Speed Reduction Techniques for Rural High-to-Low Speed Transitions (2011)

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50 CHAPTER THREE SURVEY RESULTS The survey examined the following issues and questions: • Standard approaches to treating high-to-low speed transitions • Enhanced or innovative treatments for high-to-low speed transitions • Case studies. The following sections present the survey results orga- nized into these three areas. SURVEY RESPONSES Standard Approaches Each jurisdiction was asked whether they had a standard approach to treating rural high-to-low speed transitions in both new construction, and retrofit situations. The results show that less than half of the state/provincial respondents have a standard approach to treating rural high-to-low speed transitions, and the majority of the counties do not have a standard approach (see Table 34). TABLE 34 FREQUENCY OF AGENCIES THAT HAVE STANDARD APPROACHES FOR TREATING HIGH-TO-LOW SPEED TRANSITIONS Response New Construction Retrofit Number of Responses Percentage Number of Responses Percentage State/Province No 19 56 22 61 Yes 15 44 14 39 Blank 4 2 County No 18 67 16 62 Yes 9 33 10 38 Blank 1 2 All No 37 61 38 61 Yes 24 39 24 39 Blank 5 4 SURVEY PROCEDURES The 42-question survey was designed to focus on state DOTs and their practices and principles as they relate to speed tran- sition zones on the approaches to rural settlements. Appen- dix A contains the questionnaire. The survey was prepared as an online survey hosted on the TRB website, but was also available in hardcopy or as a MS-Word™ template. The survey questionnaire was trans- mitted to members of the AASHTO Standing Committee on Traffic Engineering in late March 2009. This recipient list included all state DOTs. The online survey was also made available to members of the National Association of County Engineers, and was circulated to traffic engineering personnel in the 10 provinces and 3 territories of Canada through the Transportation Association of Canada. Potential respondents were given 2 weeks to respond. After the initial circulation of the survey, and 2 days before the deadline for responses, a reminder was sent to jurisdictions that had not responded to the first contact. Subsequent to the deadline for responses, telephone contact was made with all nonrespond- ing jurisdictions in an effort to obtain a survey response. Therefore, although participants were initially given 2 weeks to respond, deadline extensions were permitted to increase the response rate. The responses are summarized by the number of and/or percentage of respondents that selected the different answers for each question. The percentages were calculated as the number of answers to each question divided by the number of responses for that question (i.e., the percentages for differ- ent questions may be based on a different number of respon- dents). Also, several questions permitted multiple responses, in which case the sum of the percentages in the question may be more than 100%. Sixty-six responses were received from 36 states, 2 prov- inces, and 28 counties. The response rate for U.S. state DOTs was 72%. The reader is cautioned that the responses from the county government agencies were mainly from agen- cies in California and Iowa, and therefore are not necessar- ily representative of the national experience. As a result, the county-level results are provided as a number of responses, but not as a percentage. Appendix B contains the tabulated survey results.

51 REDUCE SPEED XX mph YY feet • We use advance speed reduction signing unless the situation is such we need to further address safety con- cerns. We generally use “reduced speed ahead” warn- ing signs to warn the driver of the speed reduction. • Utilization of W3-5 or W3-5a signs in accordance with the state MUTCD • Reduce speed limits in increments (50 to 35 and then 35 to 25). • We place signs alerting traffic to the reduced speed and the community. This is typically done with cooperation from the community. “Reduced speed ahead” signs are placed per MUTCD. The speed limit is generally set and posted by the city. We post “Resume Speed” sign as you leave the city and the speed limit returns to state code prescribed speed. We post city name at corpora- tion line with their speed limit in white on green des- tination sign. • Transition speed zones are posted. • “Reduced Speed Ahead” sign followed by a new posted speed limit sign. For respondents with a standard approach to treating high- to-low speed transition areas in retrofit situations, the meth- ods used are the same as those used in new construction. Next, respondents were asked about engineering and infra- structure measures that they considered inappropriate to imple- ment at rural high-to-low speed transitions (see Table 35). The responses are sorted from highest to lowest for the state/province responses, and reveal the following trends: • More than 70% of state/provincial respondents agree that speed humps, raised intersections or speed tables, speed cushions or road studs, removal of all pavement markings, and removal of most traffic signs are inap- propriate measures for speed transition zones. • Less than 20% of state/provincial respondents believe that roundabouts, central islands/raised medians, cen- terline or shoulder rumble strips, speed sensitive sig- nals, marked no-passing zones, amber flashing beacons, speed trailers/radar message boards, variable message signs other than speed trailers, transverse pavement markings, chevrons, or dragon’s teeth, enhanced speed limit signs and/or markings, added standard warn- ing signs, transitional/stepped down speed limits, gateway/entrance features, introduction/alteration of street lighting, or landscaping changes are inappropri- ate measures for speed transition zones. This suggests general agreement among the respondents that the pre- viously noted measures are viable (although not neces- sarily effective) speed reduction techniques. In jurisdictions with a standard approach in new construc- tion areas, the majority of respondents rely on traffic control devices as the primary means of communicating and achiev- ing the speed reduction. Geometric changes at the transition were rarely mentioned and were almost always articulated as transitioning from a rural to an urban cross section. One jurisdiction indicated that the roadway geometry in the speed transition area may be altered by “channelization through marking patterned islands” and roundabouts. Simi- larly, three respondents offered the following road surface treatments as part of their standard approach: • Rumble strips • No road surface treatment unless there is an accident history • Occasional use of raised buttons at points of concern to alert drivers. Off-road features were not part of the standard approach to transition zones for any of the respondents, although one respondent indicated that the local municipality may elect to erect a “city identification structure” at major road entrances. This last comment suggests that many upper-tier road agencies may not consider off-road features in speed transition zones as part of their responsibility, but may not be opposed to permit- ting the local municipality from providing such features. The traffic control devices used to communicate the speed transition in new construction are generally SPEED REDUCED AHEAD signs (W3-5 and W3-5a) as described in the MUTCD, followed by a SPEED LIMIT sign (R2-1) that shows the lower speed limit. Some respondents spe- cifically mentioned that they use progressively lower (i.e., stepped-down) speed limits if the speed reduction is more than 10 mph (16 km/h). Specific comments on standard traf- fic control devices included the following: • Use SPEED REDUCED AHEAD signs (W3-5a) and post new speed according to state DOT policies, guides, and procedures. The usual practice is to drop speeds in 10 mph (16 km/h) increments at transitions. • Standard signing in accordance with MUTCD • W3-5 followed by upsized R2-1 (30x36). Speed reduc- tion greater than 10 mph will typically have 2/10 mile transition zones (i.e., 50-40-35-40-50). Will include a second W3-5 if the second reduction is 10 mph but optional for a 5 mph speed reduction. We would still provide upsized lead speed limit sign for the second speed drop. • Standard speed reduction signing and marking tech- niques; accentuated markings; and hazard identifica- tion beacons • Speed zones are established to be a transition zone between the high and low. Each speed zone has Reduced Speed Ahead Warning signs (W3-5). • We use a black and white sign that says:

52 TABLE 35 MEASURES THAT SHOULD NOT BE USED IN TRANSITION ZONES State/Province Responses (N = 38) County Responses (N = 28) Number of Responses Percentage Number of Responses Percentage Geometric Design Chicanes or increasing road curvature 19 50 15 54 Bulb-outs, neckdowns, chokers, road narrowings 10 26 13 46 Central islands/raised medians 7 18 12 43 Traffic circle 18 47 12 43 Roundabout 6 16 3 11 Road diet, reduction in the number of through lanes 9 24 11 39 Adding bicycle lanes 16 42 7 25 Adding sidewalks or pedestrian paths 13 34 7 25 None of the above 7 18 3 11 Other 1 3 1 4 Surface Treatments Speed humps 32 84 21 75 Raised intersections or speed tables 27 71 15 54 Speed cushions or road studs 27 71 15 54 Pedestrians crosswalks 24 63 13 46 Transverse rumble strips 8 21 3 11 Centerline or shoulder rumble strips 7 18 4 14 Colored or textured pavement 10 26 3 11 None of the above 1 3 2 7 Other 1 3 0 0 Traffic Control Devices Enhanced speed limit signs and/or markings 1 3 0 0 Add standard warning signs 0 0 0 0 Unique (non-MUTCD) traffic control signs 24 63 14 50 All-way stop control 26 38 13 46 Amber flashing beacons 4 11 3 11 Speed sensitive signals 6 16 5 18 Village information signs 9 24 5 18 Speed cameras 15 39 10 36 Speed trailers/radar message boards 5 13 2 7 Variable message signs other than speed trailers 6 16 4 14 Marked no-passing zones 6 16 4 14 Transverse pavement markings, chevrons, or dragon’s teeth 6 16 5 18 Removal of all pavement markings 29 76 22 79 Removal of most traffic signs 29 76 21 75 Transitional/stepped-down speed limit 1 3 0 0 None of the above 1 3 2 7 Other 2 0 0 Roadside Features Gateway/entrance features 6 16 7 25 Landscaping changes 3 8 0 0 Street furniture 9 24 9 32 Introduce/alter street lighting 5 13 2 7 None of the above 14 37 13 46 Other 0 0 0 0

53 Enhanced Measures Recognizing that each transition may require an individu- alized treatment, respondents were asked about their expe- riences with engineering measures that are more than that required by their standard approach (if they have one). These enhanced measures are generally considered when the con- ditions shown in Figure 37 are present. FIGURE 37 Conditions that may prompt more than standard treatment of the transition zone. From a state/provincial perspective, the most frequently mentioned conditions that would prompt consideration of enhanced speed transition measures are a poor crash record (84%), followed by public opinion, access density, and a • The remaining engineering measures received mixed reactions from the respondents, perhaps indicating that there is no clear consensus of the usefulness of these measures in speed transition zones. With respect to documentation on agency practices regarding speed transition zones, one state (Arizona) pro- vided its traffic engineering policy on speed limit signing, and Vermont referenced its Traffic Calming Study and Approval Process for State Highways. The Arizona policy provides slightly more detail than the federal MUTCD in the application of advance signing. The Vermont document was created in 2003 to provide information about the process for planning, evaluating, and implementing traffic calming projects on state highways in Vermont. A particularly insightful diagram from the Vermont doc- ument is reproduced in Figure 36. There are several points to note concerning this figure: • There are three distinct zones denoted rural/open, transition, and village, all of which must be considered for a successful speed transition. • The prototype uses a stepped-down speed limit of 40 to 45 mph to buffer the transition from the 50 mph rural area to the 25 to 35 mph in the village. • The transition zone terminates at an entry/gateway, which may include median islands, neckdowns, roundabouts, village identification signs, and speed limit signs. FIGURE 36 Standard approach to transition zones for Vermont [Source: Vermont Agency of Transportation (2003)].

54 significant drop in the posted speed limit (68% to 70%). It is interesting to note that at the county level, public opinion is the most frequently mentioned factor that is considered in implementing enhanced engineering measures for speed transition zones, followed by average daily traffic. When a speed drop is mentioned, the magnitude of the minimum speed drop ranges from 10 mph (16 km/h) to greater than 30 mph (50 km/h) for state/province respon- dents, and 5 mph to 30 mph (8 km/h to 50 km/h) for county respondents (see Table 36). The most frequently mentioned minimum speed drop to consider enhanced treatments for speed transitions is 15 or 20 mph (24 or 32 km/h). TABLE 36 MINIMUM SPEED REDUCTION TO WARRANT ENHANCED MEASURES Minimum Speed Drop, mph (km/h) State/Province County 5 (8) 0 1 10 (16) 4 4 15 (24) 8 4 20 (32) 8 1 25 (40) 0 0 30 (50) 1 1 35 (60) 1 0 The other factor that is considered by one county is the presence of agricultural equipment on the road. The size of the settlement is not a factor considered by many of the state/province (N = 2) or county (N = 4) respon- dents in deciding on enhanced speed transition measures. However, agencies that mentioned the size of the settle- ment as a factor cited population of the settlement, length of development fronting on the street, and presence of certain amenities in roughly equal amounts as the specific indicator of settlement size. The respondents have tried several different engineering treatments in addition to their standard practices to transi- tion from high-to-low speeds. With respect to state and provincial respondents, almost half (48%) of the enhanced measures were traffic control devices, followed by geomet- ric design measures (22%), surface treatments (18%), and finally roadside features (12%) (see Figure 38). The county respondents yielded a similar profile of responses. Perhaps more telling is that between 40% and 50% of state/provincial and county respondents have never tried any geometric design, surface treatment, or roadside measures outside of what might be considered the standard approach. Although practitioners generally recognize that traffic sign- ing alone is an ineffective method of managing speed, the respondents have been reluctant to experiment with more aggressive and physical measures. State and Provincial Respondents County Respondents FIGURE 38 Categories of measures tried in transition zones. There were a total of 17 case studies reported by respon- dents (10 from state DOTs and 7 from county engineers). The Vermont Agency of Transportation case study referred to its experimentation and evaluation of dynamic striping in four towns (as mentioned previously in the literature review). None of the county agency case studies reported conduct- ing effectiveness evaluations. In all cases, the speed tran- sition measures were placed on two-lane, undivided roads with rural speed limits ranging from 45 mph to 55 mph (72 km/h to 88 km/h). The speed transitions required motorists to slow down by 15 mph to 30 mph (24 km/h to 48 km/h). A stepped-down speed was used in only two of the seven cases, and a description of the measures implemented was provided for only three of the case studies. All of the described treat- ments consisted of implementation of additional traffic con- trol devices, and are as follows: • Additional speed limit and advance alert signs on opposite side of road

55 • Approximately 500 ft (152 m) in advance of speed limit sign a large R2-4 [Ca.] 25 mph (40 km/h) Zone Ahead sign was placed. Then the actual speed limit, then approximately 250 ft (76 m), W11-2 on a fluorescent yellow-green sign was placed. • Installed intermediate speed limit of 40 mph (64 km/h).