How to Measure and Communicate the Value of Access Management (2023)

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21   Medians physically separate opposing traffic, limit access and conflicts, and provide better pedestrian refuge than roadways that are undivided or have TWLTLs. Median design involves adequate provision for left turns and U-turns to accommodate turning maneuvers and avoid con- centrating too many of these movements at signalized intersections. The value of nontraversable medians relates primarily to safety, as well as to livability/aesthetics. Medians have been used to beautify roadway corridors with landscaping features. Medians with landscaping and pedestrian provisions also fit into roadway cross-section designs desirable for context zones where more pedestrian use is encouraged. Despite their many benefits, the decision to replace continuous TWLTLs with a raised median or to install a raised median on an undivided roadway is often highly controversial. Concerns may arise with regard to impacts on business activity, circuity of access, impacts on neighborhood traffic circulation, access for delivery vehicles, and the safety of U-turns. The Median Treatments section of the AMC Toolkit offers a variety of tools, a guide to research, and messaging strategies to communicate the value of medians, while also addressing public concerns. This section of the report provides sample talking points and additional details on how to estimate the anticipated reduction in crashes and improvements to mobility that may be expected when a median is installed and the relative cost savings to society. An example application of the tools is included in Chapter 8: Case Studies (Converting a TWLTL to a Raised Median). Talking Points Talking points regarding the value of medians and well-designed median openings that can be supported with the simple tools and resources in the toolkit include: • Nontraversable medians improve safety by limiting left turns to well-planned, designated locations. – Left turns increase major conflicts between vehicles and with other roadway users. More than two-thirds of all access-related collisions involve left-turning vehicles (Williams et al., 2014). Left turns also represent the highest injury and fatality crashes on at-grade arterials. – Left turns can increase delay and complicate signal timing. – Pedestrian safety is improved both by reducing left-turn conflicts and by providing a crossing refuge. • When median openings are too closely spaced, they cause a variety of safety and operational problems. • Median openings near signalized intersections are a special safety issue. Placing a full median opening opposite an access point near a signalized intersection creates numerous conflicts between turning and through vehicles and must therefore be avoided. C H A P T E R 3 Medians and Median Openings

22 How to Measure and Communicate the Value of Access Management • Too many driveways near a median opening with heavy turning volumes increase the fre- quency of vehicle conflicts and the potential for crashes. • Directional median openings offer opportunities for left-in, left-out, or U-turn movements while reducing midblock and severe crashes often associated with full openings that allow all movements. • Raised medians provide space for landscaping, art, and other aesthetic treatments that can improve the livability and character of a major roadway corridor. • By enhancing the appearance of a transportation corridor or by improving the flow of traffic through the area, median treatments may also increase the value of property. Measuring Safety Performance The MedianType.xlsx spreadsheet tool allows the user to estimate the impacts of median type on safety performance. Using methods provided in the HSM (AASHTO, 2010) the tool separately evaluates the median and the driveway influence area and separates single-vehicle (SV) crashes from multiple-vehicle (MV) crashes. The MedianType.xlsx tool estimates the number of driveway and non-driveway-related crashes that may be expected on four-lane urban/suburban arterials based on: • Median type (undivided, TWLTL, median). • Number and type of driveways. Inputs include facility type, annual average daily traffic (AADT), segment length, and types of driveways (major or minor commercial, industrial, residential). Begin by selecting the type of facility: • 4U: four-lane arterial undivided. • 5T: four-lane arterial with continuous TWLTL. • 4D: four-lane arterial with raised median. Next, select from the menu the type and number of driveway access points present on the corridor based on land use type and number of parking spaces. The relative number of parking spaces may be identified using Google. Outputs include total segment crashes per year for driveway (Dwy) and non-driveway crashes, as well as fatal plus injury crashes. Non-driveway crash numbers are reported for single vehicle, multiple vehicles, and both. Examples of tool outputs are illustrated in the Traffic Safety Fact Sheet titled “Two-Way Left- Turn Lane (TWLTL) and Raised Median on an Urban/Suburban Roadway” that is included with the AMC Toolkit. For example, the outputs demonstrate that converting a TWLTL to a raised median can be expected to reduce yearly crashes by about 27% for daily traffic volumes of approxi- mately 20,000 to 25,000 vehicles per day (vpd). The MedianOpeningNearSignalizedIntersection.xlsx spreadsheet tool allows the user to estimate the impacts of median opening type on safety performance. Using quantitative values identified in NCHRP Research Report 929 (Dixon et al., 2020) and analytical techniques presented in the HSM (AASHTO, 2010), the tool estimates the number of crashes that may be expected due to median openings on urban/suburban arterials near a signalized intersection based on: • Median opening type. • Number of arterial through lanes. Inputs include median opening type, AADT, and number of through lanes in both directions. Begin by selecting the median opening type: • No opening. • Opening with one turn bay. • Opening with two turn bays. Next, from the menu select the number of arterial through lanes in both directions (four or six lanes). Outputs are total number of crashes.

Medians and Median Openings 23   Examples of tool outputs are illustrated in the Traffic Safety Fact Sheet titled “Median Opening Near a Signalized Intersection” that is included with the AMC Toolkit. For example, tool outputs indicate that a median opening with one turn bay near a signalized intersection on a four-lane roadway with an AADT of 22,000 vehicles per day can be predicted to result in 3.23 crashes and the same scenario for two turn bays can result in 4.82 crashes, increasing the number of predicted crashes by 49%. Measuring Economic Value The primary economic value of medians relates to the value of cost savings due to crash reduc- tion. The cost saving of medians, and other access management techniques, related to safety can be calculated by applying monetized values referenced in Benefit-Cost Analysis Guidance for Discretionary Grant Programs (U.S. DOT, 2020). This information may be used to help quantify the safety benefits, in terms of dollar savings, of access management techniques, as shown in Table 1. This method can be used with any access management technique that results in a change in the number of crashes. Access management techniques with a safety benefit or disbenefit gener- ally result in a change to the number of fatalities and injuries on the roadway; however, adding a median also results in changes to the number of property damage only crashes. Inputs for calculating the safety cost savings rely on the change in crashes calculated in the safety tool. The input for the economic tool is the calculated change in crashes. The change in crashes can be calculated by injury type or unknown if injured, depending on the available data. Outputs are the monetized value associated with the calculated change in crashes. The following calcula- tions determine the monetized value of the change to safety. Total Crashes no treatment Total Crashes with treatment Monetized Value of Crashes Safety Benefit { }( ) ( ) ( ) − × = $ For example, if a median addition leads to a calculated change in crashes (unknown if injured) of 3.43, the monetized value of the change is $472,000 (results are rounded for clarity). { } × =3.43 $137,600 $472,000 In terms of property damage, the calculated change to crashes is −0.29, which leads to a mon- etized value of −$1,305. In this example, there is an increase in property damage only crashes resulting in a cost, or a disbenefit. Nonetheless, there is an overall significantly greater benefit when considering total crashes. KABCO Level Monetized Value ($2018 inflated to $2020) O–No Injury $3,300 C–Possible Injury $66,380 B–Nonincapacitating $129,800 A–Incapacitating $476,900 K–Killed $9,973,000 U–Injured (Severity Unknown) $181,100 Accident Reported (Unknown If Injured) $137,600 Property Damage Only (PDO) $4,500 Table 1. Monetized value of crashes (2020).

24 How to Measure and Communicate the Value of Access Management If crash type is known, the calculation depends on the severity of the crash. The monetized value of the crash differs, depending on severity. For example, the calculated change in crashes for a nonincapacitating crash would be: { } × =0.23 $128,900 $29,900 For an incapacitating crash, the calculation would be: { } × =0.23 $476,900 $109,700 Assessing Business Activity A clear indication of the compatibility of access management and nontraversable medians and retail business is the number of miles and locations throughout the nation where retail businesses thrive along median-divided, access-managed highways. While the effects of access management on retail sales are understandably a concern, access management can provide a critical business benefit by expanding the potential customer base. Any effects on retail activity must be balanced with the economic impacts and suffering caused by the significantly higher crash rates that occur when a nontraversable median is not in place. Business owners often react negatively to medians due to concerns that a loss of left-turn ingress or egress may deter customers and reduce sales activity. The value of median projects to corridor businesses may be quantified on a corridor-specific basis using surveys, sales tax data, or retail sales numbers. Another way to address business concerns is by communicating the results of past studies, many of which show that access management does not adversely affect business activity and may in fact improve business. Some examples of studies to date include the following: • In Utah, a study of the impact of raised medians found that corridors where raised medians were constructed saw an increase in retail sales and no evidence of negative impacts due to these projects (Riffkin et al., 2013). • Weisbrod and Neuwirth (1998) assessed the economic impact of restricting left turns at nine case study sites. Results showed that type of business was important when considering impact; those negatively affected were gas stations, nondurable goods retailers, and service businesses, but grocery stores and restaurants saw increased sales and decreased business failures. • NCDOT conducted a study using a perception-based survey, with comparison sites, and busi- ness revenues to create a pseudo-before and after study. Business owners in the study were more favorable to access management after the construction of a median than before, and business revenues showed no direct evidence of negative economic consequences due to the installation of access management treatments on the corridor (Cunningham et al., 2010). • A Kansas DOT study evaluated 15 businesses that had filed inverse condemnation lawsuits against KDOT on access-related issues. In all but one case, the claimant was still in possession of the property and operating the business, the property was being used for the same purpose by a different operator, or the use of the property had been upgraded (Kansas DOT, 2000). Assessing Property Values Property values tend to increase rapidly during commercial development but can decline if the character and efficiency of that corridor have been damaged in the process. It follows, therefore, that median projects, particularly those that are accompanied by aesthetic improvements, such as landscaping, can positively impact property values. Medians may also incrementally enhance

Medians and Median Openings 25   property values where they can be shown to reduce delay and increase the flow of traffic through an area. To date, studies of corridors where medians have been instituted have found either no change or an increase in property values following the project. The value of medians to property values may be quantified using data on assessed valuation. Property values tend to be cyclical, with a life cycle in four stages: growth, stabilization, decline, and revitalization. Improper management of access connections and intersection controls causes the investment in the growth cycle to be compromised, the stabilization phase to be shortened, and the decline phase to deepen. This hastens the need for the revitalization phase and shortens not only the economic life of the property improvements but also the economic life of transportation corridors. It is proven that retrofit projects, particularly those that are accompanied by aesthetic improvements such as landscaping, can positively impact property values and preserve economic life of corridors. Medians also serve to enhance property values where increased traffic volumes are safely accommodated by the retrofits. To date, studies of corridors where medians have been instituted have found either no change or an increase in property values following the project. The value of medians to property values may be quantified using straightforward computation of before and after traffic volumes multiplied by the appropriate constant. A few examples of such studies to date include: • A study in Florida demonstrated that median retrofit projects did not impact property values in 70% of businesses in their sample, and 13% experienced an increase in value (Ivey, Harris & Walls, Inc., 1995). • A Minnesota study of an arterial with major access management improvements found that the location and the local economy were the primary determinants of property values (Plazak and Preston, 2006). • A Texas study found that property values on access-managed corridors either increased or remained unchanged (Eisele and Frawley, 1999). • A study in Kansas demonstrated that access connections are not significant to sale price of commercial property; however, traffic volume is significant (Huffman and Longhofer, 2016). Measuring Mobility Benefits Installing a nontraversable median on an undivided roadway or a roadway with a TWLTL may be expected to result in a reduction in delay to through traffic, due to the reduction in the number of conflict points and the locations where left turns may be made. When a nontraversable median is installed on an undivided roadway and left-turn lanes are provided at median open- ings, through traffic will experience less delay than before, because vehicles stopped to make a left turn will no longer block through vehicles [Highway Capacity Manual, 6th ed. (HCM6), 2016]. The installation of a nontraversable median may have a similar effect on buses as for motor vehicles. If a median prohibits a needed bus turning movement, a median can be designed with a bus-only turn lane to mitigate a potential negative impact. Installation of a nontraversable median can also improve pedestrian crossings by allowing design of an adequate refuge in the middle of the roadway at pedestrian crossings and for two-stage pedestrian crossings. No simple tool can be constructed to assess the mobility implications of a raised median versus TWLTL or undivided roadway scenario. Methods for measuring the value of medians with regard to mobility include: • Statistics from previous research or localized studies on efficiency and time savings. • HCM6 (2016), Chapter 18 (Urban Street Segments), Section 3 (Motorized Vehicle Methodology): Estimates the change in motor vehicle free-flow speed resulting from converting an undivided roadway or a nonrestrictive median to a nontraversable median.

26 How to Measure and Communicate the Value of Access Management • HCM6 (2016), Chapter 18 (Urban Street Segments), Section 6 (Transit Methodology): Esti- mates the change in average bus speeds and bus LOS resulting from improvements in midblock running speed due to the installation of a nontraversable median. • HCM6 (2016), Chapter 18 (Urban Street Segments), Sections 4 (Pedestrian Methodology) and 5 (Bicycle Methodology): Estimate the effect on pedestrian and bicycle LOS of the change in motorized vehicle speeds related to converting an undivided roadway or a nonrestrictive median to a nontraversable median. These changes are small and may not be meaningful for communicating value. • NCHRP Web-Only Document 256: Assessing Interactions Between Access Management Treat- ments and Multimodal Users (Butorac et al., 2018b): Estimates the changes in bicycle speed from the conversion of a roadway with a TWLTL to a nontraversable median, which again are small and may not be meaningful for communicating value. • Traffic simulation models (e.g., VISSIM, TransModeler, Cube Voyager, etc.). The economic value of mobility as it relates to changes in travel time due to access management techniques is discussed in Chapter 5: Signal Spacing. The Safety and Mobility Economic Value.xlsx tool may be used to measure the costs savings from reduced travel time that are attributable to any access management technique. It is discussed in Chapter 5 as signal spacing has the greatest and most measurable benefit to travel time of any access management technique.