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FHWA Home / Safety / Tools and Technology

Desktop Reference for Crash Reduction Factors

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Tables for Intersection Crash Reduction Factors

Table 1. Signalization Countermeasures

Countermeasures Crash Type Crash Severity Area Type Config Control Major Minor Ref Obs Effectiveness Study Type
Daily Traffic Volume (veh/day) Crash Reduction Factor/Function Std Error Range
Low High
Signal Operations Countermeasures
Add all-red clearance interval All All     Signal     15   15       Cross-section
Right-angle All     Signal     15   30       Cross-section
Add all-red clearance interval (from 0 to 1 second) Right-angle All Urban   Signal     47 6 0 44 -32 67  
Add exclusive pedestrian phasing Ped All     Signal     28   34   7 60  
Convert exclusive leading protected to exclusive lagging protected All All     Signal     25   -15 19     Simple Before-After
Left-turn All     Signal     25   -49 54     Simple Before-After
Convert protected left-turn phase to protected/permissive All All     Signal     25   -20 17     Comparison Group Before After
All Fatal/Injury     Signal     25   -10 25     Comparison Group Before After
Left-turn All     Signal     25   -65 71     Comparison Group Before After
Rear-end All     Signal     25   4 22     Comparison Group Before After
Convert protected/permissive left-turn phase to permissive/protected All All     Signal     29   13 19     Simple Before-After
Left-turn All     Signal     29   33 22     Simple Before-After
Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] All All   4-leg Signal     49   8 9     Experimental Design (Case-Control Study)
All All   4-leg Signal     39 20 18      
All Fatal/Injury   4-leg Signal     49   12 9     Experimental Design (Case-Control Study)
Head-on Fatal/Injury     Signal     15   75       Simple Before-After
Left-turn All     Signal     15   75        
Left-turn Fatal/Injury     Signal     15   55       Simple Before-After
Left-turn PDO     Signal     15   63       Simple Before-After
Multi-vehicle All All   Signal     21 40 5       Comparison Group Before After
Multi-vehicle Fatal/Injury All   Signal     21 40 9       Comparison Group Before After
ROR Fatal/Injury     Signal     15   62       Simple Before-After
ROR PDO     Signal     15   28       Simple Before-After
Older-driver All   4-leg Signal     39 20 42        
Rear-end All   4-leg Signal     49   -12 16     Experimental Design (Case Control Study)
Rear-end Fatal/Injury   4-leg Signal     49   -8 17     Experimental Design (Case Control Study)
Rear-end PDO     Signal     15   17       Simple Before-After
Right-angle All   4-leg Signal     49   4 18     Experimental Design (Case Control Study)
Right-angle Fatal/Injury     Signal     15   30       Simple Before-After
Right-angle Fatal/Injury   4-leg Signal     49   -6 22     Experimental Design (Case Control Study)
Right-angle PDO     Signal     15   46       Simple Before-After
Ped Fatal/Injury     Signal     49   37       Comparison Group Before After
Increase yellow change interval All All     Signal     15   15       Cross-section
Right-angle All     Signal     15   30       Cross-section
Install emergency vehicle pre-emption systems Emerg vehicle All           51   70        
Install pedestrian countdown signal heads Ped Fatal/Injury Urban (San Francisco)   Signal     32   25        
Install pedestrian signal All All     Signal     15   20        
All All           15   25        
All All           15   15        
Ped All     Signal     15   53        
Ped All     Signal     5   0        
Ped All           15   55        
Ped All           15   50        
Modify signal phasing (implement a leading pedestrian interval) Ped All     Signal     28   5        
Provide actuated signals Left-turn All     Signal     15   80       Cross-section
Right-angle All     Signal     15   10       Cross-section
Provide Advanced Dilemma Zone Detection for rural high speed approaches All Fatal/Injury Rural 4-leg (1 app) Signal     61 5 39       Simple Before-After
Provide protected left turn phase All All     Signal <5,000/lane (Total) 15   30       Simple Before-After
All All     Signal <5,000/lane (Total) 15   36       Simple Before-After
All All     Signal     15   15       Simple Before-After
All All     Signal     15   25       Cross-section
All All     Signal     15   30       Simple Before-After
All All     Signal     15   27        
Left-turn All     Signal <5,000/lane (Total) 15   41       Simple Before-After
Left-turn All     Signal >5,000/lane (Total) 15   46       Simple Before-After
Left-turn All     Signal     15   35       Simple Before-After
Left-turn All     Signal     15   70       Cross-section
Left-turn All     Signal     15   48        
Left-turn Fatal/Injury Urban   Signal     31 30 16 2     EB Before-After
Right-angle Fatal/Injury Urban   Signal     31 30 19 2     EB Before-After
Overturn All     Signal <5,000/lane (Total) 15   27       Simple Before-After
Overturn All     Signal >5,000/lane (Total) 15   35       Simple Before-After
Overturn All     Signal     15   31        
Ped All     Signal     28   5        
Rear-end All     Signal <5,000/lane (Total) 15   27       Simple Before-After
Rear-end All     Signal >5,000/lane (Total) 15   35       Simple Before-After
Rear-end All     Signal     15   31        
Right-angle All     Signal <5,000/lane (Total) 15   54       Simple Before-After
Right-angle All     Signal >5,000/lane (Total) 15   56       Simple Before-After
Right-angle All     Signal     15   80       Simple Before-After
Right-angle All     Signal     15   63        
Provide protected/permissive left-turn phase (leading flashing green) (Request MUTCD Experimentation) Left-turn Fatal/Injury Urban   Signal     31 15 16 4     EB Before-After
Right-angle Fatal/Injury Urban   Signal     31 15 12 4     EB Before-After
Provide protected left-turn phase (leading green arrow) Left-turn Fatal/Injury Urban   Signal     31 20 17 2     EB Before-After
Right-angle Fatal/Injury Urban   Signal     31 20 25 2     EB Before-After
Provide signal coordination All All All   Signal     1   15        
All All     Signal     28   16        
All All Arizona   Signal     3   7        
Right-angle All     Signal     28   32   25 38  
Provide split phases All All     Signal     28   25        
Remove flash mode (late night/early morning) All All     Signal     28   29        
Right-angle All     Signal     47 17 75 19 29 100 Simple Before-After
Right-angle All     Signal     28   80        
Replace existing WALK/DON'T WALK signals with pedestrian countdown signal heads Ped All Urban (San Francisco)   Signal     32   25        
SIGNAL HARDWARE COUNTERMEASURES
Add 3-inch yellow retroreflective sheeting to signal backplates All All Urban   Signal     54   15 51     EB Before-After
Add additional signal and upgrade to 12-inch lenses Older-driver All   4-leg Signal     39 33 31        
Younger-driver All   4-leg Signal     39 33 17        
Add signal (additional primary head) All All     Signal     28   10        
All All Urban 4-leg Signal     14 63 28   20 30 EB Before-After
All Fatal/Injury Urban 4-leg Signal     14 63 17   10 25 EB Before-After
All PDO Urban 4-leg Signal     14 63 31   30 35 EB Before-After
Rear-end All Urban 4-leg Signal     14 63 28   0 45 EB Before-After
Right-angle All     Signal     28   42        
Right-angle All Urban 4-leg Signal     14 63 35   15 45 EB Before-After
Convert signal from pedestal-mounted to mast arm All All     Signal     51   49        
All All empty cell   Signal     35 6 25       Simple Before-After
All All     Signal     35 33 32       Simple Before-After
All All     Signal     28   36   28 43  
All Fatal/Injury     Signal     51   44        
All PDO     Signal     51   51        
Left-turn All     Signal     51   12        
Rear-end All     Signal     51   41        
Right-angle All     Signal     51   74        
Right-angle All     Signal     35 6 63       Simple Before-After
Improve visibility of signal heads (increase signal lens size, install new backboards, add reflective tape to existing backboards, and/or install additional signal heads) All All Urban   Signal     52 224 7       EB Before-After
All Fatal/Injury Urban   Signal     52 224 3       EB Before-After
All PDO Urban   Signal     52 224 9       EB Before-After
Day All Urban   Signal     52 224 6       EB Before-After
Night All Urban   Signal     52 224 6       EB Before-After
Improve visibility of signal heads (install two red displays in each head) All All     Signal     28   9        
Right-angle All     Signal     28   36        
Install larger signal lenses (12 inch) All All All   Signal     1   10        
All All     Signal     28   11        
All All     Signal     15   10        
All All     Signal     15   10       Cross-section
All All     Signal     28   11   10 12  
All All Urban   Signal     54   24       Cross-section
All Fatal/Injury Urban   Signal     54   16       Cross-section
Right-angle All     Signal     47 44 46   -89 100 Simple Before-After
Right-angle All     Signal     28   48        
Install signal backplates only All All     Signal     28   13   2 24  
Right-angle All     Signal     28   50   7 93  
Install signal backplates (or visors) Right-angle All     Signal     15   20        
Right-angle All     Signal     15   20       Cross-section
Install signals All All     No signal <5,000/lane (Total) 15   38       Simple Before-After
All All     No signal >5,000/lane (Total) 15   20       Simple Before-After
All All     No signal     28   33   20 45  
Left-turn All     No signal     43 447 38       Simple Before-After
Right-turn All     No signal     43 447 50       Simple Before-After
All All Rural   No signal     43 447 15       Simple Before-After
All Fatal     No signal     43 447 38       Simple Before-After
Rear-end All     No signal     43 447 -48       Simple Before-After
Right-angle All     No signal     43 447 29       Simple Before-After
All All Urban   No signal     43 447 17       Simple Before-After
All All     No signal     15   22        
All All     No signal     15   15       Simple Before-After
All All     No signal     15   13       Simple Before-After
All All     No signal     15   20       Simple Before-Afer
All All     No signal     15   25       Cross-section
All All     No signal     15   20       Simple Before-After
All Fatal/Injury Urban 3-leg Stop 11,750-42,000 900-4,000 34   14 32     EB Before-After
All Fatal/Injury Urban 4-leg Stop 12,650-22,400, 2,400-3,625 34   23 22     EB Before-After
Overturn All     No signal <5,000/lane (Total) 15   22       Simple Before-After
Overturn All     No signal >5,000/lane (Total) 15   20       Simple Before-After
Rear-end All     No signal <5,000/lane (Total) 15   22       Simple Before-After
Rear-end All     No signal >5,000/lane (Total) 15   20       Simple Before-After
Rear-end Fatal/Injury Urban 3-leg Stop 11,750-42,000 900-4,000 34   -50 51     EB Before-After
Rear-end Fatal/Injury Urban 4-leg Stop 12,650-22,400 2,400-3,625 34   -38 39     EB Before-After
Right-angle All     No signal <5,000/lane (Total) 15   74       Simple Before-After
Right-angle All     No signal >5,000/lane (Total) 15   43       Simple Before-After
Right-angle All     No signal     15   58        
Right-angle All     No signal     15   60       Simple Before-After
Right-angle All     No signal     15   42       Simple Before-After
Right-angle All     No signal     15   65       Cross-section
Right-angle All     No signal     15   65       Simple Before-After
Right-angle All     No signal     28   68        
Right-angle All     No signal     47 8 74 66 56 100 Simple Before-After
Right-angle Fatal/Injury Urban 3-leg Stop 11,750-42,000 900-4,000 34   34 45     EB Before-After
Right-angle Fatal/Injury Urban 4-leg Stop 12,650-22,400 2,400-3,625 34   67 20     EB Before-After
All PDO     No signal     43 447 -15       Simple Before-After
Install signals (temporary) Head-on PDO     No signal     15   83       Simple Before-After
Left-turn PDO     No signal     15   11       Simple Before-After
Right-angle Fatal/Injury     No signal     15   39       Simple Before-After
Right-angle PDO     No signal     15   73       Simple Before-After
Sideswipe Fatal/Injury     No signal     15   50       Simple Before-After
Install signals (to have one over each approach lane) Right-angle All All         35   46       Simple Before-After
Remove unwarranted signals All All     Signal     15   75        
All All     Signal     15   100       Simple Before-After
All All     Signal     15   50       Cross-section
All All     Signal     15   75       Simple Before-After
All All     Signal     28   52   50 53  
All All Urban   Signal     21 199 24       EB Before-After
All Fatal/Injury Urban   Signal     21 199 53       EB Before-After
All PDO Urban   Signal     21 199 24       EB Before-After
Day All Urban   Signal     21 199 22       EB Before-After
Fixed object All Urban   Signal     21 199 31       EB Before-After
Night All Urban   Signal     21 199 30       EB Before-After
Rea-end All     Signal     15   95   90 100  
Rear-end All     Signal     15   100       Simple Before-After
Rear-end All     Signal     15   90       Cross-section
Rear-end All Urban   Signal     21 199 29       EB Before-After
Right-angle All Urban   Signal     21 199 24       EB Before-After
Replace signal lenses with optical lenses All All     Signal     28   17   15 18  
All All     Signal     15   15        
All All     Signal     15   15       Cross-section
Head-on All     Signal     15   20       Cross-section
Left-turn All     Signal     15   10       Cross-section
Rear-end All     Signal     15   10       Cross-section
Right-angle All     Signal     15   10       Cross-section
COMBINATION SIGNAL AND OTHER COUNTERMEASURES
Install left-turn lane and add turn phase All All     Signal     28   58   46 69  
Install signals and add channelization Head-on PDO     No signal     15   27       Simple Before-After
Left-turn PDO     No signal     15   24       Simple Before-After
ROR Fatal/Injury     No signal     15   35       Simple Before-After
Right-angle Fatal/Injury     No signal     15   67       Simple Before-After
Right-angle PDO     No signal     15   63       Simple Before-After
Sideswipe Fatal/Injury     No signal     15   54       Simple Before-After
LEFT-TURN COUNTERMEASURES
Add indirect left-turn treatments to minimize conflicts All All     Stop >34,000   59   18 8     Cross-section
All All     Stop >34,000 4 lanes   59   -24 35     Cross-section
All All     Stop >34,000 6 lanes   59   26 8     Cross-section
All All     Stop >34,000 8 lanes   59   24 63     Cross-section
All Fatal/Injury     Stop >34,000   59   27 12     Cross-section
All PDO     Stop >34,000   59   6 11     Cross-section
Create directional median openings to allow left-turns and u-turns All All     Signal     51   51        
Install left-turn lane All All All         1   25        
All All Rural 3-leg Signal 4,200-26,000 1,300-11,400 22 199 15       Expert Panel
All All Rural 3-leg Stop 1,100-32,400 25-11,800 22   44 6     EB Before-After
All All Rural 4-leg (app) Signal 4,200-26,000 1,300-11,400 22 199 18       Expert Panel
All All Rural 4-leg (1 app) Stop 1,100-32,400 25-11,800 22   28 3     EB Before-After
All All Rural 4-leg (2 app) Stop 1,100-32,400 25-11,800 22   48 3     EB Before-After
All All     No signal     15   34        
All All     No signal     15   35       Simple Before-After
All All     No signal     15   35       Cross-section
All All     No signal     15   25       Simple Before-After
All All     No signal     15   40       Simple Before-After
All All     No signal     28   33   25 41  
All All Urban 3-leg Signal 4,600-55,100 100-26,000 22 199 7       Expert Panel
All All Urban 3-leg Stop 1,520-40,600 80-8,000 22   33 12     EB Before-After
All All Urban 4-leg (1 app) Signal 4,600-55,100 100-26,000 22   10 10     EB Before-After
All All Urban 4-leg (1 app) Stop 1,520-40,600 80-8,000 22   27 3     EB Before-After
All All Urban 4-leg (2 app) Signal 4,600-55,100 100-26,000 22   19 13     EB Before-After
All All Urban 4-leg (2 app) Stop 1,520-40,600 80-8,000 22   47 4     EB Before-After
All Fatal/Injury Rural 3-leg Stop 1,100-32,400 25-11,800 22   55 8     EB Before-After
All Fatal/Injury Rural 4-leg (1 app) Stop 1,100-32,400 25-11,800 22   35 3     EB Before-After
All Fatal/Injury Rural 4-leg (2 app) Stop 1,100-32,400 25-11,800 22   58 4     EB Before-After
All Fatal/Injury Urban 4-leg (1 app) Signal 4,600-55,100 100-26,000 22   9 1     EB Before-After
All Fatal/Injury Urban 4-leg (1 app) Stop 1,520-40,600 80-8,000 22   29 4     EB Before-After
All Fatal/Injury Urban 4-leg (2 app) Signal 4,600-55,100 100-26,000 22   17 2     EB Before-After
All Fatal/Injury Urban 4-leg (2 app) Stop 1,520-40,600 80-8,000 22   50 6     Comparison Group
All Fatal/Injury All All All     58   30        
Left-turn All Rural 3-leg Stop 1,100-32,400 25-11,800 21 35 62       Comparison Group Before After
Left-turn All Rural 4-leg (1 app) Stop 1,100-32,400 25-11,800 21 23 37       EB Before-After
Left-turn All Rural 4-leg (2 app) Stop 1,100-32,400 25-11,800 21 23 60       EB Before-After
Left-turn All     No signal     15   55        
Left-turn All     No signal     15   55       Simple Before-After
Left-turn All     No signal     28   68   50 86  
Left-turn All     Signal >5,000/lane (Total) 15   24       Simple Before-After
Left-turn All Urban 4-leg (1 app) Signal 4,600-55,100 100-26,000 21 35 13       Yorked Comparison Before-After
Left-turn All Urban 4-leg (1 app) Stop 1,520-40,600 80-8,000 21 7 26       EB Before-After
Left-turn All Urban 4-leg (2 app) Signal 4,600-55,100 100-26,000 21 35 24       Yorked Comparison Before-After
Left-turn All Urban 4-leg (2 app) Stop 1,520-40,600 80-8,000 21 7 45       EB Before-After
Night All     Signal >5,000/lane (Total) 15   28       Simple Before-After
Overturn All     Signal >5,000/lane (Total) 15   28       Simple Before-After
Install left-turn lane (double) Heads-on Fatal/Injury       empty cell 15   75       Simple Before-After
Left-turn Fatal/Injury       empty cell 15   47       Simple Before-After
Left-turn PDO       empty cell 15   71       Simple Before-After
ROR Fatal/Injury       empty cell 15   8       Simple Before-After
ROR PDO       empty cell 15   13       Simple Before-After
Rear-end Fatal/Injury       empty cell 15   29       Simple Before-After
Rear-end PDO       empty cell 15   32       Simple Before-After
Right-angle Fatal/Injury       empty cell 15   20       Simple Before-After
Right-angle PDO       empty cell 15   8       Simple Before-After
Sideswipe Fatal/Injury       empty cell 15   50       Simple Before-After
Install left-turn lane (painted separation) All All empty cell empty cell   <5,000/lane (Total) 15   50       Simple Before-After
All Fatal/Injury Rural 3-leg   5,000-15,000   13   22 14     Meta-analysis
All Fatal/Injury Rural 4-leg   5,000-15,000   13   -28 27     Meta-analysis
All PDO Rural 3-leg   5,000-15,000   13   20 19     Meta-analysis
All PDO Rural 4-leg   5,000-15,000   13   26 12     Meta-analysis
Left-turn All       <5,000/lane (Total) 15   57       Simple Before-After
Left-turn All       >5,000/lane (Total) 15   35       Simple Before-After
Overturn All       <5,000/lane (Total) 15   54       Simple Before-After
Overturn All       >5,000/lane (Total) 15   39       Simple Before-After
Rear-end All       <5,000/lane (Total) 15   54       Simple Before-After
Rear-end All       >5,000/lane (Total) 15   39       Simple Before-After
Right-angle All       <5,000/lane (Total) 15   62       Simple Before-After
Right-angle All       >5,000/lane (Total) 15   49       Simple Before-After
Install left-turn lane (physical channelization) All All All   No signal     1   35        
All All All   Signal empty cell 1   25        
All All Rural 3-leg No signal empty cell 28   44        
All All Rural 4-leg (1 app) No signal empty cell 28   28        
All All   4-leg (2 app) No signal empty cell 28   42        
All All       <5,000/lane (Total) 15   51       Simple Before-After
All All       >5,000/lane (Total) 15   19       Simple Before-After
All All Urban 3-leg No signal empty cell 28   33        
All All Urban 4-leg (1 app) No signal empty cell 28   27        
All Fatal/Injury Rural 3-leg   5,000-15,000   13   27 13     Meta-analysis
All Fatal/Injury Rural 4-leg   5,000-15,000   13   4 12     Meta-analysis
All PDO Rural 3-leg   5,000-15,000   13   -20 23     Meta-analysis
All PDO Rural 4-leg   5,000-15,000   13   16 22     Meta-analysis
Left-turn All       <5,000/lane (Total) 15   24       Simple Before-After
Left-turn All       >5,000/lane (Total) 15   24       Simple Before-After
Left-turn Fatal/Injury       empty cell 15   50       Simple Before-After
ROR PDO       empty cell 15   50       Simple Before-After
Overturn All       <5,000/lane (Total) 15   50       Simple Before-After
Overturn All       >5,000/lane (Total) 15   28       Simple Before-After
Rear-end All       <5,000/lane (Total) 15   50       Simple Before-After
Rear-end All       >5,000/lane (Total) 15   28       Simple Before-After
Rear-end Fatal/Injury       empty cell 15   11       Simple Before-After
Rear-end PDO       empty cell 15   56       Simple Before-After
Right-angle All       <5,000/lane (Total) 15   68       Simple Before-After
Right-angle All       >5,000/lane (Total) 15   55       Simple Before-After
Right-angle Fatal/Injury       empty cell 15   58       Simple Before-After
Right-angle PDO       empty cell 15   54       Simple Before-After
Install left-turn lane (signal has left-turn phase) All All     Signal     28   31   25 36  
All All     Signal     51   35        
Left-turn All     Signal     28   44   43 45  
Older-driver head on All   4-leg Signal     39 13 73        
Younger-driver head on All   4-leg Signal     39 13 63        
Install left-turn lane (signal has no turn phase) All All     Signal     28   23   21 25  
Left-turn All     Signal     28   50   46 54  
Install left-turn lane (with channelization and existing left-turn phase) All All     Signal     15   35        
All All     Signal     15   35       Simple Before-After
All All     Signal     15   35       Cross-section
Install left-turn lane (with channelization and no left-turn phase) All All           15   15        
All All           15   15       Simple Before-After
All All           15   15       Cross-section
Install left-turn lane (within existing curbs) All All     Signal     28   26        
Left-turn All     Signal     28   66        
Install left-turn refuge within flush median All All       <5,000/lane (Total) 15   24       Simple Before-After
All All       >5,000/lane (Total) 15   44       Simple Before-After
Head-on All       >5,000/lane (Total) 15   52       Simple Before-After
Left-turn All       >5,000/lane (Total) 15   77       Simple Before-After
Overturn All       <5,000/lane (Total) 15   44       Simple Before-After
Overturn All       >5,000/lane (Total) 15   40       Simple Before-After
Rear-end All       <5,000/lane (Total) 15   44       Simple Before-After
Rear-end All       >5,000/lane (Total) 15   40       Simple Before-After
Sideswipe All       >5,000/lane (Total) 15   52       Simple Before-After
Remove left-turn lane All All Rural 3-leg Signal empty cell 6   -18        
All All Rural 4-leg (1 app) Signal empty cell 6   -22        
All All Rural 4-leg (2 app) Signal empty cell 6   -49        
All All Urban 3-leg Signal empty cell 6   -8        
All All Urban 3-leg Stop empty cell 6   -49        
All All Urban 4-leg (1 app) Signal empty cell 6   -11        
All All Urban 4-leg (1 app) Stop empty cell 6   -37        
All All Urban 4-leg (2 app) Signal empty cell 6   -23        
All All Urban 4-leg (2 app) Stop empty cell 6   -88        
All Fatal/Injury Rural 3-leg Signal empty cell 6   -16        
All Fatal/Injury Rural 4-leg (1 app) Signal empty cell 6   -21        
All Fatal/Injury Rural 4-leg (2 app) Signal empty cell 6   -45        
All Fatal/Injury Urban 3-leg Signal empty cell 6   -6        
All Fatal/Injury Urban 3-leg Stop empty cell 6   -53        
All Fatal/Injury Urban 4-leg (1 app) Signal empty cell 6   -10        
All Fatal/Injury Urban 4-leg (1 app) Stop empty cell 6   -41        
All Fatal/Injury Urban 4-leg (2 app) Signal empty cell 6   -21        
All Fatal/Injury Urban 4-leg (2 app) Stop empty cell 6   -98        
RIGHT-TURN COUNTERMEASURES
Increase length of right-turn lane All Fatal/Injury All All All     58   15        
Install right-turn lane All All All 4-leg (1 app) Signal 4,200-55,100 100-26,000 22   4 2     EB Before-After
All All All 4-leg (1 app) Stop 1,100-40,600 25-11,800 22   14 5     EB Before-After
All All All 4-leg (2 app) Signal 4,200-55,100 100-26,000 22   8 3     EB Before-After
All All All 4-leg (2 app) Stop 1,100-40,600 25-11,800 22   26 7     EB Before-After
All All All All All     58   35        
All All All         1   25        
All All Rural 4-leg (1 app) Signal     28   14        
All All Rural 4-leg (1 app) No signal     28   21   14 27  
All All   All No signal     28   27   24 30  
All All           15   25        
All All           15   25       Cross-section
All All           15   25       Simple Before-After
All All           15   25       Simple Before-After
All Fatal/Injury All 4-leg (1 app) Signal 4,200-55,100 100-26,000 22   9 3     EB Before-After
All Fatal/Injury All 4-leg (1 app) Stop 1,100-40,600 25-11,800 22   23 7     EB Before-After
All Fatal/Injury All All No signal     58   35        
All Fatal/Injury All All Signal     58   35        
All Fatal/Injury All All       51   40        
All Fatal/Injury Rural All All     58   35        
All Fatal/Injury Urban All All     58   30        
Rear-end All           15   65       Simple Before-After
Right-angle All           15   50       Simple Before-After
Right-turn All           15   53        
Right-turn All           15   56       Simple Before-After
Right-turn All           15   50       Cross-section
Sideswipe All           15   20       Simple Before-After
Install right-turn lane (painted separation) All Fatal/Injury All All All     58   30        
Install right-turn lane (physical channelization) All Fatal/Injury All All All     58   35        

Table 2. Geometric Countermeasures

Countermeasures Crash Type Crash Severity Area Type Config Control Major Minor Ref Obs Effectiveness Study Type
Daily Traffic Volume (veh/day) Crash Reduction Factor/Function Std Error Range
Low High
OTHER GEOMETRIC COUNTERMEASURES
Convert four-leg to two T-intersections All All   4-leg No signal     28   57        
All Fatal/Injury Urban 4-leg   <70%* >30%* 13   33 6     Meta-analysis
All Fatal/Injury Urban 4-leg   >85%* <15%* 13   -35 15     Meta-analysis
All Fatal/Injury Urban 4-leg   70-85%* 15-30%* 13   25 5     Meta-analysis
All PDO Urban 4-leg   <70%* >30%* 13   10 5     Meta-analysis
All PDO Urban 4-leg   >85%* <15%* 13   -15 6     Meta-analysis
All PDO Urban 4-leg   70-85%* 15-30%* 13   0 5     Meta-analysis
All All   4-leg       51   57       Meta-analysis
Convert intersection to roundabout All All All   All     50 55 35 3     EB Before-After
All All All   Signal     50 9 48 5     EB Before-After
All All All   Signal     21 23 40       EB Before-After
All All All   Stop (2-way)     50 36 44 4     EB Before-After
All All All   Stop (4-way)     50 10 -3 15     EB Before-After
All All Rural 1-lane Stop (2-way)     50 9 72 4     EB Before-After
All All Rural   Stop 7,185-17,220   44   58 7     EB Before-After
All All   3-leg       15   50       Simple Before-After
All All   4-leg       15   75       Simple Before-After
All Fatal/Injury           55 181 65       Simple Before-After
All PDO           55 181 42       Simple Before-After
Ped All           55 181 89       Simple Before-After
All All Urban   Stop 13,272-30,418   44   5 10     EB Before-After
All All Urban   Signal 5,322-31,525   44   35 9     EB Before-After
All All Urban   Signal     50 5 1 12     EB Before-After
All All Urban   Signal     21 4 35       EB Before-After
All All Urban   Stop (2-way)     50 27 31 6     EB Before-After
All All Urban 1-lane Stop (2-way)     50 16 56 6     EB Before-After
All All Urban 2-lane Signal     50 4 67 4     EB Before-After
All All Urban 2-lane Stop (2-way)     50 11 18 8     EB Before-After
All All Urban   Stop 4,600-17,825   44   72 6     EB Before-After
All Fatal/Injury All   All     50 55 76 3     EB Before-After
All Fatal/Injury All   Signal     50 9 78 6     EB Before-After
All Fatal/Injury All   Stop (2-way)     50 36 82 3     EB Before-After
All Fatal/Injury All   Stop (4-way)     50 10 -28 41     EB Before-After
All Fatal/Injury All   All     21 23 80       EB Before-After
All Fatal/Injury Rural 1-lane Stop (2-way)     50 9 87 3     EB Before-After
All Fatal/Injury Rural   Stop 7,185-17,220   44   82 9     EB Before-After
All Fatal/Injury     No signal     11 62 44   34 52 EB and Meta-analysis
All Fatal/Injury     Signal     11 34 32   19 43 EB and Meta-analysis
All Fatal/Injury           11 96 39   31 45 EB and Meta-analysis
All Fatal/Injury Urban   Signal     50 5 60 12     EB Before-After
All Fatal/Injury Urban   Stop (2-way)     50 27 74 6     EB Before-After
All Fatal/Injury Urban 1-lane Stop (2-way)     50 16 78 7     EB Before-After
All Fatal/Injury Urban 2-lane Stop (2-way)     50 11 72 9     EB Before-After
All Fatal/Injury Urban   Signal 5,322-31,525   44   74 14     EB Before-After
All Fatal/Injury Urban   Stop 4,600-17,825   44   88 8     EB Before-After
Ped Fatal/Injury empty cell   No signal     11   27        
Ped Fatal/Injury     Signal     11   -28        
Improve intersection alignment (reduce skew) All All Rural 3-leg Stop     6   100(1-EXP(0.0048*|intersection angle - 90º|)); angle in degrees  
All All Rural 4-leg Stop     6   100(1-EXP(0.0054*|intersection angle - 90º|)); angle in degrees  
Improve sight distance in 1 quadrant All All Rural 4-leg Stop/Yield (2-way)     23   5       Expert Panel
Improve sight distance in 2 quadrants All All Rural 4-leg Stop/Yield (2-way)     23   9        
Improve sight distance in 3 quadrants All All Rural 4-leg Stop/Yield (2-way)     23   13        
Improve sight distance in 4 quadrants All All Rural 4-leg Signal     23   0        
All All Rural 4-leg Stop/Yield (2-way)     23   17        
Improve sight distance to intersection All Fatal           51   56        
All Injury           51   37        
Increase median width by 3 ft Multiple-vehicle All Rural 4-leg Stop     24   4 1     Cross-section
Multiple-vehicle All Urban 3-leg Stop     24   -3 1     Cross-section
Multiple-vehicle All Urban 4-leg Signal     24   -3 1     Cross-section
Multiple-vehicle All Urban 4-leg Stop     24   -6 1     Cross-section
Multiple-vehicle Fatal/Injury Rural 4-leg Stop     24   4 1     Cross-section
Multiple-vehicle Fatal/Injury Urban 4-leg Signal     24   -3 1     Cross-section
Multiple-vehicle Fatal/Injury Urban 4-leg Stop     24   -5 1     Cross-section
Increase pedestrian storage area at corner All Fatal/Injury           5   -12 126     Meta-analysis
Install median All All Rural   Stop     6   27        
Install median islands (painted) on major road approaches All Fatal/Injury All All All     58   15        
Install median islands (physical) on major road approaches All Fatal/Injury All All All     58   25        
Install raised median All All     No signal     28   25        
All All           28   25        
Ped All     No signal     28   69        
Install raised median (marked crosswalk) Ped All           60   46        
Install raised median (unmarked crosswalk) Ped All           60   39        
Install refuge islands Peds All           28   56        
Install splitter islands on minor road approaches All Fatal/Injury All 3-leg All     58   45        
All Fatal/Injury All 4-leg All     58   40        
All Fatal/Injury All All All     58   40        
All Fatal/Injury Rural All All     58   35        
All Fatal/Injury Urban All All     58   40        
Install turn and bypass lanes All All Rural   Stop     48   5 10     Simple Before-After
Head-on PDO   3-leg       15   13       Simple Before-After
Left-turn Injury   3-leg       15   36       Simple Before-After
Left-turn PDO   3-leg       15   28       Simple Before-After
ROR PDO   3-leg       15   40       Simple Before-After
Rear-end Injury   3-leg       15   18       Simple Before-After
Rear-end PDO   3-leg       15   21       Simple Before-After
Right-angle Injury   3-leg       15   24       Simple Before-After
Right-angle PDO   3-leg       15   53       Simple Before-After
Sideswipe PDO   3-leg       15   30       Simple Before-After
Vary median width All All Rural   Stop     6   100(1-EXP(-0.012(Wm-16))); Wm=median width (ft)  
All All Urban 3-leg Stop     6   100(1-EXP(0.0082(Wm-16))) for Wm>16 1.0 for Wm<=16; Wm=median width (ft)  
All All Urban 4-leg Stop     6   100(1-EXP(0.0173(Wm-16))) for Wm>16 1.0 for Wm<=16; Wm=median width (ft)  
All Fatal/Injury Urban 3-leg Stop     6   100(1-EXP(0.0076(Wm-16))) for Wm>16 1.0 for Wm<=16; Wm=median width (ft)  
All Fatal/Injury Urban 4-leg Stop     6   100(1-EXP(0.016(Wm-16))) for Wm>16 1.0 for Wm<=16; Wm=median width (ft)  
Vary shoulder width All All Rural 3-leg and 4-leg Stop     6   100(1-EXP(-0.03(Ws-8)); Ws=outside shoulder width (ft)  
All All Urban   Stop     6   100(1-EXP(-0.02(Ws-1.5)); Ws=outside shoulder width (ft)  
* Percentage of Total Daily Traffic Volume

Table 3. Signs/Markings/Operational Countermeasures

Countermeasures Crash Type Crash Severity Area Type Config Control Major Minor Ref Obs Effectiveness Study Type
Daily Traffic Volume (veh/day) Crash Reduction Factor/Function Std Error Range
Low High
SIGNS
Install double stop signs All All     No signal     28   11        
Right-angle All     No signal     47 10 55 52 -38 100 Simple Before-After
Right-angle All     No signal     28   36        
Install flashing beacons as advance warning All All   3-leg       15   70       Simple Before-After
All All   4-leg       15   39       Simple Before-After
All All     Signal     28   27   25 28  
All All           15   25        
All All           15   25       Cross-section
All All           15   27       Simple Before-After
All All           15   25       Simple Before-After
Left-turn Fatal/Injury           15   67       Simple Before-After
Left-turn PDO           15   79       Simple Before-After
Rear-end All   4-leg Signal     39   36        
Right-angle All   4-leg Signal     39   62        
Right-angle Fatal/Injury           15   73       Simple Before-After
Right-angle Fatal/Injury           15   73       Simple Before-After
Right-angle PDO           15   62       Simple Before-After
Install larger stop signs All All     Stop >5,000/lane (Total) 15   19       Simple Before-After
Install pedestrian signing All All       empty cell 15   4        
Ped All       empty cell 15   15        
Install advance warning signs (positive guidance) All All All     empty cell 1   35        
All All     Signal empty cell 28   22   3 40  
All All Urban     empty cell 15   30       Cross-section
All All Rural     empty cell 15   40        
Right-angle All     Signal empty cell 47 11 35   20 100 Simple Before-After
Right-angle All     Signal empty cell 28   35        
Provide overhead lane-use signs Rear-end All       empty cell 51   10        
Sideswipe All       empty cell 51   20        
PAVEMENT MARKINGS/MODIFICATIONS
Add centerline and move STOP bar to extended curb lines All All     No signal     28   29        
Right-angle All     No signal     28   24        
Add centerline and move STOP bar to extended curb lines, double stop signs All All     No signal     28   9        
Right-angle All     No signal     28   0        
Add centerline and STOP bar, replace 24-inch with 30-inch stop signs Right-angle All     No signal     47   67 11 27 100 Simple Before-After
Right-angle All     No signal     28   67        
Improve pavement friction (groove) All All           28   25        
Wet All           28   59   42 75  
Improve/install pedestrian crossing All All           15   25        
Ped All           15   25        
Install pedestrian crossing Ped All           15   25        
Ped All           15   25        
Ped Fatal/Injury Rural         38   60       EB Before-After
Install pedestrian crossing (raised) All All           5   30 67     Meta-analysis
All Fatal/Injury           5   36 54     Meta-analysis
Ped All           28   8        
Install raised intersection All Fatal/Injury   4-leg       13   -5       Meta-analysis
All PDO   4-leg       13   -13       Meta-analysis
Install raised pavement markers All All           28   10   6 13  
Wet All           28   25   20 30  
Wet/Night All           28   33   20 16  
Install STOP bars (pedestrian crosswalk) All All     Signal     28   18   10 25  
Install STOP bars (STOP bar on minor road approaches, with short segments of centerline) All All           28   19   10 27  
Right-angle All           28   47        
Install transverse pavement markings All All           15   18       Simple Before-After
Speed-related Fatal/Injury     Stop     18   57 8     Simple Before-After
Speed-related Serious injury     Stop     18   74 13     Simple Before-After
Speed-related Slight injury     Stop     18   52 11     Simple Before-After
Speed-related and day All     Stop     18   66 8     Simple Before-After
Speed-related and dry All     Stop     18   45 15     Simple Before-After
Speed-related All     Stop     18   48 14     Simple Before-After
Speed-related and wet All     Stop     18   68 11     Simple Before-After
Install transverse rumble strips on approaches All All Rural   No signal     28   35        
All All     Stop     15   28       Simple Before-After
All All           28   23   2 44  
Rear-end All           15   90       Simple Before-After
Mark pavement with supplementary warning messages All All empty cell   No signal     28   6        
Right-angle All     No signal     28   30        
Right-angle All Urban   Stop     47 5 30 66 -20 100 Simple Before-After
Provide bicycle box (advance stop bar to leave dedicated space for cyclists) Bicycle All     Signal     51   36        
Provide bike lanes Bicycle All           51   36        
Resurface pavement All All           28   33   7 59  
Wet All           28   47   42 75  
REGULATORY
Convert STOP control to Yield control All All All   Stop     21 141 -137       Comparison Group Before After
All All Urban 4-leg Stop     33   -127 70     Comparison Group Before After
Convert to all-way STOP control (from 2-way control) All All All   Stop     21 360 47       Before-After with Likelihood Functions
All All     No signal     28   64   53 74  
All All     Stop     15   53        
All Fatal/Injury Urban   Stop     30   71 6     Simple Before-After
Left-turn All Urban   Stop     30   20 52     Simple Before-After
Left-turn All     Stop     15   20       Cross-section
Ped All           15   39        
Ped All Urban   Stop     30   39 8     Before-After
Rear-end All Urban   Stop     30   13 13     Simple Before-After
Rear-end All     Stop     15   13       Cross-section
Right-angle All Urban   Stop     30   72 3     Simple Before-After
Right-angle All     No signal     28   84        
Right-angle All     Stop     15   72       Cross-section
Right-angle All Urban   Stop     47 10 80 41 49 100 Simple Before-After
Convert two-way to one-way roadway All All           15   26        
All All           15   26       Cross-section
Convert Yield control to STOP control All All     No signal     28   29        
Right-angle All     No signal     28   9        
Install no left-turn and no u-turn signs All All Urban     19,435-42,000 (Total) 7   62 6     Simple Before-After
Left-turn (or u-turn) All Urban     19,435-42,000 (Total) 7   59 5     Simple Before-After
Permit right-turn-onred All All     Signal empty cell 5   -7 1     Simple Before-After
All All     Signal empty cell 10   -5 1     Simple Before-After
Ped All New Orleans   Signal empty cell 5   -81 88     Before-After
Ped All New York   Signal empty cell 5   -43 24     Before-After
Ped All Ohio   Signal empty cell 5   -57 31     Before-After
Ped All Wisconsin   Signal empty cell 5   -108 51     Before-After
Right-turn Fatal/Injury     Signal empty cell 13   -60 5     Meta-analysis
Right-turn PDO     Signal empty cell 13   -10 1     Meta-analysis
Prohibit left-turns All All       empty cell 15   -45        
All All       empty cell 15   45       Cross-section
Left-turn All       empty cell 15   90       Cross-section
Ped All       empty cell 15   10        
Rear-end All       empty cell 15   30       Cross-section
Prohibit right-turn-onred All All     Signal empty cell 28   23   20 25  
ROR All     Signal empty cell 15   30       Cross-section
Rear-end All     Signal empty cell 15   20       Cross-section
All All Urban/suburban   Signal empty cell 62   100(1-(0.984)^n); n=number of signalized intersection appraoches where RTOR is prohibited Expert Panel
Right-angle All     Signal empty cell 15   30       Cross-section
Sideswipe All     Signal empty cell 15   20       Cross-section
Prohibit turns All turns All All     empty cell 1   45   40 90  
Restrict parking near intersections (to offstreet) All All empty cell     empty cell 28   49   8 90  
Ped All       empty cell 15   30        
Vary speed All All Rural     empty cell 6   100(1-EXP(0.019(V-55))); V=majorroad speed limit (or design speed) (mph)  
All All Urban     empty cell 6   100(1-EXP(0.005(V-40))); V=majorroad speed limit (or design speed) (mph)  
LIGHTING
Improve lighting at intersection Ped Fatal           5   78 87      
Ped Injury           5   42 18      
Install lighting All All     Signal     51   30        
All Fatal/Injury     Signal     51   17        
Night All     Signal     51   50        
All All     No signal     28   47        
OPERATIONAL
Convert STOP control (2-way) to signal control All All     Stop     15   28       Cross-section
All Injury     Stop     15   43       Cross-section
Right-angle All     Stop     15   74       Cross-section
Convert STOP control (2-way) to signal control and install left-turn lane All All     Stop     15   36       Cross-section
All Injury     Stop     15   53       Cross-section
Rear-end All     Stop     15   8       Cross-section
Right-angle All     Stop     15   74       Cross-section
Increase enforcement to reduce speed Ped All           28   70        
Install angled median crosswalk All All           28   12        
Install beacon (flashing) at intersection All All All         1   30   7 50  
All All All         1   30        
All All     Signal     28   34   30 38  
All All           15   30        
All All           15   30       Cross-section
All All           15   4       Simple Before-After
All All           15   30       Simple Before-After
Install cameras to detect red-light running All All     Signal 17,000-78,000   37 46 -12 5     EB Before-After
All All Urban (Scottsdale)   Signal     56   11       EB Before-After
All Fatal/Injury All All Signal     58   5        
All Fatal/Injury     Signal 17,000-78,000   37 46 -14 9     EB Before-After
Left-turn All Urban (Scottsdale)   Signal     56 14 45 6     EB Before-After
Rear-end All     Signal 52,625-109,067 12,562-33,679 45   -15 3     EB Before-After
Rear-end All     Signal 17,000-78,000   37 13 -57 1     EB Before-After
Rear-end All Urban (Scottsdale)   Signal     56   -41 11     EB Before-After
Rear-end Fatal/Injury     Signal 52,625-109,067 12,562-33,679 45   -24 12     EB Before-After
Right-angle All     Signal 52,625-109,067 12,562-33,679 45   25 3     EB Before-After
Right-angle All Urban (Scottsdale)   Signal     56 14 20       EB Before-After
Right-angle Fatal/Injury     Signal 52,625-109,067 12,562-33,679 45   16 6     EB Before-After
Install far-side bus stops Ped All           28   1        
Install flashing red/yellow signal (MUTCD: intersection control beacon) All All     No signal <5,000/lane (Total) 15   25       Simple Before-After
All All     No signal >5,000/lane (Total) 15   26       Simple Before-After
All All     No signal     15   26        
All Fatal/Injury     No signal     15   50       Simple Before-After
Head-on All     No signal     15   50       Simple Before-After
Right-angle All     No signal <5,000/lane (Total) 15   35       Simple Before-After
Right-angle All     No signal >5,000/lane (Total) 15   36       Simple Before-After
Right-angle All     No signal     15   36        
Install pedestrian crossing (signed and marked with curb ramps and extensions) All All     No signal     28   37   25 48  
Install pedestrian overpass/underpass Ped All     No signal     28   13        
Install stop signs at alternate intersections in residential areas All All Urban   Stop     53   50   45 55  
All Fatal/Injury Urban   Stop     53   67   61 72  
Vary frequency of driveways within 250 ft of intersection All All Rural   Signal     6   100(1-EXP(0.046(Nd-3))); Nd=number of driveways on the major road within 250ft of the intersection  
All All Rural   Stop     6   100(1-EXP(0.056(Nd-3))); Nd=number of driveways on the major road within 250ft of the intersection  
Vary lane width All All Urban   Signal     6   100(1-EXP(-0.053(Wl-12))); Wl=lane width (ft)  
All All Urban   Stop     6   100(1-EXP(-0.057(Wl-12))); Wl=lane width (ft)  
Vary sight distance All All Rural   Signal     6   0        
Vary through lanes All All Rural   Signal     6   100(1-EXP(0.007(Nln-2))); Nln=number of through lanes on the road  
All All Rural   Stop     6   100(1-EXP(-0.093(Nln-2))); Nln=number of through lanes on the road  
Vary truck presence All All Rural 4-leg Signal     6   100(1-EXP(0.026(Pt-9))); Pt=percent truck during the peak hour (average for all intersection movements)  
All Fatal/Injury Rural 3-leg Stop     6   100(1-EXP(-0.0253(Pt-9))); Pt=percent truck during the peak hour (average for all intersection movements)  
All Fatal/Injury Rural 4-leg Stop     6   100(1-EXP(-0.0520(Pt-9))); Pt=percent truck during the peak hour (average for all intersection movements)  
All Fatal/Injury Rural 4-leg Signal     6   100(1-EXP(0.0323(Pt-9))); Pt=percent truck during the peak hour (average for all intersection movements)  

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Page last modified on April 1, 2019
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