A Multi Criteria Based Guideline for Marked and Unmarked Pedestrian Crosswalks at Unsignalized Intersections

Transcription

1 1 ITE Western District Annual Meeting A Multi Criteria Based Guideline for Marked and Unmarked Pedestrian Crosswalks at Unsignalized Intersections Zhao Yue Ph.D. Student, Research Assistant Department of Civil & Environmental Engineering July 15, 2013

2 2 Presentation Overview Introduction Research Objective Guideline Development Case Study Findings and Conclusions Future Work

3 3 Introduction UnMarked Crosswalks Increase With no clear pedestrian PATH for MOBILITY pedestrian With perhaps no specific a deceived WARNING sense for driver of SECURITY With HIGHER LOWER pedestrian crash rates (e.g. California, Florida, Texas and Nevada.) Typical Marked and Unmarked Crosswalks at TWSC Intersections

4 4 Introduction Critical Issues How effective a crosswalk marking could be? Whether crosswalk should be marked or not? Under what conditions marked crosswalks should be used? Geometry Characteristics Pedestrian Demand Accident Occurrence Mark vs. Unmark?

5 5 Introduction Existing Guidelines Descriptive statement; single dominate factor; point system ; flowchart; e.g. MUTCD, FHWA, etc. Major Issues of Existing Guidelines Rely on single factor Lack a balanced consideration and interpretation of all potential impact factors

6 6 Research Objective Develop a more applicable guideline to assist decision making, i.e. help determine the installation of marked crosswalks

7 7 Guideline Development Decision Making Process Attain a decision through the combination of impact factors simultaneously Multi Criteria Analysis Problem Alternatives: Mark, Unmark Multi criteria decisive variables: speed limit, number of travel lanes, traffic volumes, pedestrian demand, etc.,

8 8 Guideline Development Inner Computational Engine Combination of PROMETHEE &AHP

9 9 Guideline Development Step 1: Identify variables Variables Abbreviation Evaluation C1 Policy Preference Tendency PPT 0 N/A; 1 Conservative; 2 Moderate; 3 Aggressive C2 Current Crosswalk Condition MOU 0 Unmarked Crosswalk; 1 Marked Crosswalk C3 Geometry Layout of Intersection GL 3 Legs; 4 Legs C4 Number of Travel Lanes NTL 1 Lane; 2 Lanes; 3 Lanes and so forth C5 Available Gaps AG Average number of gaps per 5 minute period C6 Distance to Nearby Crosswalk DNC Unit: feet (ft) C7 Vehicle Speed Limit SL Unit: miles per hour (mph) C8 Traffic Volumes TV Unit: vehicles per hour (vph) C9 Pedestrian Volumes PV Unit: pedestrians per hour (peds/hour) C10 Pedestrian Accident Occurrence PRC Unit: accidents in 3 to 5 year period (acc./3 5 yrs)

10 10 Guideline Development Step 2: Determine weights for variables Dynamic and fluctuate according to different scenarios Scenarios N/A &, & / / & / & Otherwise/General Case

11 11 Guideline Development Step 3: Determine preference functions and degrees,,, 0, 1, 1,2,,, 1,2, 0 1 Preference Function Meaning Preference Function Meaning P M, U 0 no preference P U, M 0 no preference P M, U 0 weak preference for marking P U, M 0 weak preference for unmarking P M, U 1 strong preference of marking P U, M 1 strong preference of unmarking P M, U 1 strict preference of marking P U, M 1 strict preference of unmarking

12 12 Guideline Development Step 4: Determine ranking scores,, ;,,, ;,, ;, ; % % 2

13 13 Guideline Development Final Decision and Recommendations Decision Thresholds Criteria and Critical Thresholds Final Decision Additional Recommendations % a b c Mark Treatment Combinations % a d Unmark Other Design Elements % e Engineering Judgment Treatment Combinations and Roadway Design Elements a. 40 ; b. 1,200 ; c. 20 / ; d. 2; e. Combinations of variables C2 C10; Union of criteria.

14 Developed Guideline & Tool 14 Input existing information Run the model Recommendations

15 15 Case Study 24 unsignalized intersections: 50% marked crosswalks + 50% unmarked crosswalks

16 City of Henderson Input FHWA Existing Output GL PRC MT NTL SL PV TV Guideline Crosswalk Horizon Ridge Pkwy & Annet St Unmark N Unmark Burkholder & Cloudcrest Mark P Unmark Anthem & Atchley EJ P Mark Amador Lane & Hoskins Court Unmark P Unmark Paseo Verd & Bella Vista Apts Unmark N Unmark Developed Guideline & Tool Green Valley & Paseo Verd Mark C Mark Alexandria & Anthem Unmark N Mark Thunderbay & Sun City Anthem Unmark C Unmark Anthem & Somersworth Unmark N Mark Jada & Solera Sky Unmark P Unmark Millcroft & Clayton Unmark C Unmark Sunset Way & Valle Verde FHWA Guideline 210 Unmark P Mark High Mesa & Fountain Grove Unmark C Unmark Auto Mall & American Pacific Unmark N Unmark Democracy & Anthem Highlands Unmark P Mark Gibson & Mary Crest Unmark P Unmark Reunion Dr. & Cadence St Mark P Mark American Pacific Dr & Cassia Wy Existing 334 Crosswalk Unmark N Unmark Van Wagenen St & Victory Rd Unmark N Mark Center & Fir Mark C Unmark Wigwam & Grand Legacy Mark P Mark City of Reno Input FHWA Existing Output GL PRC MT NTL SL PV TV Guideline Crosswalk W Moana Ln & Smith Dr Unmark N Mark Sutro St & Oliver Ave Mark P Unmark N.Virginia & 17th St EJ P Unmark S Virginia University St & of La Nevada, Rue Ave Reno Mark P Mark 16

17 Case Study Phase I: Comparison of Developed Tool Recommendation and Existing Conditions 17 Approximate 72% of all proposals match actual crosswalk type 60% of FHWA recommendations confirm actual crosswalk type Percentages of Matching % 90.00% 80.00% 70.00% 60.00% 50.00% 40.00% 30.00% 59.66% 72.96% 64.45% 92.44% Explanation I: No consideration regarding pedestrian related crash factor in agencies when the crosswalk was installed % 10.00% 0.00% Field vs. FHWA Field vs. This Study FHWA vs. This Study FHWA vs. This Study* Comparison Categories

18 Case Study Phase I: Comparison of Developed Tool Recommendation and Existing Conditions 18 Explanation II: Final preference scores are not divided into absolute two categories, mark and unmark, but the engineering judgment category is highly recommended when the difference between two final scores is less than 20% % 90.00% 92.44% Percentages of Matching 80.00% 70.00% 60.00% 50.00% 40.00% 30.00% 59.66% 72.96% 64.45% 20.00% 10.00% 0.00% Field vs. FHWA Field vs. This Study FHWA vs. This Study FHWA vs. This Study* Comparison Categories

19 Case Study Phase II: Comparison of Developed Tool Recommendation and FHWA Guideline 19 64% of developed tool recommendations met FHWA recommendations. If merely considering combinations of vehicle ADT, speed limit and number of travel lanes which are the core of FHWA guideline, the developed guideline will provide the same results as FHWA guideline. By complementing pedestrian volume, crash data and engineer preference factors, developed tool could accommodate more practical and insightful suggestions pertaining to crosswalk type.

20 20 Findings and Conclusions Crosswalk marking is a useful traffic control device. It is very important to realize the positive as well as the negative consequences of marking crosswalks. The developed guideline and tool can help engineers make sound decisions for the placement of marked crosswalks and interpret the dilemma of crosswalk markings.

21 21 Future Work Crosswalk marking patterns Other treatments, e.g., red signal, beacon devices, crossing flags, etc.

22 22 Questions and Discussions Yue Zhao UNR CATER Civil & Environmental Engineering