module 7 network screening · module 7: network screening module 7 ‐2 hsm training step 1....
TRANSCRIPT
Module 7: Network Screening
Module 7 ‐ 1HSM Training
MODULE 7. NETWORK SCREENINGHSM Vol. 1 (Part B) Chapter 4
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Roadway Safety
Management Process
Network Screening
Diagnosis and Countermeasure Selection
Economic Appraisal and Prioritization
Safety Effectiveness Evaluation
HSM Vol. 1 (Part B)Chapter 4
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Learning OutcomesNetwork Screening Process• Establish focus• Reference populations• Performance measures• Screening methods• Screening application
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Network Screening Process
STEP 1. Establish Focus
STEP 2. Identify Reference Populations
STEP 3. Select Performance Measures
STEP 4. Select Screening Methods
STEP 5. Screen and Evaluate Results
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Module 7: Network Screening
Module 7 ‐ 2HSM Training
Step 1. Establish Focus
• Overall crash reduction• Policy implementation
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Example Safety Policies and Programs
• Automated enforcement • Cable median barrier implementation• Public information programs (safety
belts, alcohol, young drivers, etc.)• Road departure (e.g. rumble strips)• High risk rural roads
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Focus Example Rumble Strip Applications
• Which sites can be improved with rumble strips?
• What is the target crash type? • Identify sites with high proportion of
run-off-road crashes• Apply rumble strips
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Vol. 1 (Part B) Case StudySignalized
Intersection Safety Program
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Module 7: Network Screening
Module 7 ‐ 3HSM Training
GIS Crash Mapping
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Step 2. Identify Reference Population
• Identify network elements to be screened– Intersections– Roadway segments– Facilities– Ramps– Ramp terminal intersections
• Organize by reference population
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Identify Reference Population
What is the reference population for implementing signalization treatments
(e.g., red-light cameras)?7-11
Step 3.Select Performance Measures
• Number of crashes• Crash severity• Critical crash rate• EPDO• Excess predicted crash frequency using
SPFs• Additional measures: Figure 4-4
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Module 7: Network Screening
Module 7 ‐ 4HSM Training
Selecting Performance Measures Key Criteria
• Data availability (see Table 4-1)– Crashes– Traffic volumes– Safety performance functions– Severity weighting factors
• Regression-to-the-mean bias• Performance threshold
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Candidate Site Database (5 yrs Crash Data)Location Crashes by Severity
Intersection Major Route Minor Route K A B C PDO1 Morris Blvd Chicago Ave 0 11 35 17 1942 Ist Avenue Golf Rd 0 10 33 37 2423 Devon Ave Main St 0 3 7 9 1004 3rd St Park Ave 0 4 6 10 605 Wilson Rd Lake St 0 0 1 5 486 Kennedy Blvd Main St 0 14 30 23 2487 Roosevelt Rd Lake St 0 0 1 3 258 5th St Chicago Ave 0 16 21 29 3819 Cicero Ave Banks Dr. 0 14 15 20 16510 Dawson Rd Howard St 0 0 1 9 40
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Mor
e D
ata;
Acc
ount
for R
TM B
ias
Gre
ater
Rel
iabi
lity
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Step 4.Select Screening Method
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• Sliding window• Peak searchingSegments
• Simple rankingIntersections
• Sliding window• Peak searching• Simple ranking
Corridors
Module 7: Network Screening
Module 7 ‐ 5HSM Training
Step 5.Screen / Evaluate Results
• Calculate performance measures for each segment or node
• Rank order
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Signalized Intersection Network Screening Overview
• Signalized Intersections
• Urban and Suburban
• State Routes Reference Population
• Crash Rate• EPDO• EPDO Expected Crash Frequency with EB Adjustment
Performance Measures • Simple
RankingScreening Method
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Crash Rate Performance and Rank
Intersection Total CrashesMillion Entering
VehiclesCrash Rate (CR) Rank
1 257 85 3.0 32 322 127 2.5 43 119 85 1.4 74 80 55 1.5 65 54 60 0.9 96 315 78 4.0 27 29 69 0.4 108 447 106 4.2 19 214 116 1.9 510 50 47 1.1 8
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EPDO Performance and Rank
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Intersection EPDO Score Rank
1 897 42 1135 13 312 64 283 75 115 96 996 37 70 108 1118 29 712 510 152 8
Module 7: Network Screening
Module 7 ‐ 6HSM Training
Expected Average Crash Frequency with EB Adjustments
Intersections 2, 6 and 8 selected for further study 7-21
IntersectionRanking
TotalCrashes
Fatal and Injury Crashes (KABC)
PDO crashes (O)
1 4 5 52 2 1 23 6 6 74 7 8 95 9 10 46 3 3 37 10 9 108 1 2 19 5 4 610 8 7 8
Roadway Safety Management
Process Overview
Network Screening
Diagnosis and Countermeasure
Selection
Economic Appraisal and Prioritization
Safety Effectiveness Evaluation
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MODULE 7. NETWORK SCREENINGSummary
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