Application of Crash Modification Factors for Access Management, Volume 2: Research Overview (2021) / Chapter Skim
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40 Introduction The objectives of Task 3 were to (1) design and conduct a survey to identify transportation agency policies, practices, needs, and challenges related to quantifying the safety effects of access management features and (2)
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Data Reconnaissance and Assessment 41 Summary of Initial Survey Responses Question 1: Do You Quantify the Safety Effects of Access Management Strategies To Support Related Decisions? Figure 14 shows that the majority of respondents do not quantify the safety e ects of access management strategies to support the decision-making process.
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42 Application of Crash Modification Factors for Access Management Question 2: Do You Have a Policy or Procedure for Assessing the Safety Effects of Access Management Strategies? Figure 15 shows that 23 of 28 respondents to Question 2 indicated that their agencies do not have a policy or procedure for assessing the safety effects of access management strategies.
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Data Reconnaissance and Assessment 43 Comments to this question from respondents answering "No" include the following: • "We have general policy, but not specifically to the safety effects of access management." • "Occasionally a researcher will gather data for some projects, but nothing that is routine." Question 3: Do You Track Safety-Related Performance Measures After Implementing Access Management Strategies? Question 3 (see Figure 16)
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44 Application of Crash Modification Factors for Access Management • "We have gone back and done some evaluations of access management projects, but we don't track these projects statewide." • ".
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Data Reconnaissance and Assessment 45 • "We attempt to use both of these elements, where applicable, equally." • "At this point, the majority of our focus is on individual strategies, making it a higher priority, but combination strategies would be helpful as well." • "Hard to pick one -- both are site specific and are needed." Question 5: What Are Your Priority Needs in Terms of the Level of Analysis? Question 5, shown in Figure 18, asked respondents to rank their priority needs from 1 to 3 (where 1 indicates the highest priority and 3 indicates the lowest)
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46 Application of Crash Modification Factors for Access Management Access Management Strategy 1 High Priority 2 Medium Priority 3 Low Priority Total Weighted Average % responding and number of responses Alternative intersection and interchange design 55% 16 34% 10 10% 3 29 2.45 Control driveway design elements 38% 11 38% 11 24% 7 29 2.14 Control intersection design elements 17% 5 48% 14 34% 10 29 1.83 Convert two-way streets to one-way operation 7% 2 24% 7 69% 20 29 1.38 Establish corner clearance criteria 28% 8 59% 17 14% 4 29 2.14 Improve cross connectivity 28% 8 45% 13 28% 8 29 2 Install continuous TWLTL on undivided highway 24% 7 55% 16 21% 6 29 2.03 Install left-turn lanes 28% 8 52% 15 21% 6 29 2.07 Install non-traversable medians and accommodate left turns and U-turns 61% 17 32% 9 7% 2 28 2.54 Install right-turn lanes 14% 4 41% 12 45% 13 29 1.69 Install service or frontage roads 14% 4 48% 14 38% 11 29 1.76 Manage location and spacing of unsignalized access 59% 17 38% 11 3% 1 29 2.55 Manage spacing of traffic signals 28% 8 48% 14 24% 7 29 2.03 Manage location, spacing, and design of median openings and crossovers 62% 18 28% 8 10% 3 29 2.52 Manage the spacing of signalized and unsignalized access on crossroads in the vicinity of freeway interchanges 55% 16 34% 10 10% 3 29 2.45 Provide adequate sight distance at access points 21% 6 48% 14 31% 9 29 1.9 Table 45. Survey summary: priority of access management strategies.
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Data Reconnaissance and Assessment 47 U-turns," "Manage location, spacing, and design of median openings and crossovers," "Manage the spacing of signalized and unsignalized access in the vicinity of freeway interchanges," and "Alternative intersection and interchange design." The five strategies with the highest weighted average are also the strategies that were ranked as "high priority" by a majority of respondents. The two strategies that followed the top five in terms of weighted average are "Control driveway design elements" and "Establish corner clearance criteria." Question 7: Are There Other Access Management Strategies or Combination(s)
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48 Application of Crash Modification Factors for Access Management • "My use of this analysis is not very frequent." • "Although ‘Install service or frontage roads' is low for our agency mostly to avoid maintenance costs, there is an incident management and network connectivity benefit that appears to not be accounted." • "This effort looks like it will be quite helpful as we continue to look at the benefit and costs of low cost/high benefit safety improvements. Thank You." Summary of Responses to Second Survey The survey was redistributed to local agencies and practitioners, including NACE, MPOs, and the ITE community.
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Data Reconnaissance and Assessment 49 Conclusions from the Survey The survey results indicated the following regarding the quantification and tracking of safety effects of access management strategies and the existence of policy or procedures for assessing these effects: • A majority of the respondents do not quantify the safety effects of access management strategies to support the decision-making process. • More than 80 percent of the respondents indicated that their agencies do not have a policy or procedure for assessing the safety effects of access management strategies.
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50 Application of Crash Modification Factors for Access Management the collection of additional variables related to access management. Similarly, datasets with highquality information on roadways and access management features (e.g., for a corridor-planning study)
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Data Source Level of Data (corridor, site, intersection) Variables in Dataset Miles or Locations by Facility Type Availability of Reference Sites Data Quality Agencies That Provided Data Notes DTFH61-09-C00026 Safety Evaluation of Access Management Policies and Techniques Corridor level.
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Data Source Level of Data (corridor, site, intersection) Variables in Dataset Miles or Locations by Facility Type Availability of Reference Sites Data Quality Agencies That Provided Data Notes NCHRP Project 17-62 Site and intersection level.
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NCHRP Project 17-70 Intersection – Roundabouts only Area type Circulating lanes Number of legs Posted speed limit Inscribed circle diameter Major and minor road AADT 355 sites Depending on approach and topic, a subset may be relevant as reference sites. High CA, FL, KS, MI, MN, NC, NY, ON, PA, WA, WI (2000–2014 depending on site)
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Data Source Level of Data (corridor, site, intersection) Variables in Dataset Miles or Locations by Facility Type Availability of Reference Sites Data Quality Agencies That Provided Data Notes Safety Analysis of Driveway Characteristics Along Major Urban Arterial Corridors in South Carolina.
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Safety Evaluation of Turning Movement Restrictions at Stop-Controlled Intersections. FHWA DCMF Project.
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