: Infrequent use Plant parking lots Outdoor bulk storage Large bin storage Small bin storage Small parts storage L L L L L L L L M L L L L L L L L M M L L L L L L L L M L L L L L L L L M M N N N N N N L N L M N N M L L N N N N M M L M M M L L M L S L L L L L L S F L L L L L L L L M L M M L L L L M M M 5 3 1 5 5 3 5 1 20 2 5 2 0.4 0.2 0.1 0.5 5 10 20 (54) (32.4) (10.8) (54) (54) (32.4) (54) (10.8) (216) (21.6) (54) (21.6) (4.3) (2.2) (1.1) (5.4) (54) (108) (216) 30 31 32 33 34 35 36 37 38 Pulp and Paper Industry Groundwood mill grinder Beater room Roll dryer Cutting and sorting Active warehouse Shipping truck shed Roadways Log pile Log unloading H H H H M M L L L M M M M M M L L L H L M H L L M N L S M S S M M L M M M M M S M M L L M 70 30 50 70 20 20 0.4 3 5 (756) (324) (540) (756) (216) (216) (4.3) (32.4) (54) 39 40 41 42 Industrial Outdoors Excavation General construction Active entrance Inactive entrance L M L L L M L L N N L N L M L M M M L L 2 10 5 1 (21.6) (108) (54) (10.8) TABLE 8 Illuminance levels of outdoor industrial tasks and spaces

illumination categories for highway tasks. Table 8 shows the typical industrial tasks, their factor descriptions, and speci- fied illumination requirements. Suggested illumination values (see Table 9) for highway tasks were based on the following: (1) compared averages of illumination for matching nonhighway tasks; (2) current illu- mination standards and regulations for construction; (3) cur- rent SHA requirements for illumination; and (4) researchers’ observations of current practice on nighttime highway con- struction work. In some cases, the suggested illumination value was less than the compared average illumination for a nonhighway task because of these considerations. In order to recommend guidelines for equipment light- ing, a set of construction equipment most commonly used for highway work was selected. Based on the equipment’s characteristics, its application, and relevant Society of Automotive Engineers (SAE) current practices, a minimum area to be illuminated in front and back of the equipment is recommended. The current SAE-recommended practice J1024 for for- ward lighting on construction and industrial machinery pro- vides for adequate illumination for a distance that exceeds the vehicle stopping distance (D) at its maximum operating speed (3). This stopping distance includes a 1.5-sec operator SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-17 reaction time interval and can be computed by the following formula (where H is the speed): D (ft) = 2.2 H mph D (m) = 0.4167 H km/h The actual stopping distance is a function of machine mass and speed. Braking performance for rubber-tired con- struction machines is provided as a recommended practice in SAE J1142 (3). At typical working speeds on the order of 16.1 to 24.2 km/h (10 to 15 mph), braking distances are approximately 4.6 to 6.1 m (15 to 20 ft) plus the reaction dis- tance of 10.1 m (33 ft). The illuminated area in the direction of travel should, therefore, be approximately 17.7 m (58 ft) ahead and behind the equipment. Although SAE standards do not provide an illumination level for this point, it is esti- mated that at the maximum range, the illumination should be at least 10.8 lx (1 fc). The suggested minimum area to be illuminated for each piece of equipment is presented in Table 10. For practical reasons, most of the equipment is classified in two broad cat- egories: slow-moving equipment and fast-moving equip- ment. Although the illumination level at the maximum range Factors Suggested Illumination Task No. Task Description (Construction) Importance Reflection Speed Size Distance Compared Averages Category Level lx (fc) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 Excavation—regular, lateral ditch, channel Embankment, filling and compaction Barrier walls, traffic separators Milling and removal Resurfacing Concrete pavement construction Subgrade stabilization and construction Base courses—clay, cement, asphalt Surface treatment Waterproofing/sealing Sidewalks Riprap Guardrail, fencing Painting stripes/markers/metal buttons Landscaping, grassing, sodding Highway signing Traffic signals Highway lighting system Bridge decks Drainage structures, culverts, storm sewer Other concrete structures L L M M M M L M M M M M M M L M H H M M M L L M M H H L L H H M M M H L M M M L M H N M N M M L L M M M L L N M N N N N N N L L L M M L M L M L M L M M S L M S S M L M L L L L L L M L L M M M M L L M S M M M L 1.3 0.6 10 10 10 10 1.86 10 10 10 20 17.5 15.7 10 1.3 15.7 43.3 70 10 13.3 10 I I II II II II I II II II II II II II I II III III II II II 54 54 108 108 108 108 54 108 108 108 108 108 108 108 54 108 216 216 108 108 108 (5) (5) (10) (10) (10) (10) (5) (10) (10) (10) (10) (10) (10) (10) (5) (10) (20) (20) (10) (10) (10) (Maintenance) 22 23 24 25 26 27 Maintenance of earthwork/embankment Reworking shoulders Repair of concrete pavement Cracking filling Pot filling Resetting guardrail/fencing L L M H M M L H M M M M M M M L N N L L S F F M L L M M M M 0.6 0.4 10 30 13.3 15.7 I I II III II II 54 54 108 216 108 108 (5) (5) (10) (20) (10) (10) TABLE 9 Suggested illumination categories and levels for typical highway construction and maintenance tasks

Type of Equipment Working Speed, mph (km/h) Reaction Distance a, ft (m) Braking Distance, ft (m) Distance to be Illuminated in Front and Back of Equipment b,c, ft (m) Slow-moving Equipment Paver Milling Machine 4–5 (6.4–8) 11 (3.4) 5 (1.5) 16 (4.9) Fast-moving Equipment Backhoe Loader Wheel Tractor Scraper Wheel Loader Compactor/Roller Motor Grader 10–15 (16.1–24.2) 33 (10.1) 15–25 (4.6–7.6) 58 (17.7) a Reaction distance = 2.2 x working speed b Distance to be illuminated = reaction distance + braking distance c Minimum illumination level of 10.8 lx (1 fc) at maximum distance TABLE 10 Recommended illuminated distance in the direction of travel for various types of construction equipment provided in the Table 9 should not be less than 10.8 lx (1 fc), the task illumination levels around the equipment should con- form to the categories and minimum levels recommended for various tasks. Assessment of Glare Hazard Glare hazard, both disability and discomfort, is a serious problem on highways. The various sources of glare affecting the work crew and the motorist include: 1. Glare from passing vehicles, 2. Glare from temporary work area lighting, and 3. Glare from lighting on construction equipment. The intensity levels for organic lighting on construction equipment were not found to be high. However, retrofitted equipment lighting installed after manufacture was often high intensity and could cause glare problems. Glare result- ing from stationary light plants is potentially the most severe for motorists and workers. There are several methods which have been suggested to evaluate and quantify glare: 1. Between comfort and discomfort (BCD) illuminance levels, 2-18 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2. Glare control mark, and 3. Visual comfort probability. These methods are useful for fixed or stationary situations. However, it is difficult to specify and achieve such levels con- sidering the dynamics of highway construction work zones. Instead, a more practical approach of controlling glare has been adopted in this study. This approach includes (1) avoid- ing glare to the workers from the headlights of the traveling vehicles and (2) reducing glare from the light plants to the motorists. To avoid glare to the workers from the headlights of the traveling vehicles, several measures can be taken. Glare avoidance screens or barrier walls are usually used as a measure to protect workers from outside glare. Often height of the barrier walls was not thought to be sufficient to com- pletely protect the work zone from vehicle lights. As a result, additional screens, panels, or paddles were mounted on the barrier walls to help separate the lanes and reduce glare. In order to limit the glare from stationary tower light plants to the motorists, appropriate lighting configuration was determined to be a viable solution. In some cases, the motorist may be protected from the work zone lighting by providing screens on top or by mounting lamps below the top edge of the barrier wall. However, in the most general case where light sources are elevated, the glare hazard can

SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-19 be most efficiently controlled by selecting an appropriate configuration and controlling the beam angle. Figure 5 illustrates the relevant geometry between light source and the observer. Beam angle is measured as the angle between the center-line of the beam and vertical and eccentricity are given by angular distance of the light source from the line of sight of the observer. According to one study, the amount of glare decreases or BCD luminance increases as beam angle decreases and eccentricity increases (4). However, for a typical highway work zone situation, maximum eccentricity is limited and cannot exceed the total width of a few lanes. As a result, beam angle is the only controlling factor available for glare control. Beam angle, if reduced substantially, can cause signifi- cant adverse effects on beam spread, area of illumination, and uniformity. A beam angle of not more than 60 degrees for elevated flood lights is most appropriate and also appears to agree with several SHA specifications. The max- imum height of the tower for this beam angle was limited to 9.2 m (30 ft). Line of Sight Observer C. L. Be am Light Source V er tic a l Hor izon tal B E Where, B: Beam angle with vertical E: Eccentricity of observer’s position Figure 5. Effect of beam angle and eccentricity in reducing glare.

2-20 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK CHAPTER 3 FIELD DEMONSTRATION OF ILLUMINATION GUIDELINES INTRODUCTION This study has focused on the subject of lighting construc- tion work zones during nighttime highway construction. The primary objectives have been to develop guidelines that can be used by the practitioner to safely and efficiently design and maintain work zone lighting systems. Candidate guidelines were developed based on the best currently available science and were presented in Chapter 2. However, to evaluate the applicability of these guidelines, the construction job site may be the ultimate test of engineering theory. Trial of the proposed guidelines on an actual construction site was con- sidered to be essential. Consequently, the research team undertook a field demonstration of the guidelines as a part of Phase I of the project. DEMONSTRATION OBJECTIVES The overall objective of this field research was to validate the proposed guidelines. The following specific objectives have been identified: 1. Evaluate the adequacy of the format and user under- standing of the work zone lighting design procedures presented in the guidelines. 2. Evaluate the constructability and feasibility of the lighting configuration and systems suggested by the guidelines. 3. Evaluate the performance effectiveness of the lighting plan suggested by the guidelines. 4. Evaluate the cost of designing and implementing a light- ing plan in accordance with the guidelines. DEMONSTRATION PROCEDURE The investigators obtained agreement from the Florida Department of Transportation (FDOT) and Hubbard Con- struction Corporation, an FDOT contractor, to participate in the field trial. Although FDOT’s current lighting specifica- tion is substantially different from the proposed guidelines, both parties agreed to try to provide lighting on a specific proj- ect according to the proposed guidelines. The research pro- cedure consisted of the following tasks. Task 1. Project Selection and Development of Lighting Design An FDOT project was selected because its work schedule fit within the time limitations available for this research study and because it was expected to involve some work activities in all three illumination levels specified in the guidelines. The proj- ect, titled Resurfacing University Boulevard, located in Jack- sonville, consisted of the asphalt pavement resurfacing of an existing approximately 3.2-km (2-mi) four-lane arterial road. Working with the contractor’s supervisory personnel, the research team developed a lighting design and a lighting plan for the project. This design is included in Appendix for Sec- tion Two: Lighting Design for Demonstration. During the design and planning process, the research team accessed the suitability of the guidelines as a design tool to be used by contractor personnel. Task 2. Implementation of the Design Implementation of the design consisted of the following lighting modifications to the contractor’s equipment. Asphalt Paver—Cedar Rapids 451. Figure 6 provides the detail of the lighting arrangement on the paver. The design modification consisted of adding one 1,000-W metal halide luminaire mounted in the center of the rear side of the paver to provide lighting to the finished pavement area directly behind the paver. The luminaire was mounted with an adjust- able yoke mount and provided with a cutoff baffle. Power was supplied by portable gasoline powered generators mounted on the deck of the paver. Pavement Rollers—Galion and Hyster. Figures 7 and 8 give the details of the lighting arrangements on the pavement rollers, respectively. The design improvement consisted of adding two additional 55-W quartz halogen lamps to the Galion machine and one additional quartz halogen lamp to the Hyster machine. These additional luminaires were mounted on a bracket bar installed on the front of the machine. Power was supplied by the internal DC alternator. Portable Light Tower—Four 1,000-W MH. The portable light tower was modified by adding cutoff shades to each of

SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-21 the four flood lights. These glare control shades were easily attached with spring clips provided with the shades. Task 3. Performance Observations Construction of the project was performed by the contrac- tor with the modified equipment lighting. The research team made observations regarding the following: 1. Actual illumination as compared with the lighting plan and guidelines. 2. Suitability of the lighting in terms of work performance and opinions of the participants. Design Guidelines. Contractor’s supervisory personnel were able to follow the procedures in the guidelines with the assistance of the research team. However, this experience suggests that training would be required in most cases prior to a contractor’s successful use of the design procedure. Existing 400w MH Each side Existing 100w halogen DC Lamp each side Existing Gasoline AC Generator each side Existing 2 – 400w MH Floods each side, 10’-0” above ground Added 100w MH 12” Parabolic Narrow Flood centered 10’-10”above ground Machine width 9’-6” Figure 6. Detail of lighting configuration on asphalt paver. 5’-3” 4’-9” 7’-5” Existing 100 w halogen each side Existing 100w halogen each side Added 2 ea. 100w halogen mounted on bracket 3’-0”spread Figure 7. Detail of lighting configuration on Galion Roller.

Lighting Equipment Availability, Installation, and Cost. All of the additional luminaires added to the project were readily available from retail suppliers. The contractor’s nor- mal equipment maintenance personnel accomplished mount- ing of the luminaires with minimal labor. The total cost of all modifications was approximately $1,628. This is clearly a small cost increase on a project with a total budget exceeding 1 million dollars. Table 11 summa- rizes the additional lighting costs. Lighting and Work Performance. The research team mea- sured actual illumination. The results of the illumination mea- surements are summarized in Figure 9. Target illumination levels were obtained in the design work area in all cases. Uni- formity ratios exceeded the target value in the case of the asphalt paver and with the portable light tower. A summary of the illumination results by work task is provided in Table 12. Work performance was observed to meet or exceed the project quality requirements and the contractor’s production expectations. No significant safety or quality control incidents occurred. It was reported that this achieved performance level is typical for this contractor and cannot necessarily be related to the project’s lighting upgrade. Nevertheless, the majority of the working participants did agree that the improved light- ing made their jobs easier. A summary of the participants’ survey is presented in Table 13. Analysis, Appraisal, Application. The design procedures suggested in the Guidelines for Work Zone Illumination Design were successfully used to design the lighting systems for the demonstration project. Area lighting was not the only design requirement. Each task and each piece of construction 2-22 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK equipment required unique task lighting in addition to the general area lighting. Task 4. Evaluation and Summary The research team evaluated and summarized the results of the demonstration project. Appropriate modifications to the guidelines are suggested. In addition, the following “lessons learned” were obtained from the demonstration project: 1. Each piece of equipment and each task has unique task lighting requirements in addition to general area light- ing requirements. 2. Equipment operators are a good source of information about areas they need to see while performing tasks. 3. Experienced night workers adapt to varying lighting situations and use indicators other than light to perform their tasks, such as sound. 4. The lighting of construction equipment could be very much facilitated if equipment manufactures would pro- vide lighting or at least increase amp capacity. 5. The use of glare control shades on luminaires is an inex- pensive and effective glare counter measure. The three categories of illumination levels appeared to successfully cover the work tasks in the demonstration proj- ect. A listing of the tasks performed under each illumination level category was previously given in Table 10. Pavement rolling was changed from Category II (108 lx, 10 fc) to Category I (54 lx, 5 fc). This change was made during 5’-3” 4’-5” 4’-11” Existing 100 w halogen each side Two existing plus one added 100w halogen mounted on bracket 3’-0” spread Figure 8. Detail of lighting configuration on Hyster Roller.

SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-23 EQUIPMENT LIGHTING ADDITIONS MATERIALS AND LABOR COST Asphalt Paver—Cedar Rapids 451 Added 1 ea. 100 w metal Halide Flood – Ruud No. 4410-D 1 ea. Spare Replacement Luminaire Luminaires Pipe support Wiring Installation Labor $462.00 $3.00 $12.00 $18.00 $495.00 Pavement Roller— Gallion Dresser Added 2 ra. 55 w Qtz Halogen Lamps, CAT 8180 1 ea. Spare Replacement Luminaire Luminaires Bracket Bar Wiring Installation Labor $117.00 $22.00 $10.00 $36.00 $185.00 Pavement Roller— Hyster Added 3 ea. 55 w Qtz Halogen Lamps, CAT 8180 2 ea. Spare Replacement Luminaire Luminaires Bracket Bar Wiring Installation Labor $156.00 $18.00 $10.00 $36.00 $220.00 Portable Light Tower Added 4 ea. Glare Control Shades General Elec. PSON34 Glare Control Shades Installation Labor $728.00 $0.00 $728.00 TABLE 11 Summary of lighting upgrade costs Asphalt Paver 494.6(45.8) Target Illum. 108(10) 101.5(9.4) Actual 154.4(14.3) 45.4(4.3) Uniformity Ratio 4.5 96.1(8.9) 3.3m 34.6(3.2) 1m 2m 3m 4m 5m Pavement Roller – Gallion Dresser 34.6(3.2) Target Illum. 108(10) 57.2(5.3) Actual 60.0(5.6) 81(7.5) Uniformity Ratio 1.1 73.4(6.8) 3.3m 54(5) Illum. at 20m 16.2(1.5) 1m 2m 3m 4m 5m Pavement Roller – Hyster 21.6(2) Target Illum. 108(10) 136.1(12.6) Actual 54.2(5) 41.0(3.8) Uniformity Ratio 2.5 27(2.5) 3.3m 45.4(4.2) Illum. at 20m 10.8(1.0) 1m 2m 3m 4m 5m Portable Light Tower 35.6(3.3) Target Illum. 108(10) 91.8(8.5) Actual 381.9(35.4) 237.6(22) Uniformity Ratio 10.7 302.4(28) 3.3m 1242(115) 1m 4m 8m 16m 20m Figure 9. Illumination of measurement results.

the design process based on consultation with the FDOT field engineer and the contractor’s field supervisors. Additionally, the lighted work area for the roller was set as an area 3.3 m by 6.1 m (11 ft by 20 ft). Both of these changes appear to have worked well. Meeting the suggested maximum uniformity ratio of 10.0 was difficult in some cases. For example, the illumination level directly adjacent to the asphalt paver was 494.6 lx (45.8 fc). This hot spot was the result of focusing the addi- tional 100-W metal halide lamp at an angle of approximately 60 degrees with the vertical to control glare. The actual uni- formity ratio of 14.3 was not detrimental to the performance of the work. Maintaining the 10.8 lx (1 fc) levels at the seeing horizon distances for moving equipment was also successful. This 2-24 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK requirement was obtainable and appeared to match the work requirements. The use of glare control shades on the portable light tower worked well. These devices are easily attached to the lumi- naires with spring clips. Their use significantly reduced glare from the tower lamps. All of the lighting hardware used was readily obtainable. No special or unusual luminaires were used. Costs were min- imal. Neither costs nor availability of equipment were obsta- cles to implementing the proposed illumination guidelines. In summary, the Guidelines for Work Zone Illumination Design provided a simple, straight-forward procedure for designing work zone lighting. However, the guidelines could be enhanced by including a discussion of the need to consider the unique requirements of each task. Category Target Illumination Level Task Measured Illumination (Average) I 54 lx (5 fc) Water movement Sweeping Clean up Pavement rolling 54 – 60.4 lx (5.0 – 5.6 fc) II 108 lx (10 fc) Asphalt Paving Worker activity around paver Racking, shoveling asphalt 154.4 lx (14.3 fc) III 216 lx (20 fc) Maintenance of equipment Set up of asphalt distributor 382.3 lx (35.4 fc) TABLE 12 Summary of illumination measurements by work task How does the lighting on this project compare with last project you worked on? Very Much Better 2 Somewhat Better 6 About the Same 2 Not as Good 1 How would you rate the lighting on this project with regard to your ability to do your job? Very Good 1 Good 3 Just O.K. 6 Poor 1 Indicate whether or not this project should have more or less light in the work area. Much More A Little More 4 About the Same 7 Less Light Indicate your job classification. Supervisor 1 Engineer/ Inspector 1 Equipment Operator 3 Workman 6 TABLE 13 Summary of participants’ survey

SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-25 CHAPTER 4 RECOMMENDED ILLUMINATION GUIDELINES INTRODUCTION This chapter presents a summary of the findings and rec- ommended guidelines for illumination of nighttime highway work resulting from this study. The content of the guidelines includes recommended minimum illumination levels for dif- ferent nighttime highway work tasks, glare control require- ments, and implementation considerations. These guidelines may be used by specifying agencies such as SHAs when developing standards for nighttime highway work and may provide guidance for professionals in the design and imple- mentation of work zone lighting. Minimum Illumination Requirements Suggested minimum illumination requirements are pre- sented in Table 14. Typical night work activities are assigned to one of three lighting requirement categories: Category I Minimum illumination of 54 lx Category II Minimum illumination of 108 lx Category III Minimum illumination of 216 lx Table 14 also provides guidance with regard to the minimum illuminated area for different stationary and moving tasks. Glare Control Requirements Suggested requirements for glare control and avoidance are presented in Table 15. Of the recommendations, proper aiming and the use of glare control shading hardware appear to be the most effective countermeasures. Related Implementation Issues Training Field reviews at numerous projects in many states suggest that the technical aspects of work area lighting are relatively new to both SHA and contractor field personnel. Clearly there is a need for basic training with regard to properly con- figuring and maintaining the lighting of a nighttime highway work area. Suggested subject areas are • Review of specified lighting standards, • Minimum levels of illumination, • Glare control requirements, • Lighting hardware options and characteristics, and • Proper equipment mounting of luminaires. More advance training may be appropriate for designers of work area lighting plans and for those persons responsible for reviewing lighting plans. Adjusting Lighting Requirements to Specific Tasks The recommended minimum illumination requirements are general in nature. A review of the specific task should be performed to determine task-specific lighting requirements. This examination of the work process and detail may indicate additional specific lighting needs related to the performance of the task. This review of the task seeing requirements should include experienced equipment operators and workers. For example, the operator of a pavement roller normally is look- ing at the pavement surface in advance of the machine; how- ever, if the pavement is being placed against a concrete curb, the operator must also be able to see the edge of the roller wheel. Input from the field work force is an important factor in successful lighting design and implementation. Avoid Omitting Ancillary Activities Normally, attention is focused on the primary construction or maintenance activities. Lighting plans and configurations are established to accommodate these key production activi- ties, such as the placement and compaction of asphalt pave- ment. Care must be taken to ensure that other ancillary activ- ities also have adequate lighting. For example, inspection of asphalt pavement typically occurs at a considerable distance from the location of the paver and the following rollers. Pro- visions must be made so that the quality control and accep- tance activities are also properly lighted. Another example occurs in the construction of portland cement concrete pavements. Management attention generally focuses on the paving operation receiving adequate lighting. However, several hours after the paving operation has passed,

Average Maintained Illumination Description of Construction and Maintenance Task Category Target Level lux (fc) Recommended Illumination Areas for Typical Highway Construction Equipment Excavation – Regular, Lateral Ditch, Channel I 54 (5) Embankment, Fill and Compaction I 54 (5) Barrier wall, Traffic Separators II 108 (10) Milling, Removal of Pavement II 108 (10) Provide target illumination over task working area. This is the effective working width of the machine by approximately 5 meters. Asphalt Paving and Resurfacing II 108 (10) Minimum distance from machine to Concrete Pavement II 108 (10) Asphalt Pavement Rolling I 54 (5) Subgrade, Stabilization, and Construction I 54 (5) Base Course Grading and Shaping II 108 (10) Surface Treatment II 108 (10) Base Course Rolling I 54 (5) Waterproofing and Sealing II 108 (10) Sidewalk Construction II 108 (10) Sweeping and Cleaning I 54 (5) Slow Moving Equipment: Paver Milling Machine 5 meters Guard Rails and Fencing II 108 (10) Striping and Pavement Marking II 108 (10) Landscaping, Sod and Seeding I 54 (5) Highway Signs II 108 (10) Traffic Signals III 216 (20) Highway Lighting Systems III 216 (20) Bridge Decks II 108 (10) Fast Moving Equipment: Backhoe Loader Wheel Loader Scraper Roller Motor Grader 20 meters Drainage Structures and Drainage Piping II 108 (10) Other Concrete Structures II 108 (10) Maintenance of Embankments I 54 (5) Reworking Shoulders I 54 (5) Repair of Concrete Pavement II 108 (10) Crack Filling III 216 (210) Pot Hole Filling II 108 (10) Repair of Guardrails and Fencing II 108 (10) Other Equipment: Maximum uniformity ratio of 10:1 in the work area. Minimum of average maintained illumination of 54 lx (5 fc) for all work areas. Implement Glare Control Measures. (See Table 15 for Glare Control Check List.) TABLE 14 Recommended target illumination levels and lighting guidelines Beam Spread Select vertical and horizontal beam spreads to minimize light spillage. Consider using cutoff luminaires. Mounting Height Coordinate minimum mounting height with source lumens (see Figure A-2). Location Luminaire beam axis crosses normal lines of sight between 45° and 90°. Aiming Angle between main beam axis and nadir less than 60° (see Figure 5). Intensity at angles greater than 72° from the vertical less than 20,000 candela. Supplemental Hardware Visors Louvers Shields Screens Barriers TABLE 15 Glare control check list

joints must be cut in the pavement; the saw cutting crew may be left without adequate lighting. REFERENCES 1. Standard Specifications for Road and Bridge Construction, Florida Dept. of Transportation (1991). SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-27 2. IES Lighting Handbook. Illuminating Engineering Society of North America, New York, NY (1993). 3. SAE Handbook. “On-Highway Vehicles and Off-Highway Machinery,” Vol. 4, Society of Automotive Engineers, Warren- dale, PA (1991). 4. Hinze, J. and Carlisle, D., “Variables Impacted by Nighttime Construction Projects.” Final Report TNW 90-07, Transporta- tion Northwest, University of Washington, Seattle, WA (Feb. 1990).

2-28 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK APPENDIX FOR SECTION TWO LIGHTING DESIGN FOR DEMONSTRATION ROLLERS Based on the design criteria, rollers were classified as a Category II with an average illuminance of 108 lx (10 fc), a uniformity ratio of 10
1, and an illumination area of 17.7 m by 3.3 m (58′ × 11′) at each end of the equipment. After meet- ing with the contractor and equipment operators, it was deter- mined that the work zone could be reduced to 6 m (20′) and that 54 lx (5 fc) would be sufficient illumination. This effec- tively reclassifies the equipment as Category I. Since there is limited mounting space to support a tower, 55-W incandes- cent, sealed beam lamps will be mounted on the frame for this equipment. Given an area of 19.8 m2 (220 sf) and a required illumina- tion level of 54 lx (5 fc), the necessary wattage can be found as follows: Recommended watts/m2: 12 (Figure A-1) The recommended headlamp is a Caterpillar composite halogen lamp assembly. A high beam lamp is selected for extended throw. Four will be required in each direction (front and rear). Project results for the roller indicate the validity of the sim- plified design procedure. The Gallon Dresser roller equipped with four lamps achieved the desired 54 lx (5 fc) with an excellent uniformity ratio. As a result of the demonstration, the lighting criteria for roller operations were revised to be a Category I require- ment at 54 lux (5fc). Because of the rolling patterns used by the roller operators, the seeing task is performed adequately at Category I illumination level. Inspection and quality con- trol activities are likely to require additional task-specific illumination. PAVER Based on the design criteria, pavers are classified as a Cat- egory II with an average illuminance of 108 lx (10 fc), a uni- formity ratio of 10
1, and an illumination area of 4.9 m by Number of lamps: watts55 watts / lamp 4.3 lamps (use 4) 238 = Total wattage: w m 19.8m watts2 12 238× = 3.3 m (16′ × 11″) at the back end of the equipment. After meeting with the contractor and equipment operators, it was determined that in addition to the work zone lighting, it would be beneficial to provide task lighting for moving parts such as the screed. Since this lighting is highly directional, it will not be con- sidered in the determination of the work zone lighting requirements. The required area of illumination was extended by 1.2 m due to the mounting position of the light on the paver. For this application, a post mounted metal halide fix- ture is recommended. Given an area of 19.8 m2 (176 sf) and a required illumi- nation level of 108 lx (10 fc), the necessary wattage can be found as follows: Recommended watts/m2: 4 (Figure A-1) From manufacturers’ literature (RUUD Lighting), a nar- row parabolic luminaire is selected to minimize light spillage to the sides of the work zone. A 100-W metal halide lamp is selected as the next available size (50, 70, 100, 175). From Figure A-2, it is then determined that there are no constraints on the mounting height for this wattage. The light will be mounted at 3.3 m (11′). Since the supplemental task lighting installed by the con- tractor is directed on the screed, it does not play a signifi- cant role in the work zone calculation. Comparison of the actual results with those simulated using AGI lighting soft- ware is again favorable. The required average work zone illumination is achieved with uniformity ratios within accept- able limits. PORTABLE LIGHT TOWER Commercially available portable light towers are usually equipped with four 1000-W metal halide lamps and have a maximum extended height of 9 m (30′). Based on the rela- tionship between mounting height and source lumens, it is evi- dent that this equipment will be a tremendous source of glare since the minimum acceptance mounting height for a 1,000-W metal halide is approximately 14 m (46′). This phase of the demonstration determines the effectiveness of glare control devices while maintaining adequate illumination levels. Total wattage: 4w m m 79 watts2 2× =19 8.

SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK 2-29 Figure A-1. Recommended watts/m2 for different illumination levels. Figure A-2. Recommended relationship between mounting height and source lumens.

Assuming the work zone to be illuminated has an area of 56 m2 (600 sf) and a required illumination level of 108 lx (10 fc) the necessary wattage can be found as follows: Recommended watts/m2: 4 (Figure A-1) Total wattage: 4w m m 2 watts2 2× =56 38 2-30 SECTION TWO: ILLUMINATION GUIDELINES FOR NIGHTTIME HIGHWAY WORK Although only 224 W are necessary, the equipment in common use operates at 4,000 W. For the demonstration, a mounting height of 3.7 m (12′) was selected due to equip- ment constraints. AGI software molding of the illumination levels indi- cated illumination levels far exceeding required results. Based on a simple visual analysis, the reduction in glare was significant.