Desktop Reference 

 for 

 Crash Reduction Factors 

Report No. FHWA-SA-07-015 U.S. Department of Transportation Federal Highway Administration Se
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Technical Report Documentation Page 

1. Report No.: FHWA-SA-07-015 2. Government Accession No.: 3. Re4. Title and Subtitle 5. ReDesktop Reference for Crash Reduction Factors 6. Pe

iTRAN

7. Authors: Bahar, Geni; Masliah, Maurice; Wolff, Rhys; Park, Peter 8. Pe

Repo

9. Performing Organization Name and Address: 10. WiTRANS Consulting Ltd. Vanasse Hangen Brustlin, Inc 1220 L Street NW, #100-467 8300 Boone Blvd., Ste. 700 Washington, DC 2005-4018 Vienna, VA 22182-2626 (research) (editorial) 

11. CDTFH

13. TyCoveJanua

12. Sponsoring Agency Name and Address: U.S. Department of Transportation Federal Highway Administration (FHWA) Office of Safety 1200 New Jersey Avenue, SE Washington, DC 20590 14. S

FHWA

15. Supplementary Notes: FHWA Office of Safety Contract Task Order Manager Dr. Clayton Chen (clayton.che16. Abstract. This Desktop Reference documents the estimates of the crash reduction that might be expected i

or group of countermeasures is implemented with respect to intersections, roadway departure and other non-inpedestrian crashes. The estimates of crash reduction are known as Crash Reduction Factors (CRFs), and repravailable to date. Where available, the Desktop Reference includes multiple CRFs for the same countermeasureview the range of potential effectiveness. The CRFs are a useful as a guide, but it remains necessary to appl

to consider site-specific environmental, traffic volume, traffic mix, geometric, and operational conditions which wof a countermeasure. 17. Key Words: crash reduction factor, CRF, intersection crashes, pedestrian crashes, roadway departure crashes 

18. Distribution Statement: No restrictions. This document is availthe National Technical Information Se

19. Security Classification (of this report): Unclassified 20. Security Classifications (of this 

page): Unclassified 

2P

Form DOT F 1700.7 (8-72) Reproduction of completed pages author
September 2007 

Table of Contents 

Introduction..................................................................................................................................................Tables for Intersection Crash Reduction Factors

Table 1: Signalization Countermeasures ...........................................................................................Table 2: Geometric Countermeasures................................................................................................Table 3: Signs / Markings / Operational Countermeasures ...............................................................

Tables for Roadway Departure Crash Reduction Factors

Table 4: Barrier Countermeasures .....................................................................................................Table 5: Bridge Countermeasures......................................................................................................Table 6: Geometric Countermeasures................................................................................................Table 7: Median Countermeasures ....................................................................................................Table 8: Roadside Countermeasures .................................................................................................Table 9: Signs / Markings / Operational Countermeasures ...............................................................

Tables for Pedestrian Crash Reduction Factors

Table 10: Signalization Countermeasures ........................................................................................Table 11: Geometric Countermeasures..............................................................................................Table 12: Signs / Markings / Operational Countermeasures .............................................................

References.....................................................................................................................................................
September 2007 

Desktop Reference for Crash Reduction Fa

Introduction This Desktop Reference provides estimates of the crash reduction that might be expected if a specific cou

countermeasures is implemented with respect to intersection crashes, roadway departure and other non-in

pedestrian crashes. The crash reduction estimates are known as Crash Reduction Factors (CRFs). The CR

information available to date. In some cases, the CRF is expressed as a Crash Reduction Function. Where available, the Desktop Reference includes multiple CRFs for the same countermeasure to allow th

of potential effectiveness. This Desktop Reference includes CRFs for which the reliability of the estimate approach is part of the philosophy of bringing together all the information available to date. (A few CRFs not included in the Desktop Reference. These CRFs were considered to have too large a range or too large meaningful, or the original research did not provide sufficient detail for the CRF to be useful.) The CRFs may be periodically updated as new information becomes available. Crash Reduction Factors A CRF is the percentage crash reduction that might be expected after implementing a given countermeasuis negative, i.e. the implementation of a countermeasure is expected to lead to a percentage increase in craregarded as a generic estimate of the effectiveness of a countermeasure. The estimate is a useful guide, b

apply engineering judgment and to consider site-specific environmental, traffic volume, traffic mix, geomconditions which will affect the safety impact of a countermeasure. The user must ensure that a countermparticular conditions being considered. The reader is also encouraged to obtain and review the original sodetailed information, and to search databases such as the National Transportation Library (ntlsearch.bts.g

becomes available after the publication of this Reference. Traffic engineers and other transportation professionals can use the information contained in this issue br

types of question: Which countermeasures might be considered at the signalized intersection of Maple an

experiencing a high number of total crashes and left-turn crashes? What change in the number of total cr

can be expected with the implementation of the various countermeasures? 
September 2007 

In the Tables presented in the Desktop Reference, CRFs are provided in the column “Crash Reduction Faerror of the CRF is given where available in the column “Std Error.” The standard error is the standard de

estimate of the CRF. The true value of the CRF is unknown. The standard error provides a measure of the true value of the CRF. A relatively small standard error indicates that a CRF is relatively precisely knownerror indicates that a CRF is not precisely known. The standard error may be used to estimate a confidenc

the CRF. (An example of a confidence interval calculation is given below.)

As an example, the CRF for the countermeasure install cameras to detect red-light running for right-angl

The following points should be noted:  The CRF of 16 means that a 16% reduction in fatal/injury crashes is expected after the installation of  This CRF is bolded which means that a) a rigorous study methodology was used to estimate the CRF, 

relatively small. A CRF which is not bolded indicates that a less rigorous methodology (e.g. a simple to estimate the CRF, and/or the standard error is large compared with the CRF. 

 The standard error for this CRF is 6. Using the standard error, it is possible to calculate the 95% confi

potential crash reduction that might be achieved by implementing the countermeasure. The 95% conf

errors from the CRF. Therefore, the 95% confidence interval for the installation of red-light running c28% (16 - 2×6 = 4%, and 16 + 2×6 = 28%). 

 The reference number is 45 (Persaud et al., as listed in the References at the end of this Desktop Refe

Crash Reduction Functions In some cases, a CRF is given in the form of a function. As an example of a function, consider the counte

presence” at 4-leg signalized intersections on rural highways. This function is shown in Table 3. The studBonneson et al. The function for “Vary truck presence” is: 

CRF = 100

×[1-e(0.026×(Pt-9))] 

Where Pt = percent trucks during the peak hour (average for all intersection movements) 
September 2007 

The value of 9 in the function reflects the base condition: 9% trucks at 4-leg signalized intersections durinhighways (average for all intersection movements). If, for example, a practitioner wants to know the safetruck presence to 7%, then the resulting CRF value from the function would be 5 (=100

×(1-e(0.026× (7-9)))). 

that crash frequency is reduced by about 5% for a 2 percentage point decrease in truck presence (from 9% Using the Tables Twelve Tables of CRFs are provided in this Reference. The Tables are grouped under intersection, roadw

crashes, and summarize the information available. The Tables include as much information as is available The Tables for intersection CRFs contain the following information (where available) for each counterme

severity, area type, configuration, control, major road daily traffic volume (vehicles/day), minor road dail

(vehicles/day), reference, number of intersections observed, crash reduction factor/function, standard erroThe Tables for roadway departure CRFs contain the following information (where available) for each coucrash severity, area type, road type, maximum daily traffic volume (vehicles/day), minimum daily traffic reference, crash reduction factor/function, standard error, range, and study type. The Tables for pedestrian CRFs contain the following information (where available) for each countermeaseverity, area type, reference, crash reduction factor/function, standard error, range, and study type. The following points should be noted:  The crash severities are: all, fatal/injury (fatal and injury crashes combined), fatal, injury, or property  Where available, the Tables provide existing traffic control information (i.e. the conditions existing b

countermeasure). The control information for the pre-countermeasure study site may be “no signal,” “

“stop/yield.” “No signal” is used when a publication specifies that the intersection was not signalized was introduced, but does not provide details. (In these cases, the intersection could have yield or stop Where the original study is not clear, or omits to give the information, the cell is left blank. 

 Road type information (for roadway departure countermeasures) uses the following road types (where 

multilane divided, arterial, highway, or freeway. Where the original study was not clear, or omitted to 

cell is left blank or the study’s wording is used. 

 In the observed column, a higher number of intersections/sites usually corresponds with a more reliab

effectiveness. 
September 2007 

 For some countermeasures, a range of safety effectiveness is provided in the Range Low and Range H The study type refers to the methodology used in the CRF study.  A blank cell means that no information is reported in the source document.  The following abbreviations appear in the Tables: 

o App = Approaches o Avg = Average o Config = Configuration o EB = Empirical Bayes o Emerg = Emergency o Max = Maximum o Min = Minimum o Obs = Number of observed intersections o PDO = Property Damage Only o Ped = Pedestrian o Ref = Reference o ROR = Run-Off-Road o Std Error = Standard Error 

 For additional information, please visit the FHWA Office of Safety website safety.fhwa.dot.gov. 
Tables for Intersection Crash Reduction Facto
Table 1: Signalization Countermeasures
Desktop Reference for Crash Reduction Factors 

Major Minor 

All All Signal 15 15 

Rightangle All Signal 15 30 

Add all-red clearance interval (from 0 to 1 second)

Rightangle All Urban Signal 47 6 0 

Add exclusive pedestrian phasing Ped All Signal 28 34 

All All Signal 25 -15 

Left-turn All Signal 25 -49 

All All Signal 25 -20 

All Fatal/Injury Signal 25 -10 

Left-turn All Signal 25 -65 

Rear-end All Signal 25 4 

All All Signal 29 13 

Left-turn All Signal 29 33 

Daily Traffic 

Volume (veh/day)

SIGNAL OPERATIONS COUNTERMEASURES

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Add all-red clearance intervalConvert exclusive leading protected to exclusive lagging protectedConvert protected left-turn phase to protected/permissiveConvert protected/permissive left-turn phase to permissive/protected

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All 4-Leg Signal 49 8 

All All 4-Leg Signal 39 20 18All Fatal/Injury 4-Leg Signal 49 12 

Head-on Fatal/Injury Signal 15 75 

Left-turn All Signal 15 75Left-turn Fatal/Injury Signal 15 55 Left-turn PDO Signal 15 63 

Multivehicle All All Signal 21 40 5 

Multivehicle Fatal/Injury All Signal 21 40 9 

ROR Fatal/Injury Signal 15 62 ROR PDO Signal 15 28 

Olderdriver All 4-Leg Signal 39 20 42

Rear-end All 4-Leg Signal 49 -12 

Improve signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)]

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Rear-end Fatal/Injury 4-Leg Signal 49 -8 

Rear-end PDO Signal 15 17 

Rightangle All 4-Leg Signal 49 4 

Rightangle Fatal/Injury Signal 15 30 

Rightangle Fatal/Injury 4-Leg Signal 49 -6 

Rightangle PDO Signal 15 46 

Ped Fatal/Injury Signal 49 37

All All Signal 15 15 

Rightangle All Signal 15 30 

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

Increase yellow change intervalImprove signal timing [to intervals specified by the ITE Determining Vehicle Change Intervals: A Proposed Recommended Practice (1985)] (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Signal 15 20All All 15 25All All 15 15

Ped All Signal 15 53Ped All Signal 5 0Ped All 15 55Ped All 15 50

Modify signal phasing (implement a leading pedestrian interval)

Ped All Signal 28 5

Left-turn All Signal 15 80 

Rightangle All Signal 15 10 

Provide Advanced Dilemma Zone Detection for rural high speed approaches

All Fatal/Injury Rural 4-Leg (1 app) Signal 61 5 39 

All All Signal 15 30 

All All Signal 15 36 

All All Signal 15 15 

All All Signal 15 25 All All Signal 15 30 

All All Signal 15 27

Left-turn All Signal 15 41 

<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)

Provide protected leftturn phase

Install pedestrian signalProvide actuated signals

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Left-turn All Signal 15 46 

Left-turn All Signal 15 35 

Left-turn All Signal 15 70 Left-turn All Signal 15 48Left-turn Fatal/Injury Urban Signal 31 30 16 

Rightangle Fatal/Injury Urban Signal 31 30 19 

Overturn All Signal 15 27 Overturn All Signal 15 35 Overturn All Signal 15 31

Ped All Signal 28 5

Rear-end All Signal 15 27 Rear-end All Signal 15 35 Rear-end All Signal 15 31

Rightangle All Signal 15 54 

Rightangle All Signal 15 56 Rightangle All Signal 15 80 Rightangle All Signal 15 63

<5,000/lane(Total)>5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)

Provide protected leftturn phase (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Left-turn Fatal/Injury Urban Signal 31 15 16 

Rightangle Fatal/Injury Urban Signal 31 15 12 

Left-turn Fatal/Injury Urban Signal 31 20 17 

Rightangle Fatal/Injury Urban Signal 31 20 25 

All All All Signal 1 15All All Signal 28 16All All Arizona Signal 3 7

Rightangle All Signal 28 32 

Provide split phases All All Signal 28 25

All All Signal 28 29

Rightangle All Signal 47 17 75 

Rightangle All Signal 28 80

Add 3-inch yellow retroreflective sheeting to signal backplates

All All Urban Signal 54 15 

Olderdriver All 4-Leg Signal 39 33 31

Youngerdriver All 4-Leg Signal 39 33 17

Provide protected leftturn phase (leading 

green arrow)Provide signal coordination

SIGNAL HARDWARE COUNTERMEASURES

Add additional signal and upgrade to 12-inch lensesRemove flash mode (late night/early morning)Provide protected/permissive left-turn phase (leading flashing green) (Request MUTCD Experimentation)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Signal 28 10All All Urban 4-Leg Signal 14 63 28 All Fatal/Injury Urban 4-Leg Signal 14 63 17 All PDO Urban 4-Leg Signal 14 63 31 

Rear-end All Urban 4-Leg Signal 14 63 28 

Rightangle All Signal 28 42Rightangle All Urban 4-Leg Signal 14 63 35 

All All Signal 51 49All All Signal 35 6 25 

All All Signal 35 33 32 

All All Signal 28 36 All Fatal/Injury Signal 51 44All PDO Signal 51 51

Left-turn All Signal 51 12

Rear-end All Signal 51 41

Rightangle All Signal 51 74Rightangle All Signal 35 6 63 

Convert signal from pedestal-mounted to mast armAdd signal (additional primary head)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Urban Signal 52 224 7 All Fatal/Injury Urban Signal 52 224 3 All PDO Urban Signal 52 224 9 

Day All Urban Signal 52 224 6 

Night All Urban Signal 52 224 6 

All All Signal 28 9

Rightangle All Signal 28 36

All All All Signal 1 10All All Signal 28 11All All Signal 15 10All All Signal 15 10 All All Signal 28 11 All All Urban Signal 54 24 All Fatal/Injury Urban Signal 54 16 

Rightangle All Signal 47 44 46 Rightangle All Signal 28 48

All All Signal 28 13 

Rightangle All Signal 28 50 Rightangle All Signal 15 20Rightangle All Signal 15 20 

Install larger signal lenses (12 inch)Improve visibility of signal heads (increase signal lens size, install new backboards, add reflective tape to existing backboards, and/or install additional signal heads)Improve visibility of signal heads (install two red displays in each head)Install signal backplates onlyInstall signal backplates (or visors)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All No signal 15 38 All All No signal 15 20 All All No signal 28 33 

Left-turn All No signal 43 447 38 

Right-turn All No signal 43 447 50 

All All Rural No signal 43 447 15 

All Fatal No signal 43 447 38 

Rear-end All No signal 43 447 -48 

Rightangle All No signal 43 447 29 

All All Urban No signal 43 447 17 

All All No signal 15 22All All No signal 15 15 

All All No signal 15 13 All All No signal 15 20 All All No signal 15 25 All All No signal 15 20 All Fatal/Injury Urban 3-Leg Stop 11,750- 42,000 900- 4,000 34 14 All Fatal/Injury Urban 4-Leg Stop 12,650- 22,400 2,400- 3,625 34 23 

Overturn All No signal 15 22 Overturn All No signal 15 20 

Rear-end All No signal 15 22 Rear-end All No signal 15 20 

>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)

Install signals

<5,000/lane(Total)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Rear-end Fatal/Injury Urban 3-Leg Stop 11,750- 42,000 900- 4,000 34 -50 Rear-end Fatal/Injury Urban 4-Leg Stop 12,650- 22,400 2,400- 3,625 34 -38 

Rightangle All No signal 15 74 Rightangle All No signal 15 43 Rightangle All No signal 15 58Rightangle All No signal 15 60 Rightangle All No signal 15 42 Rightangle All No signal 15 65 Rightangle All No signal 15 65 Rightangle All No signal 28 68Rightangle All No signal 47 8 74 Rightangle Fatal/Injury Urban 3-Leg Stop 11,750- 42,000 900- 4,000 34 34 Rightangle Fatal/Injury Urban 4-Leg Stop 12,650- 22,400 2,400- 3,625 34 67 

All PDO No signal 43 447 -15 

Head-on PDO No signal 15 83 

Left-turn PDO No signal 15 11 

Rightangle Fatal/Injury No signal 15 39 

>5,000/lane(Total)<5,000/lane(Total)

Install signals (temporary)Install signals (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Rightangle PDO No signal 15 73 

Sideswipe Fatal/Injury No signal 15 50 

Install signals (to have one over each approach lane)

Rightangle All All 35 46 

All All Signal 15 75All All Signal 15 100 

All All Signal 15 50 All All Signal 15 75 

All All Signal 28 52 All All Urban Signal 21 199 24 All Fatal/Injury Urban Signal 21 199 53 All PDO Urban Signal 21 199 24 

Day All Urban Signal 21 199 22 

Fixedobject All Urban Signal 21 199 31 

Night All Urban Signal 21 199 30 

Rear-end All Signal 15 95 Rear-end All Signal 15 100 Rear-end All Signal 15 90 Rear-end All Urban Signal 21 199 29 

Rightangle All Urban Signal 21 199 24 

Install signals (temporary) (cont'd)Remove unwarranted signals

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Signal 28 17 All All Signal 15 15All All Signal 15 15 

Head-on All Signal 15 20 

Left-turn All Signal 15 10 

Rear-end All Signal 15 10 

Rightangle All Signal 15 10 

Install left-turn lane and add turn phase All All Signal 28 58 

Head-on PDO No signal 15 27 

Left-turn PDO No signal 15 24 

ROR Fatal/Injury No signal 15 35 

Rightangle Fatal/Injury No signal 15 67 

Rightangle PDO No signal 15 63 

Sideswipe Fatal/Injury No signal 15 54 

Install signals and add channelizationReplace signal lenses with optical lenses

COMBINATION SIGNAL AND OTHER COUNTERMEASURES

FHWA-SA-07-015 September 2007 
Table 2: Geometric Countermeasures
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Stop >34,000 59 18 All All Stop >34,000 4 lanes 59 -24 

All All Stop >34,000 6 lanes 59 26 

All All Stop >34,000 8 lanes 59 24 

All Fatal/Injury Stop >34,000 59 27 All PDO Stop >34,000 59 6 

Create directional median openings to allow left-turns and u-turns

All All Signal 51 51All All All 1 25All All Rural 3-Leg Signal 4,200- 26,000 1,300- 11,400 22 199 15 All All Rural 3-Leg Stop 1,100- 32,400 25- 11,800 22 44 All All Rural 4-Leg (1 app) Signal 4,200- 26,000 1,300- 11,400 22 199 18 All All Rural 4-Leg (1 app) Stop 1,100- 32,400 25- 11,800 22 28 All All Rural 4-Leg (2 app) Stop 1,100- 32,400 25- 11,800 22 48 All All No signal 15 34All All No signal 15 35 

All All No signal 15 35 All All No signal 15 25 

Add indirect left-turn treatments to minimize conflictsInstall left-turn lane 

LEFT-TURN COUNTERMEASURES

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All No signal 15 40 

All All No signal 28 33 All All Urban 3-Leg Signal 4,600- 55,100 100- 26,000 22 199 7 All All Urban 3-Leg Stop 1,520- 40,600 80-8,000 22 33 

All All Urban 4-Leg (1 app) Signal 4,600- 55,100 100- 26,000 22 10 

All All Urban 4-Leg (1 app) Stop 1,520- 40,600 80-8,000 22 27 

All All Urban 4-Leg (2 app) Signal 4,600- 55,100 100- 26,000 22 19 All All Urban 4-Leg (2 app) Stop 1,520- 40,600 80-8,000 22 47 All Fatal/Injury Rural 3-Leg Stop 1,100- 32,400 25- 11,800 22 55 All Fatal/Injury Rural 4-Leg (1 app) Stop 1,100- 32,400 25- 11,800 22 35 All Fatal/Injury Rural 4-Leg (2 app) Stop 1,100- 32,400 25- 11,800 22 58 All Fatal/Injury Urban 4-Leg (1 app) Signal 4,600- 55,100 100- 26,000 22 9 

All Fatal/Injury Urban 4-Leg (1 app) Stop 1,520- 40,600 80-8,000 22 29 All Fatal/Injury Urban 4-Leg (2 app) Signal 4,600- 55,100 100- 26,000 22 17 All Fatal/Injury Urban 4-Leg (2 app) Stop 1,520- 40,600 80-8,000 22 50 

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 Left-turn All Rural 4-Leg (1 app) Stop 1,100- 32,400 25- 11,800 21 23 37 

Install left-turn lane (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Left-turn All Rural 4-Leg (2 app) Stop 1,100- 32,400 25- 11,800 21 23 60 

Left-turn All No signal 15 55Left-turn All No signal 15 55 

Left-turn All No signal 28 68 Left-turn All Signal 15 24 

Left-turn All Urban 4-Leg (1 app) Signal 4,600- 55,100 100- 26,000 21 35 13 

Left-turn All Urban 4-Leg (1 app) Stop 1,520- 40,600 80-8,000 21 7 26 

Left-turn All Urban 4-Leg (2 app) Signal 4,600- 55,100 100- 26,000 21 35 24 

Left-turn All Urban 4-Leg (2 app) Stop 1,520- 40,600 80-8,000 21 7 45 

Night All Signal 15 28 

Overturn All Signal 15 28 

Head-on Fatal/Injury 15 75 

Left-turn Fatal/Injury 15 47 

Left-turn PDO 15 71 

ROR Fatal/Injury 15 8 ROR PDO 15 13 

Rear-end Fatal/Injury 15 29 Rear-end PDO 15 32 

>5,000/lane(Total)>5,000/lane(Total)>5,000/lane(Total)

Install left-turn lane (cont'd)Install left-turn lane (double)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Rightangle Fatal/Injury 15 20 

Rightangle PDO 15 8 

Sideswipe Fatal/Injury 15 50 

All All 15 50 

All Fatal/Injury Rural 3-Leg 5,000- 15,000 13 22 All Fatal/Injury Rural 4-Leg 5,000- 15,000 13 -28 All PDO Rural 3-Leg 5,000- 15,000 13 20 All PDO Rural 4-Leg 5,000- 15,000 13 26 

Left-turn All 15 57 

Left-turn All 15 35 

Overturn All 15 54 Overturn All 15 39 

Rear-end All 15 54 Rear-end All 15 39 

Rightangle All 15 62 Rightangle All 15 49 

All All All No signal 1 35All All All Signal 1 25All All Rural 3-Leg No signal 28 44

<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)

Install left-turn lane (double) (cont'd)Install left-turn lane (painted separation)Install left-turn lane (physical channelization)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Rural 4-Leg (1 app) No signal 28 28

All All 4-Leg (2 app) No signal 28 42

All All 15 51 

All All 15 19 

All All Urban 3-Leg No signal 28 33All All Urban 4-Leg (1 app) No signal 28 27

All Fatal/Injury Rural 3-Leg 5,000- 15,000 13 27 

All Fatal/Injury Rural 4-Leg 5,000- 15,000 13 4 All PDO Rural 3-Leg 5,000- 15,000 13 -20 All PDO Rural 4-Leg 5,000- 15,000 13 16 

Left-turn All 15 24 

Left-turn All 15 24 

Left-turn Fatal/Injury 15 50 

ROR PDO 15 50 

Overturn All 15 50 Overturn All 15 28 

Rear-end All 15 50 Rear-end All 15 28 

<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)

Install left-turn lane (physical channelization) (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Rear-end Fatal/Injury 15 11 Rear-end PDO 15 56 

Rightangle All 15 68 Rightangle All 15 55 Rightangle Fatal/Injury 15 58 

Rightangle PDO 15 54 

All All Signal 28 31 All All Signal 51 35

Left-turn All Signal 28 44 

Olderdriver 

head-on

All 4-Leg Signal 39 13 73

Youngerdriver 

head-on

All 4-Leg Signal 39 13 66

All All Signal 28 23 

Left-turn All Signal 28 50 

All All Signal 15 35All All Signal 15 35 

All All Signal 15 35 All All 15 15All All 15 15 

All All 15 15 

<5,000/lane(Total)>5,000/lane(Total)

Install left-turn lane (signal has left-turn phase)Install left-turn lane (physical channelization) (cont'd)Install left-turn lane (signal has no turn phase)Install left-turn lane (with channelization and existing left-turn phase)Install left-turn lane (with channelization and no left-turn phase)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Signal 28 26

Left-turn All Signal 28 66

All All 15 24 

All All 15 44 

Head-on All 15 52 

Left-turn All 15 77 

Overturn All 15 44 Overturn All 15 40 

Rear-end All 15 44 Rear-end All 15 40 

Sideswipe All 15 52 

All All Rural 3-Leg Signal 6 -18All All Rural 4-Leg (1 app) Signal 6 -22All All Rural 4-Leg (2 app) Signal 6 -49All All Urban 3-Leg Signal 6 -8All All Urban 3-Leg Stop 6 -49All All Urban 4-Leg (1 app) Signal 6 -11All All Urban 4-Leg (1 app) Stop 6 -37All All Urban 4-Leg (2 app) Signal 6 -23

<5,000/lane(Total)>5,000/lane(Total)>5,000/lane(Total)>5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)

Install left-turn refuge within flush medianRemove left-turn laneInstall left-turn lane (within existing curbs)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Urban 4-Leg (2 app) Stop 6 -88All Fatal/Injury Rural 3-Leg Signal 6 -16All Fatal/Injury Rural 4-Leg (1 app) Signal 6 -21All Fatal/Injury Rural 4-Leg (2 app) Signal 6 -45All Fatal/Injury Urban 3-Leg Signal 6 -6All Fatal/Injury Urban 3-Leg Stop 6 -53All Fatal/Injury Urban 4-Leg (1 app) Signal 6 -10All Fatal/Injury Urban 4-Leg (1 app) Stop 6 -41All Fatal/Injury Urban 4-Leg (2 app) Signal 6 -21All Fatal/Injury Urban 4-Leg (2 app) Stop 6 -98

Increase length of right-turn lane All Fatal/Injury All All All 58 15

All All All 4-Leg (1 app) Signal 4,200- 55,100 100- 26,000 22 4 

All All All 4-Leg (1 app) Stop 1,100- 40,600 25- 11,800 22 14 All All All 4-Leg (2 app) Signal 4,200- 55,100 100- 26,000 22 8 All All All 4-Leg (2 app) Stop 1,100- 40,600 25- 11,800 22 26 All All All All All 58 35All All All 1 25All All Rural 4-Leg (1 app) No signal 28 14

All All Rural 4-Leg (1 app) No signal 28 21 

RIGHT-TURN COUNTERMEASURES

Install right-turn laneRemove left-turn lane (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All All No signal 28 27 All All 15 25All All 15 25 All All 15 25 

All All 15 25 

All Fatal/Injury All 4-Leg (1 app) Signal 4,200- 55,100 100- 26,000 22 9 

All Fatal/Injury All 4-Leg (1 app) Stop 1,100- 40,600 25- 11,800 22 23 All Fatal/Injury All All No signal 58 35All Fatal/Injury All All Signal 58 35All Fatal/Injury All All 51 40All Fatal/Injury Rural All All 58 35All Fatal/Injury Urban All All 58 30

Rear-end All 15 65 

Rightangle All 15 50 

Right-turn All 15 53Right-turn All 15 56 Right-turn All 15 50 

Sideswipe All 15 20 

Install right-turn lane (painted separation) All Fatal/Injury All All All 58 30Install right-turn lane (physical channelization)

All Fatal/Injury All All All 58 35

Install right-turn lane (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All 4-Leg No signal 28 57All Fatal/Injury Urban 4-Leg <70% >30% 13 33 

All Fatal/Injury Urban 4-Leg >85% <15% 13 -35 

All Fatal/Injury Urban 4-Leg 70-85% 15-30% 13 25 

All PDO Urban 4-Leg <70% >30% 13 10 

All PDO Urban 4-Leg >85% <15% 13 -15 All PDO Urban 4-Leg 70-85% 15-30% 13 0 All All 4-Leg 51 57 All All All All 50 55 35 

All All All Signal 50 9 48 All All All Signal 21 23 40 All All All Stop (2-way) 50 36 44 All All All Stop (4-way) 50 10 -3 All All Rural 1-lane Stop (2-way) 50 9 72 All All Rural Stop 7,185- 17,220 44 58 All All 3-Leg 15 50 

All All 4-Leg 15 75 

* Percentage of Total Daily Traffic VolumeConvert intersection to roundabout

OTHER GEOMETRIC COUNTERMEASURES

Convert four-leg to two T-intersections

**

*

**

* *

**

*

**

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All Fatal/Injury 55 181 65 

All PDO 55 181 42 

Ped All 55 181 89 

All All Urban Stop 13,272- 30,418 44 5 All All Urban Signal 5,322- 31,525 44 35 All All Urban Signal 50 5 1 All All Urban Signal 21 4 35 All All Urban Stop (2-way) 50 27 31 All All Urban 1-lane Stop (2-way) 50 16 56 All All Urban 2-lane Signal 50 4 67 All All Urban 2-lane Stop (2-way) 50 11 18 All All Urban Stop 4,600- 17,825 44 72 All Fatal/Injury All All 50 55 76 All Fatal/Injury All Signal 50 9 78 All Fatal/Injury All Stop (2-way) 50 36 82 

Convert intersection to roundabout (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All Fatal/Injury All Stop (4-way) 50 10 -28 

All Fatal/Injury All All 21 23 80 All Fatal/Injury Rural 1-lane Stop (2-way) 50 9 87 All Fatal/Injury Rural Stop 7,185- 17,220 44 82 All Fatal/Injury No signal 11 62 44 

All Fatal/Injury Signal 11 34 32 

All Fatal/Injury 11 96 39 

All Fatal/Injury Urban Signal 50 5 60 All Fatal/Injury Urban Stop (2-way) 50 27 74 

All Fatal/Injury Urban 1-lane Stop (2-way) 50 16 78 All Fatal/Injury Urban 2-lane Stop (2-way) 50 11 72 All Fatal/Injury Urban Signal 5,322- 31,525 44 74 

All Fatal/Injury Urban Stop 4,600- 17,825 44 88 

Ped Fatal/Injury No signal 11 27Ped Fatal/Injury Signal 11 -28

Convert intersection to roundabout (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Rural 3-Leg Stop 6All All Rural 4-Leg Stop 6

Improve sight distance in 1 quadrant

All All Rural 4-Leg Stop/Yield (2-way) 23 5 

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

All All Rural 4-Leg Signal 23 0All All Rural 4-Leg Stop/Yield (2-way) 23 17All Fatal 51 56All Injury 51 37

Multiplevehicle All Rural 4-Leg Stop 24 4 

Multiplevehicle All Urban 3-Leg Stop 24 -3 

Multiplevehicle All Urban 4-Leg Signal 24 -3 

Multiplevehicle All Urban 4-Leg Stop 24 -6 

Multiplevehicle Fatal/Injury Rural 4-Leg Stop 24 4 Multiplevehicle Fatal/Injury Urban 4-Leg Signal 24 -3 Multiplevehicle Fatal/Injury Urban 4-Leg Stop 24 -5 

Increase median width by 3 ft

100(1-EXP(0.0048*|angle - 90o|)); angle 100(1-EXP(0.0054*|angle - 90o|)); angle 

Improve sight distance to intersectionImprove sight distance in 4 quadrantsImprove intersection alignment (reduce skew)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Increase pedestrian storage area at corner

All Fatal/Injury 5 -12 1

Install median All All Rural Stop 6 27Install 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 25All All No signal 28 25All All 28 25

Ped All No signal 28 69

Install raised median (marked crosswalk) Ped All 60 46Install raised median (unmarked crosswalk)

Ped All 60 39

Install refuge islands Ped All 28 56

All Fatal/Injury All 3-Leg All 58 45All Fatal/Injury All 4-Leg All 58 40All Fatal/Injury All All All 58 40All Fatal/Injury Rural All All 58 35All Fatal/Injury Urban All All 58 40All All Rural Stop 48 5 

Head-on PDO 3-Leg 15 13 

Left-turn Injury 3-Leg 15 36 Left-turn PDO 3-Leg 15 28 

Install raised medianInstall turn and bypass lanesInstall splitter islands on minor road approaches

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

ROR PDO 3-Leg 15 40 

Rear-end Injury 3-Leg 15 18 Rear-end PDO 3-Leg 15 21 

Rightangle Injury 3-Leg 15 24 

Rightangle PDO 3-Leg 15 53 

Sideswipe PDO 3-Leg 15 30 

All All Rural Stop 6All All Urban 3-Leg Stop 6All All Urban 4-Leg Stop 6All Fatal/Injury Urban 3-Leg Stop 6All Fatal/Injury Urban 4-Leg Stop 6All All Rural

3-Leg 

and 4-

Leg

Stop 6

All All Urban Stop 6

Install turn and bypass lanes (cont'd)

100(1-EXP(-0.012(WWm=median width (f100(1-EXP(0.0082(WWm>161.0 for Wm<=16; Wm(ft)

Vary median width

100(1-EXP(0.0173(WWm>161.0 for Wm<=16; Wm(ft)100(1-EXP(0.0076(WWm>161.0 for Wm<=16; Wm(ft)100(1-EXP(0.016(WWm>161.0 for Wm<=16; Wm(ft)

Vary shoulder width

100(1-EXP(-0.03(WsWs=outside shoulde100(1-EXP(-0.02(WsWs=outside shoulde

FHWA-SA-07-015 September 2007 
Table 3: Signs / Markings / Operational Counterme
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All No signal 28 11

Rightangle All No signal 47 10 55 

Rightangle All No signal 28 36

All All 3-Leg 15 70 

All All 4-Leg 15 39 

All All Signal 28 27 All All 15 25All All 15 25 All All 15 27 

All All 15 25 

Left-turn Fatal/Injury 15 67 

Left-turn PDO 15 79 

Rear-end All 4-Leg Signal 39 36

Rightangle All 4-Leg Signal 39 62Rightangle Fatal/Injury 15 73 

Rightangle Fatal/Injury 15 73 

Rightangle PDO 15 62 

Install larger stop signs All All Stop 15 19 

All All 15 4

Ped All 15 15

>5,000/lane(Total)

Install double stop signsInstall flashing beacons as advance warningInstall pedestrian signing

SIGNS

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All All 1 35All All Signal 28 22 All All Urban 15 30 All All Rural 15 40

Rightangle All Signal 47 11 35 

Rightangle All Signal 28 35

Rear-end All 51 10

Sidewipe All 51 20

All All No signal 28 29

Rightangle All No signal 28 24

All All No signal 28 9

Rightangle All No signal 28 0Rightangle All No signal 47 67 Rightangle All No signal 28 67

All All 28 25

Wet All 28 59 

All All 15 25

Ped All 15 25Ped All 15 25Ped All 15 25Ped Fatal/Injury Rural 38 60 

All All 5 30 All Fatal/Injury 5 36 

Ped All 28 8

Add centerline and move STOP bar to extended curb linesInstall advance warning signs (positive guidance)Add centerline and move STOP bar to extended curb lines, double stop signsProvide overhead lane-use signsImprove/install pedestrian crossingInstall pedestrian crossingImprove pavement friction (groove)Install pedestrian crossing (raised)Add centerline and STOP bar, replace 24-inch with 30-inch stop signs

PAVEMENT MARKINGS/MODIFICATIONS

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All Fatal/Injury 4-Leg 13 -5 All PDO 4-Leg 13 -13 All All 28 10 

Wet All 28 25 

Wet/Night All 28 33 

Install STOP bars (pedestrian crosswalk)

All All Signal 28 18 All All 28 19 

Rightangle All 28 47

All All 15 18 

Speedrelated Fatal/Injury Stop 18 57 Speedrelated Serious injury Stop 18 74 Speedrelated Slight injury Stop 18 52 

Speedrelated 

and day

All Stop 18 66 

Speedrelated 

and dry

All Stop 18 45 

Speedrelated All Stop 18 48 

Speedrelated 

and wet

All Stop 18 68 

Install raised pavement markersInstall STOP bars (STOP bar on minor road approaches, with short segments of centerline)Install transverse pavement markingsInstall raised intersection

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Rural No signal 28 35All All Stop 15 28 

All All 28 23 

Rear-end All 15 90 

All All No signal 28 6

Rightangle All No signal 28 30Rightangle All Urban Stop 47 5 30 

Provide bicycle box (advance stop bar to leave dedicated space for cyclists)

Bicycle All Signal 51 35

Provide bike lanes Bicycle All 51 36

All All 28 33 

Wet All 28 47 

All All All Stop 21 141 -137

All All Urban 4-Leg Stop 33 -127 All All All Stop 21 360 47All All No signal 28 64 All All Stop 15 53All Fatal/Injury Urban Stop 30 71 

Left-turn All Urban Stop 30 20 

Convert to all-way STOP control (from 2-

way control)

REGULATORY

Install transverse rumble strips on approachesResurface pavementMark pavement with supplementary warning messagesConvert STOP control to Yield control

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Left-turn All Stop 15 20 

Ped All 15 39Ped All Urban Stop 30 39 

Rear-end All Urban Stop 30 13 Rear-end All Stop 15 13 

Rightangle All Urban Stop 30 72 Rightangle All No signal 28 84Rightangle All Stop 15 72 Rightangle All Urban Stop 47 10 80 

All All 15 26All All 15 26 

Convert to all-way STOP control (from 2-

way control) (cont'd)Convert two-way to one-way roadway

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All No signal 28 29

Rightangle All No signal 28 9

All All Urban 7 62 

Left-turn 

(or u-turn) All Urban 7 59 

All All Signal 5 -7 

All All Signal 10 -5 

Ped All New Orleans Signal 5 -81 

Ped All New York Signal 5 -43 Ped All Ohio Signal 5 -57 Ped All Wisconsin Signal 5 -108 

Right-turn Fatal/Injury Signal 13 -60 Right-turn PDO Signal 13 -10 

All All 15 45All All 15 45 

Left-turn All 15 90 

Ped All 15 10

Rear-end All 15 30 

All All Signal 28 23 

ROR All Signal 15 30 

Rear-end All Signal 15 20 

19,435-

42,000(Total)

19,435-

42,000(Total)

Prohibit right-turn-onredProhibit left-turnsPermit right-turn-onredInstall no left-turn and no u-turn signsConvert Yield control to STOP control

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Rightangle All Signal 15 30 

Sideswipe All Signal 15 20 

Prohibit turns All turns All All 1 45 

All All 28 49 

Ped All 15 30

All All Rural 6All All Urban 6

Ped Fatal 5 78 Ped Injury 5 42 

All All Signal 51 30All Fatal/Injury Signal 51 17

Night All Signal 51 50

All All No Signal 28 47All All Stop 15 28 All Injury Stop 15 43 

Rightangle All Stop 15 74 

All All Stop 15 36 All Injury Stop 15 53 

Rear-end All Stop 15 8 

Rightangle All Stop 15 74 

Restrict parking near intersections (to offstreet)Improve lighting at intersectionProhibit right-turn-onred (cont'd)Convert STOP control (2-way) to signal controlVary speedConvert STOP control (2-way) to signal control and install left-turn laneInstall lighting

100(1-EXP(0.005(V-road speed limit (or d(mph)100(1-EXP(0.019(V-road speed limit (or d(mph)

LIGHTING

OPERATIONAL

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Increase enforcement to reduce speed

Ped All 28 70

Install angled median crosswalk All All 28 12

All All All 1 30 All All All 1 30All All Signal 28 34 All All 15 30All All 15 30 All All 15 4 

All All 15 30 All All Signal 17,000- 78,000 37 46 -12 All All Urban (Scottsdale) Signal 56 11 

All Fatal/Injury All All Signal 58 5All Fatal/Injury Signal 17,000- 78,000 37 46 -14 

Left-turn All Urban (Scottsdale) Signal 56 14 45 

Rear-end All Signal 52,625- 109,067 12,562- 33,679 45 -15 Rear-end All Signal 17,000- 78,000 37 13 -57 Rear-end All Urban (Scottsdale) Signal 56 -41 Rear-end Fatal/Injury Signal 52,625- 109,067 12,562- 33,679 45 -24 

Rightangle All Signal 52,625- 109,067 12,562- 33,679 45 25 Rightangle All Urban (Scottsdale) Signal 56 14 20 

Rightangle Fatal/Injury Signal 52,625- 109,067 12,562- 33,679 45 16 

Install cameras to detect red-light runningInstall beacon (flashing) at intersection

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

Install far-side bus stops Ped All 28 1

All All No signal 15 25 

All All No signal 15 26 All All No signal 15 26All Fatal/Injury No signal 15 50 

Head-on All No signal 15 50 

Rightangle All No signal 15 35 

Rightangle All No signal 15 36 Rightangle All No signal 15 36

Install pedestrian crossing (signed and marked with curb ramps and extensions)

All All No signal 28 37 

Install pedestrian overpass/underpass Ped All No signal 28 13

All All Urban Stop 53 50 All Fatal/Injury Urban Stop 53 67 All All Rural Signal 6All All Rural Stop 6

<5,000/lane(Total)>5,000/lane(Total)<5,000/lane(Total)>5,000/lane(Total)

Vary frequency of driveways within 250 ft of intersectionInstall stop signs at alternate intersections in residential areasInstall flashing red/yellow signal (MUTCD: intersection control beacon)

100(1-EXP(0.046(NdNd=number of drivewmajor road within 25intersection100(1-EXP(0.056(NdNd=number of drivewmajor road within 25intersection

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Major Minor 

Daily Traffic 

Volume (veh/day)

Ref Obs 

Effective

Crash Reduction 

Factor / Function

Area Type Control Crash Severity Crash Type Countermeasure(s) Config S

E

All All Urban Signal 6All All Urban Stop 6

Vary sight distance All All Rural Signal 6 0

All All Rural Signal 6All All Rural Stop 6All All Rural 4-Leg Signal 6All Fatal/Injury Rural 3-Leg Stop 6All Fatal/Injury Rural 4-Leg Stop 6All Fatal/Injury Rural 4-Leg Signal 6

Vary truck presenceVary through lanesVary lane width

100(1-EXP(-0.053(Wwidth (ft)100(1-EXP(-0.057(Wwidth (ft)100(1-EXP(-0.0520(Pt=percent truck durhour (average for all movements)100(1-EXP(0.0323(PPt=percent truck durhour (average for all movements)100(1-EXP(0.007(NlNln=number of throuroad100(1-EXP(-0.093(NNln=number of throuroad100(1-EXP(0.026(Pttruck during the peak for all intersection m100(1-EXP(-0.0253(Pt=percent truck durhour (average for all movements)

FHWA-SA-07-015 September 2007 
Tables for Roadway Departure Crash Reduction F
Table 4: Barrier Countermeasures
Desktop Reference for Crash Reduction Factors Roa

All All <5,000/lane 15 18All All >5,000/lane 15 9All All All All 1 5All All 15 5All All 15 6All All 15 7All All 15 7All All 15 11All All 15 15All All 15 15All All 15 20All Fatal All All 1 50All Injury 15 35All Injury All All 1 35

Fixed 

object All <5,000/lane 15 23

Fixed 

object All >5,000/lane 15 18

Fixed 

object All 15 21

ROR All 15 26ROR All >5,000/lane 15 32ROR All 15 28

Overturn All <5,000/lane 15 41Overturn All >5,000/lane 15 27Overturn All 15 34

Rear-end All <5,000/lane 15 41Rear-end All >5,000/lane 15 27Rear-end All 15 34

Daily Traffic 

Volume 

(veh/day)

Road Type 

Improve guardrail

BARRIER COUNTERMEASURES

Crash 

Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Animal All 15 80Animal All All All 1 90Animal All 15 70Animal All 15 90Animal Injury 15 91Animal PDO 15 61Animal 

head-on All 15 85

All All 15 14All Injury 15 31

Fixed 

object All 15 100

All Fatal 15 65All Injury 15 51All All 15 27All All 15 24All All 15 30

Install guardrail (at ditch) All Injury 15 26

All Injury 15 42

ROR All All 5 7 31 

ROR Fatal All 5 44 10 

ROR Injury All 5 47 5 

All 15 63 Fatal/ Injury

15 39

All 15 28 Fatal/ Injury

All Fatal/ Injury

Install animal fencingInstall guardrail (as shield for trees)Install guardrail (as shield for rocks and posts)Install guardrail (at culvert)Install guardrail (at embankment)Install guardrail (inside curves)Install barrier (concrete) inside and outside curveInstall guardrail (outside curves)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All 15 29All All All All 1 5All All 15 5All All 15 20All All 15 20All All 15 35All All 15 41All All 15 50All Fatal All All 1 75All Fatal 15 75All Fatal 15 83All Fatal 15 90All Injury All All 1 50All Injury 15 50

Fixed 

object Fatal All All 5 69 28 

Fixed 

object Injury All All 5 69 10 

Fixed 

object PDO 5 46 30 

ROR All 15 45ROR Fatal All 5 41 31 

ROR Injury All 5 32 10 

Install impact attenuatorsReplace guardrail with a softer material (concrete

→steel

→wire)

FHWA-SA-07-015 September 2007 
Table 5: Bridge Countermeasures
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Install bridge lighting All All 15 59

All All 15 43All All 15 39All All 15 40All All 15 50All All <5,000/lane 15 22All All >5,000/lane 15 20All All 15 11All All 15 24All All 15 24All All 15 44All Fatal 15 90All Injury 15 45

Overturn All <5,000/lane 15 41Overturn All >5,000/lane 15 32

Rear-end All <5,000/lane 15 37Rear-end All >5,000/lane 15 32

Wet All 15 50

All All 15 14All All 15 13All All 15 15

Replace bridge (general) All All All All 1 45Replace bridge (2-lane) All All 15 45Upgrade bridge parapet All All 15 5

All All 15 20All All All All 1 5All Fatal 15 76All Fatal 15 60All Fatal 15 92

Install guardrail (at bridge)Repair bridge deckInstall delineators (on bridges)

BRIDGE COUNTERMEASURES

Upgrade bridge railing

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All Injury 15 61All Injury All All 1 30All Injury 15 30All Injury 15 92All PDO 15 50

Vary bridge width All All Rural Rural Highway

6

Vary horizontal bridge radius All All Urban Urban Street 6

All All 15 45All All All All 1 45All All 15 36All All 15 40All All 15 45All All 15 47All All 15 48All All 15 55All PDO 15 95

Fixed 

object All 15 45

Fixed 

object All 15 40

15 92

Widen bridge

All Fatal/ Injury

Upgrade bridge railing (cont'd)

100(1-(EXP(-0.135Ibr(Wb-12)Ibr=presence of bridges (1 if obridges present, 0 if not), Wb=approach traveled-way width (Ps=proportion of crash type svalues of Ps, refer to source).100(1-(2.30(EXP(-2298/R)+34road)+0.781(EXP(320.9/R)Poroad=proportion of crashes throadway.

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Fixed 

object All 15 50

Head-on All 15 45Head-on All 15 40Head-on All 15 50

ROR All 15 44

Sideswipe All 15 49Sideswipe All 15 40Sideswipe All 15 50Sideswipe All 15 57

Widen bridge (18 to 24 ft) All All 15 68Widen bridge (18 to 30 ft) All All 15 93Widen bridge (20 to 24 ft) All All 15 56Widen bridge (20 to 30 ft) All All 15 90Widen bridge (22 to 24 ft) All All 15 36Widen bridge (22 to 30 ft) All All 15 86Widen bridge (cont'd)

FHWA-SA-07-015 September 2007 
Table 6: Geometric Countermeasures
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Change shoulder type and/or width All All Rural 21 

All All All All 27 20 19 

All Fatal/ Injury All All 27 51 19 

All Fatal/ Injury Rural 2-lane 38 50

All All 15 39All All All All 1 40All All 15 35All All Rural 21 All Fatal 15 87All Injury 15 87All PDO 15 87

Fixed 

object All <5,000/lane 15 68

100(1-((AMFWRA x AMFTRA1.0)PRA+1.0)), AMFWRA=acmodification factor for related based on shoulder width (for vAMfWRA, refer to source), AMFTRA=accident modificatiorelated accidents based on sh(for values of AMFTRA, refer PRA=proportion of total crashby related crashes. 

GEOMETRIC COUNTERMEASURES

Flatten horizontal curveFlatten crest vertical curve

100(1-((1.55Lc+80.2/R-0.012ILc=length of horizontal curve spirial curve length, R=curve rIs=presence of a spiral transita spiral transition is present, 0 

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Fixed 

object All >5,000/lane 15 87

Head-on All <5,000/lane 15 67Head-on All >5,000/lane 15 64

ROR All <5,000/lane 15 90ROR All >5,000/lane 15 79

Overturn All <5,000/lane 15 73Overturn All >5,000/lane 15 24

Rear-end All <5,000/lane 15 73Rear-end All >5,000/lane 15 24Rear-end All 15 49

Flatten horizontal curves (10 to 5 degrees) All All 15 45Flatten horizontal curves (15 to 5 degrees) All All 15 63Flatten horizontal curves (20 to 10 degrees) All All 15 48

All All <5,000/lane 15 43All All >5,000/lane 15 45All All All All 1 30All All 15 25All All 15 30All All 15 32All All 15 35

Fixed 

object All 15 62

ROR All 15 10

Flatten horizontal curve (cont'd)Flatten side slopes

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All 15 8

Ped All 15 14

Right-turn All 15 14

All All 15 7All Injury Rural 2-lane 5 22

4 

All PDO Rural 2-lane 5 24

2 

Ped All 15 12

Right-turn All 15 12

All All Rural 2-lane 15 11

ROR All Rural 2-lane 5 24 21 

Ped All Rural 2-lane 15 19

Right-turn All 15 19

All All 15 8

Ped All 15 14

Right-turn All 15 14

All All 15 5All Injury Rural 2-lane 5 42

4 

All PDO Rural 2-lane 5 29

4 

ROR All Rural 2-lane 5 18 16 

Ped All 15 8

Right-turn All 15 8

All All 15 12

Ped All 15 21

Right-turn All 15 21

All All 15 9

Ped All 15 15

Right-turn All 15 15

Flatten side slopes (27 to 11 degrees)Flatten side slopes (18 to 14 degrees)Flatten side slopes (27 to 9 degrees)Flatten side slopes (18 to 9 degrees)Flatten side slopes (18 to 11 degrees)Flatten side slopes (11 to 8 degrees)Flatten side slopes (14 to 9 degrees)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All 15 6

Ped All 15 10

Right-turn All 15 10

Flatten side slopes and remove guardrail All All All All 27 42 58 

All All Rural All 21 0 All All Rural 21 All All Rural 21 All All 15 25All All All All 1 25All All 15 58All All All All 1 50All All 15 50All All 15 50All All 15 73All All 15 49All All All All 1 40All All 15 40All All 15 57All PDO 15 83All All 15 40All All 1 40

ROR All 15 50

All All 15 45All All 15 40All All 15 49All Fatal/ Injury 15 87

100(1-(1.06+3(SD-0.02))); SD=superelevation deficiency 0.02

Improve horizontal and vertical alignmentsImprove longitudinal gradeImprove superelevation (for drainage)Flatten side slopes (27 to 14 degrees)Improve superelevationImprove curve superelevationImprove gore area

100(1-(1.00+6(SD-0.01))); SD=superelevation deficiency and 0.02

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All <5,000/lane 15 20All All >5,000/lane 15 31All All 15 10All All 15 20All All 15 22All All 15 25All All 15 25All All 15 25All Fatal 15 39All Injury 15 23All PDO 15 27

Head-on All <5,000/lane 15 38Head-on All >5,000/lane 15 44Head-on All 15 53Head-on All 15 53Head-on PDO 15 50

Left-turn All 15 71Left-turn PDO 15 67

ROR All 15 44ROR All 15 26ROR All 15 44ROR All 15 44ROR PDO 15 50

Overturn All <5,000/lane 15 42Overturn All >5,000/lane 15 52

Rear-end All <5,000/lane 15 42Rear-end All >5,000/lane 15 52Rear-end All 15 32Rear-end All 15 32Rear-end All 15 40Rear-end All 15 53Rear-end PDO 15 53

Increase number of lanes

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Rightangle All <5,000/lane 15 35Rightangle All >5,000/lane 15 45

Rightangle All 15 15Rightangle PDO 15 46

Sideswipe All <5,000/lane 15 38Sideswipe All >5,000/lane 15 44Sideswipe All 15 30Sideswipe All 15 30Sideswipe All 15 35Sideswipe PDO 15 64

Increase vertical grade by 1% All All Rural 2-lane 23

All All 15 26All All All All 1 10All All 15 10All All 15 10All All 15 10All All 15 25All All 15 75

Rear-end All 15 75

Sideswipe All 15 75

All All 15 67All PDO 15 62

Rear-end All 15 93

Install climbing lane (where large difference between car and truck speed)

All Fatal/ Injury Rural 2-lane 38 33

-1.6P; P=percent grade (abso

Install acceleration/ deceleration lanesInstall channelized laneIncrease number of lanes (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All All All 1 20All Fatal/ Injury Rural 2-lane 38 33

Install shoulder All All 15 9

Head-on Fatal/ Injury 15 50

Head-on PDO 15 86

Left-turn Fatal/ Injury 15 42

Left-turn PDO 15 57

ROR PDO 15 27

Rightangle Fatal/ Injury 15 34Rightangle PDO 15 31

Sideswipe Fatal/ Injury 15 27

Sideswipe PDO 15 8

All All 15 18

ROR All 15 75

Rear-end All 15 33

All All 15 44All All 15 40All All 15 48All All 15 30All All Urban 4-lane highway 8,000-17,400 17 37 1 

All All 4-lane 42 26 All Fatal/ Injury Urban 4-lane highway 8,000-17,400 17

0

2 

All PDO Urban 4-lane highway 8,000-17,400 17 46 1 

Install passing/climbing laneInstall shoulder bus lanesInstall truck escape rampLengthen culvertsNarrow cross section (4 to 3 lanes with two way left-turn lane)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Left-turn All Urban 4-lane highway 8,000-17,400 17 24

2 

Rear-end All Urban 4-lane highway 8,000-17,400 17 31

2 

Rightangle All Urban 4-lane highway 8,000-17,400 17 37 1 

All All 15 38All All 15 40

Reduce shoulder width (6 ft to 0 ft) All All Rural 2-lane 20 -12 3 Reduce shoulder width (6 ft to 1 ft) All All Rural 2-lane 20 -17 6 Reduce shoulder width (6 ft to 2 ft) All All Rural 2-lane 20 -11 2 Reduce shoulder width (6 ft to 4 ft) All All Rural 2-lane 20 -6 2 Reduce shoulder width (6 ft to 5 ft) All All Rural 2-lane 20 -2 2Reduce vertical grade by 1% All All Rural 2-lane 23 

All All 15 28

Wet 

pavement All 15 51

Stabilize shoulder All All 15 25Stabilize shoulder and dropoff All All All All 1 25

All All Freeway 6All All Rural Rural Highway

6

100(1-(EXP(bPg-1.0)1.0+1.0)b=regression coefficient (for vrefer to source)., Pg=percent g(absolute value).100(1-((EXP(bPg)-1.0)Ps+1.0b=regression coefficient (for vrefer to source), Pg=percent gvalue), Ps=proportion of crash (for values of Ps, refer to sour1.6P; P=percent grade (absol

Vary gradeResurface pavement and improve superelevationReduce horizontal curve angleNarrow cross section (4 to 3 lanes with two way left-turn lane) (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Vary horizontal curvature All All Rural Rural Highway

6

All All Freeway 6All All Rural Rural Highway

6

All All Freeway 6All All Rural Rural Highway

6

All All Urban Urban Street 6

100(1-((EXP(-0.040(Wl-12))-1.0)(Pi/0.24)+1.0)); Wl=lane wPi=proportion of crash type suvalues of Pi, refer to source)100(1-((EXP(-0.047(Wl-12))-1.0)(Pi/0.37)+1.0)); Wl=lane wPi=proportion of crash type suvalues of Pi, refer to source).100(1-((EXP(-0.021(Wis-Wsb1.0)(Pi/0.15)+1.0)); Wis=inside width (ft), Wsb=base inside sh(ft) (=4.0 for four lanes, 10.0 folanes), Pi=proportion of crash (for values of Pi, refer to sourc100(1-((EXP(-0.021(Wis-4))-1.0)(Pi/0.16)+1.0)); Wis=inside width (ft), Pi=proportion of cra(for values of Pi, refer to sourc

Vary inside shoulder width

100(1-((1.55Lc+80.2/R-0.012ILc=length of horizontal curve radius (ft), Is=presence of a spcurve (1 if a spiral transition is otherwise).

Vary lane width

100(1-((EXP(-0.047(Wl-12))-1.0)(Pi/0.36)+1.0)); Wl=lane wPi=proportion of crash type suvalues of Pi, refer to source).

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All Freeway 6All All Rural Rural Highway

6

Vary shoulder width All All Urban Urban Street 6Vary side slopes All All Rural Rural Highway

6

Vary spiral transition curvature All All Rural Rural Highway

6

Vary superelevation All All Rural Rural Highway

6

Vary uncurbed crosssections All All Urban Urban Street 6

Head-on All 15 12

ROR All 15 12

Sideswipe All 15 12

Head-on All 15 23

ROR All 15 23

100(1-((EXP(-0.021(Ws-10))-1.0)(Pi/0.15)+1.0)); Ws=outsidwidth (ft), Pi=proportion of cra(for values of Pi, refer to sourc

Widen lane (add 1 ft to both sides)Widen lane (add 2 ft to both sides)

100(1-((EXP(-0.074)(1-Poff-ro0.225)Poff-road)); Poff-road=poff-road crashes.

Vary outside shoulder width 100(1-((EXP(-0.021(Ws-8))-

1.0)(Pi/0.16)+1.0)); Ws=outsidwidth (ft), Pi=proportion of cra(for values of Pi, refer to sourc100(1-((EXP(-0.014(Ws-1.5))-1.0)(Pi/0.088)+1.0)); Ws=shouPi=proportion of crash type suvalues of Pi, refer to source).100(1-((EXP(0.692(1/Ss-0.25)1.0)Ps+1.0)), Ss= horizontal rchange in elevation (average segment, ft), Ps=proportion of subset (for values of Ps, refer 100(1-((1.55Lc+80.2/R0.012)/(1.55Lc+80.2/R))); Lc=horizontal curve (mi), R=curve 0 through -15 according to the superelevation deficiency (refe

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Widen lane (add 2 ft to both sides) (cont'd) Sideswipe All 15 23

Head-on All 15 32

ROR All 15 32

Sideswipe All 15 32

Head-on All 15 40

ROR All 15 40

Sideswipe All 15 40

Widen lane (initially less than 9 ft) All Fatal/ Injury Rural 2-lane 400-2,000 38 28 

Widen lane (initially between 9 ft and 10.75 ft)

All Fatal/ Injury Rural 2-lane 400-2,000 38 16 

All All All 15 56All All Rural 21 All All 15 50

Fixed 

object All 15 5

Head-on All 15 70Head-on All 15 5Head-on All 15 70

ROR All 15 49

Widen lanesWiden lane (add 3 ft to both sides)Widen lane (add 4 ft to both sides)

100(1-((AMFRA-1.0)PRA+1.0AMFRA=accident modification related accidents (for values orefer to source), PRA=proportcrashes constituted by related 

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Overturn All 15 5

Sideswipe All 15 52Sideswipe All 15 5Sideswipe All 15 52

Widen shoulder (from 6 to 7 ft) All All Rural 2-lane 20 -1 4

Widen shoulder (from 6 to 8 ft) All All Rural 2-lane 20 4 2Widen shoulder (from 6 to 9 ft) All All Rural 2-lane 20 21 6Widen shoulder (from 6 to >9 ft) All All Rural 2-lane 20 18 3Widen shoulder All All All All 1 20Widen shoulder (initially less than 1 ft) All Fatal/ Injury Rural 2-lane 400-2,000 38 25 

Widen shoulder (initially between 1 ft and 3.3 ft) All Fatal/ Injury Rural 2-lane 400-2,000 38 13 

Widen shoulder (initially less than or equal to 4 ft) All All All All 1 20

Widen shoulder (initially more than 4 ft) All All All All 1 35

All All 15 29All All 15 57All All 15 20All All 15 8All All 15 32All All 15 50

Fixed 

object All 15 15

Head-on All 15 45Head-on All 15 75

Widen lanes (cont'd)Widen shoulder (paved)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Head-on All 15 15

ROR All 15 60

Ped All 15 71

Sideswipe All 15 28Sideswipe All 15 41Sideswipe All 15 15

Fixed 

object All 15 16

ROR All 15 16

Fixed 

object All 15 29

ROR All 15 29

Fixed 

object All 15 40

ROR All 15 40

Fixed 

object All 15 49

ROR All 15 49

All All Rural 2-lane 15 15All All 15 22

Fixed 

object All 15 13

ROR All 15 13

Fixed 

object All 15 25

ROR All 15 25

Fixed 

object All 15 34

ROR All 15 34

Fixed 

object All 15 43

ROR All 15 43

Widen shoulder (paved) (from 0 to 2 ft)Widen shoulder (unpaved)Widen shoulder (paved) (from 0 to 4 ft)Widen shoulder (paved) (from 0 to 6 ft)Widen shoulder (paved) (from 0 to 8 ft)Widen shoulder (unpaved) (from 0 to 2 ft)Widen shoulder (unpaved) (from 0 to 4 ft)Widen shoulder (unpaved) (from 0 to 6 ft)Widen shoulder (unpaved) (from 0 to 8 ft)Widen shoulder (paved) (cont'd)

FHWA-SA-07-015 September 2007 
Table 7: Median Countermeasures
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All All All 1 15All Fatal/ Injury Rural 2-lane 5 -94 56 

All Fatal/ Injury Urban 2-lane 5 39 10 

All Injury Rural Multilane 5 12 3 

All Injury Urban Multilane 5 22 2 

All PDO Rural Multilane 5 18 3 

All PDO Rural 2-lane 5 -128 55 

All PDO Urban Multilane 5 -9 2 

All All <5,000/lane 15 44All All >5,000/lane 15 52All All All All 1 25All All 15 15All All 15 15All Fatal 15 90

Left-turn All <5,000/lane 15 72Left-turn All >5,000/lane 15 78

All All All All 27 86

3 

All All Multilane divided 5 -24 3 

All All 15 19All All All All 1 5All All 15 5All All 15 15All All 15 19All All 15 20

Install median barrierInstall median (flush)

MEDIAN COUNTERMEASURES

Install median

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All 15 25All All 15 25All All 15 36All Fatal Multilane divided 5 43 10 

All Fatal All All 1 65All Fatal 15 65All Fatal/ Injury All All 27 88

5 

All Injury Multilane divided 5 30 6 

All Injury All All 1 40All Injury 15 40

ROR All 15 35

Rightangle All <5,000/lane 15 58Rightangle All >5,000/lane 15 54

All All Highway (three-lane) 5 -34 74 

All Fatal Highway (three-lane) 5 100 254 

All Injury Highway (three-lane) 5 26 84 

All Injury Multilane divided 5 29 11 

Head-on Fatal Rural Highway 9 92 

All Fatal 15 90All Injury Multilane divided 5 -15 36 

All Injury 15 10

Install median barrier (cont'd)Install median barrier (concrete)Install median barrier (cable)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Install median barrier (steel) All Injury Multilane divided 5 35 8 

All All <5,000/lane 15 17All All >5,000/lane 15 17All All 15 17

ROR All <5,000/lane 15 56ROR All >5,000/lane 15 56ROR All 15 56

Rear-end All <5,000/lane 15 39Rear-end All >5,000/lane 15 39Rear-end All 15 39

All All 15 20All All 15 25

Head-on All 15 75

Ped All 15 25

All All Urban Urban Street 6All All Rural Rural Highway

6

All All Freeway 6

Vary median widthInstall raised median

100(1-((b0(EXP(b1Wm^b2)-1.0)+1.0)/(b0(EXP(b1Wmb^b2b0, b1, and b2=regression coevalues of b0, b1, and b2, refer Wm=median width (ft), Wmb=width (ft) (16 for surfaced meddepressed median).100(1-((b0(EXP(b1Wm^b2)-1.0)+1.0)/(b0(EXP(b1Wmb^b2b0, b1, and b2=regression coevalues of b0, b1, and b2, refer Wm=median width (ft), Wmb=width (ft) (24 for surfaced meddepressed median).

Install or upgrade median barrier near gore area

100(1-((b0(EXP(b1Wm^b2)-1.0)+1.0)/(b0(EXP(b1x16b^b2b0, b1, and b2=regression coevalues of b0, b1, and b2, refer Wm=median width (ft).

FHWA-SA-07-015 September 2007 
Table 8: Roadside Countermeasures
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All 15 40All All All All 1 40

Snow All 15 53Snow All 15 71Snow All 15 35

Remove poles by burying utility lines All All 15 40Remove obstacles on curves to improve sight distance

All Fatal/ Injury Rural 2-lane 38 5

All All All All 27 38 10 

All All <5,000/lane 15 18All All >5,000/lane 15 17All All All All 1 30All All All All 1 25All All 15 29All All 15 35All All 15 61All All 15 20All All 15 25All All 15 30All All 15 30All All 15 55All All 15 25All Fatal All All 1 50All Fatal All All 1 40All Fatal 15 40All Fatal 15 50All Fatal 15 40All Fatal 15 50All Fatal/ Injury All All 27 38 13 

All Injury All All 1 30

Remove or relocate fixed objects outside of clear zone

ROADSIDE COUNTERMEASURES

Install snow fencingInstall frontage road

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All Injury All All 1 25All Injury 15 25All Injury 15 30All Injury 15 25All Injury 15 30

Fixed 

object All 15 65

Fixed 

object All Urban 15 20

Fixed 

object All <400 15 40

Fixed 

object All 15 88

Fixed 

object All 15 90

Fixed 

object All 15 100

Fixed 

object All 15 75

ROR All 15 71

Overturn All <5,000/lane 15 42Overturn All >5,000/lane 15 44

Vary horizontal clearance All All Rural Rural Highway

6

Vary utility pole density All All Freeway 6

100(1-((EXP(-0.0137(Whc-301.0)Ps+1.0)); Whc=horizontal (average for length of segmenPs=proportion of crash type svalues of Ps, refer to source).100(1-((fp-1.0)Ps+1.0)); fp=((0.0000984ADT+0.0354D0.04)/(0.0000128ADT+0.075)pole density (two-way total) (p=average pole offset from neatraveled way (ft), Ps=proportiotype subset (for values of Ps, source).

Remove or relocate fixed objects outside of clear zone (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All Rural Rural Highway

6

All All Urban Urban Street 6

Widen clear zone (add 5 ft)

Fixed 

object All 15 13

Widen clear zone (add 8 ft)

Fixed 

object All 15 21

Widen clear zone (add 10 ft)

Fixed 

object All 15 25

Widen clear zone (add 15 ft)

Fixed 

object All 15 35

Widen clear zone (add 20 ft)

Fixed 

object All 15 44

100(1-((fp-1.0)Ps+1.0)); fp=((0.0000984ADT+0.0354D0.04)/(0.0000128ADT+0.075)pole density (two-way total) (p=average pole offset from neatraveled way (ft), Ps=proportiotype subset (for values of Ps, source)100(1-(0.022(fp-1.0)+1.0)), fp=((0.0000984ADT+0.0354D0.04)/(0.0000649ADT+1.128)pole density (two-way total) (pWo=average pole offset from of traveled way (ft) 

Vary utility pole density (cont'd)

FHWA-SA-07-015 September 2007 
Table 9: Signs / Markings / Operational Counterme
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All Injury Urban Local 5 15 10 

All PDO Urban Local 5

7

6 

All Fatal/ Injury Rural 2-lane 38 20

All All 15 35All All Urban Arterial (urban) 5 64 49 

All All 15 20All All 15 35All All 15 50All Fatal/ Injury Rural 2-lane 38 10

All Injury 5 30 71 

All PDO 5 8 76 

All All 15 30All Fatal 15 55All All 15 30All All 15 23All Injury 15 20

Head-on All 15 29

ROR All 15 30ROR All All All 1 30

All Injury 5 13 9 

All PDO 5 29 23 

All All 15 29All All 15 20

Install chevron signs on horizontal curves

SIGNS

Install curve advance warning signs (advisory speed)Install curve advance warning signsImplement sign corrections to MUTCD standards

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Install curve advance warning signs (flashing beacon)

All All 15 30All All 15 11

Head-on All 15 67

Night All 15 25

ROR All 15 34

Sideswipe All 15 67

All Injury Freeways 5 44 17 

Rear-end Injury Freeways 5 16 10 

Install dynamic/variable queue warning signs Rear-end PDO Freeways 5 -16 15 

All All 5 46 17 

All Injury 5 41 62 

Install guide signs (general) All All All 15 15Install guideposts or barrier reflectors All Fatal/ Injury Rural 2-lane 38 8

Install illuminated signs All All 15 15

Rear-end All 15 10

Sideswipe All 15 20

All All 15 10

Night All 15 25

Install dynamic/variable accident warning signsInstall delineators (general)Install nonvehicular (animal) reflectorsInstall lane assignment signsInstall dynamic/variable speed warning signs

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All 15 5

Wet 

pavement All 15 20

Wet 

pavement All 15 20

Wet 

weather All All All 1 20

All All 15 25All All 15 20All All 15 25All All 15 30

Night All All All 1 30

All Injury Rural 2-lane 5 -4 10 

All PDO Rural 2-lane 5 -5 7 

All All 15 25All All 15 13

Ped All 15 10

All All 15 22All All All All 1 25All All 15 18All All 15 25All All 15 25All Fatal/ Injury 15 18

All PDO 15 17

ROR All 15 27ROR All 15 27

All All 15 21All All <5,000/lane 15 37All All >5,000/lane 15 21All All All All 1 25All All 15 10

Install post-mounted delineators (tangents and curves combined)

PAVEMENT

Improve pavement frictionImprove pavement friction (groove shoulder)Improve pavement friction (grooving)Install post-mounted delineators (curves)Install pavement condition warning signs

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All 15 14All All 15 25

Fixed 

object All <5,000/lane 15 36

Fixed 

object All >5,000/lane 15 19

ROR All <5,000/lane 15 41ROR All >5,000/lane 15 40

Overturn All <5,000/lane 15 54Overturn All >5,000/lane 15 35

Rear-end All <5,000/lane 15 54Rear-end All >5,000/lane 15 35

Wet 

pavement All 15 60

Wet 

pavement All <5,000/lane 15 64

Wet 

pavement All >5,000/lane 15 54

Wet 

pavement All All All 1 60

Wet 

pavement All All All 1 45

Wet 

pavement

Fatal/ 

Injury Rural 2-lane 38 30

All All <5,000/lane 15 13All All >5,000/lane 15 20

Fixed 

object All <5,000/lane 15 43

Fixed 

object All >5,000/lane 15 34

Head-on All <5,000/lane 15 43Head-on All >5,000/lane 15 61Head-on Fatal/ Injury 15 19

Head-on PDO 15 30

Improve pavement friction (grooving) (cont'd)Improve pavement friction (increase skid resistance)Improve pavement friction (overlay)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Left-turn Fatal/ Injury 15 41

Left-turn PDO 15 34

ROR Fatal/ Injury 15 28

ROR PDO 15 29

Rear-end Fatal/ Injury 15 12

Rear-end PDO 15 21

Rightangle Fatal/ Injury 15 11Rightangle PDO 15 31

Sideswipe All <5,000/lane 15 43Sideswipe All >5,000/lane 15 61Sideswipe Fatal/ Injury 15 12

Sideswipe PDO 15 27

Wet 

pavement All <5,000/lane 15 23

Wet 

pavement All >5,000/lane 15 50

All All 15 17All All 15 10All All 15 24

Head-on All 15 86

Wet 

pavement All 15 51

23 Right- angle All

Improve pavement friction (curve overlay)

15

Improve pavement friction (overlay) (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Improve pavement friction (resurface with deicing additives)

Head-on All 15 31

All All 15 75

Fixed 

object All 15 93

Head-on All 15 90

Sideswipe All 15 90

Wet 

pavement All 15 91

Improve pavement friction (skid treatment with overlay)

Ped Fatal/ Injury 15 3

All All Rural 2-lane 5,000-22,000 5 14

5 

All Injury Rural 2-lane 5,000-22,000 5 15

8 

Head-on All Rural 2-lane highway 26 55 

Head-on Fatal Rural 2-lane highway 26 68 

Head-on Injury (minor) Rural 2-lane highway 26 26 Head-on Injury (major) Rural 2-lane highway 26 33 

Install centerline rumble stripsImprove pavement friction (resurface with open-graded mix)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Head-on/ 

Sideswipe All Rural 2-lane 5,000-22,000 5 21 12 

Head-on/ 

Sideswipe Injury Rural 2-lane 5,000-22,000 5 25 15 

Install or upgrade curbing

Fixed 

object All 15 50

All All Rural Multilane divided 8 16 

All Injury Rural Multilane divided 8 17 

ROR All Rural 2-lane >4,000 41 13 8ROR All Rural Multilane divided 8 10 

ROR All Rural Highway 16 27 22 ROR All All Freeway 19 18 7

ROR All Rural Freeway 19 21 10ROR All Rural All 57 34ROR All Rural Arterial 57 16ROR All Rural Between 

ramps

57 34

ROR All Rural Highway 57 38ROR All Rural Three-lane 57 36ROR All Rural 2-lane 57 32ROR Fatal/ Injury Rural 2-lane >4,000 41 18 12ROR Injury Rural Multilane divided 8 22 ROR Injury All Freeway 19 13 12

Install shoulder rumble stripsInstall centerline rumble strips (cont'd)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Install shoulder rumble strips (cont'd) ROR Injury Rural Freeway 19 7 16

Install shoulder rumble strips on illuminated highways

ROR All Rural All 57 41

Install shoulder rumble strips on unilluminated highways

ROR All Rural All 57 31

All All 15 15

Head-on All 15 86

Night All 15 62

Vary centerline rumble strip width All All Rural Rural Highway 6 12 6

All All Rural Rural Highway

6

All All Freeway 6

Delineate multiple lanes (painted lane lines) All All Urban Multilane 13 18 22 

All All 15 33All All All All 1 36All All 15 35All All 15 30All Injury All 2-lane 13 1 6 

All PDO All 2-lane 13 -1 5 

All All Urban 18 38 6 

All Injury Freeways 5 56 26 

Install chevron converging pattern markings on pavement

100(1-(-0.07Pi+1.0)); Pi=proptype subset (for values of Pi, rsource).

MARKINGS

100(1-(-0.12Pi+1.0)); Pi=propinfluential crashes that occur otype i

Install centerline markingsPave shoulderVary shoulder rumble strips

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All Rural Undivided 1,000-4,000 2 -3 21 

All Injury All All 13 24 11 

Install edgelines, centerlines and delineators

All Injury All All 13 45 11 

All All <5,000/lane 15 44All All >5,000/lane 15 38All All All All 1 20All All 15 24All All 15 30All All 15 4All All 15 15All All 15 15All All 15 25All Injury 15 15All PDO 15 8

Fixed 

object All <5,000/lane 15 66

Fixed 

object All >5,000/lane 15 59

ROR All 15 30ROR All All All 1 25

Overturn All <5,000/lane 15 45Overturn All >5,000/lane 15 50

Rear-end All <5,000/lane 15 45Rear-end All >5,000/lane 15 50

All Injury Rural 2-lane 13 3 4 

All PDO Rural 2-lane 13 3 11 

All Injury Rural 2-lane 13 -5 8 

All PDO Rural 2-lane 13 1 15 

Install edgelines and centerlinesInstall edgeline markings (8 in) Install edgeline markings (from 4 to 6 in)Install edgeline markings

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Night All Rural 4-lane freeway

≤20000 4 -13 14 

Night All Rural 4-lane freeway <60000 4 33 21 

Night All Rural 4-lane freeway 20,001- 60,000 4 6 21 

Night All Rural 2-lane, DOC>3.5

≤5,000 4 -43

9 

Night All Rural 2-lane, DOC>3.5 5,001-15,000 4 -26 10 Night All Rural 2-lane, DOC>3.5 15,001- 20,000 4 -3 11 Night All Rural 2-lane, DOC<3.5

≤5,000 4 -16

3 

Night All Rural 2-lane, DOC<3.5 5,001-15,000 4 1 5 Night All Rural 2-lane, DOC<3.5 15,001- 20,000

4 24

7 

All All 15 53

Head-on All 15 40

Sideswipe All 15 40

All All All All 40 -7 

Fatal/injury All All All 40 -5 

Lower posted speed by 5 mph All All All All 40 -44 

Lower posted speed by 10 mph All All All All 40 7 

Lower posted speed by 15-20 mph All All All All 40 5 

Install raised pavement markers (snowplowable) where DOC = Degree of CurvatureInstall no-passing line

REGULATORY

Lower posted speed

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All Urban Arterial (64ft) 30,000 5 42 8 

All All 15 22All All 15 8All All 15 35All Injury Urban Arterial 5 20 5 

All Injury Urban Arterial (64ft) 30,000 5 35 14 

All PDO Urban Arterial 5 27 2 

All PDO Urban Arterial (64ft) 30,000 5 48 1 

Fixed 

object All 15 40

All All All All 40 11 

Fatal/injury All All All 40 7 

Raise posted speed by 5 mph All All All All 40 8 

Raise posted speed by 10-15 mph All All All All 40 15 

All Fatal All All 5 17 5 All Injury All All 5 7 3 All PDO All All 5 5 4 All Fatal All All 5 32 9 All Injury All All 5 15 5 All PDO All All 5 10 8 All Fatal All All 5 44 14 All Injury All All 5 22 8 All PDO All All 5 15 12 

Raise posted speedProhibit on-street parkingReduce mean speed by 5% through speed limit change and enforcementReduce mean speed by 10% through speed limit change and enforcementReduce mean speed by 15% through speed limit change and enforcement

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Vary curb parking extent All All Urban Urban Street 6

All All Freeway 6All All Urban Urban Street 6

100(1-EXP(-0.012(V-55))); V=(mph)

Vary speed limit

100(1-((EXP(0.252IV<=30+0.318IV>road+1.15((V^2.066)(Exp(-0.0

road)))); Poff-road=proportion that occur off the roadway, for IV<=30 and IV>=45, refer to s(EXP(b(V-40)))); b= vary per rV=Speed limit (mph).100(1-(1+Ppk(Bpk-1))), Bpk=(1.10+0.365Iu2+0.609Pb1.0)Pap+1.0); Ppk=proportion segment length with parallel oparking (=0.5 Lpk/L), Lpk=curallocated to parking (mi), Iu2=variable for cross section(1 fostreet; 0 otherwise), Pb/o=for street with parking, the proporbusiness or office as an adjacfap/pp=ratio of crashes on streparking to those on streets witparking, Pap= for that part of tparking, the proportion with an

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All All All 1 25All All 15 23All All 15 20All All 15 25All Fatal All Freeway 5 73 71 

All Fatal All Highway 5 69 36 

All Fatal Rural Highway 5 73 72 

All Fatal Urban Highway 5 63 52 

All Injury All Freeway 5 27 12 

All Injury All Highway 5 28 6 

All Injury Rural Highway 5 20 12 

All Injury Urban Highway 5 31 7 

All PDO All Freeway 5 32 26 

All PDO All Highway 5 18 7 

All PDO Rural Highway 5 30 43 

All PDO Urban Highway 5 16 8 

Night All 15 37Night All 15 20Night All 15 45Night All 15 45

LIGHTING

Improve lighting

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All All All 27 50 17 

All Fatal/ Injury All All 27 26 38 

All All All 27 8 16 

All All All 1 34 All All 15 30 

All All 15 25 

All All 15 35 

All All 15 34 

All All 15 25 

All Fatal/ Injury All 27 20 25 

All Injury 15 20 

All PDO 15 35 

Head-on All 15 36Head-on Fatal/ Injury 15 67 

Head-on PDO 15 64 

Left-turn All 15 33Left-turn All 15 33 Left-turn Fatal/ Injury 15 17 

Add two-way left-turn lane

OPERATIONAL

Install lighting at interchanges

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Left-turn PDO 15 38 

ROR All 15 37ROR Fatal/ Injury 15 90 

ROR PDO 15 16 

Ped All 15 19

Rear-end All 15 36Rear-end All 15 36 

Rear-end All 15 36 

Rear-end Fatal/ Injury 15 32 

Rear-end PDO 15 38 

Rightangle All 15 20 

Rightangle Fatal/ Injury 15 31 

Rightangle PDO 15 23 

Sideswipe Fatal/ Injury 15 32 

Sideswipe PDO 15 37 

All All 15 43All All All All 1 33

Implement crossover at work zone All All 4-lane divided 6,800-38,000 12 0 

Add two-way left-turn lane (cont'd)Convert from two-way to one-way traffic

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

Head-on All 15 31

Left-turn Fatal/ Injury 15 37

Left-turn PDO 15 13

ROR Fatal/ Injury 15 19

ROR PDO 15 30

Ped Fatal/ Injury 15 33

Ped PDO 15 42

Rear-end Fatal/ Injury 15 21

Rightangle Fatal/ Injury 15 16Rightangle PDO 15 23

Sideswipe PDO 15 29

Implement single lane closure at work zone All All 4-lane divided 20,000- 41,500 12 -56 

All All 15 32All All All All 1 20All All 15 20

Wet 

pavement All 15 40

Ped All 15 74Ped All 15 75Ped All 15 89Ped All 15 65Ped All 15 65

Implement maintenance and bituminous overlayImprove drainage patternsInstall sidewalk

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors Roa

Daily Traffic 

Volume 

(veh/day)

Road Type 

Crash Type Countermeasure(s) Area Type Crash Reduction Factor / Function Crash Severity 

Effectiveness

Ref Std 

Erro

All All 2-lane 15 32All Injury 2-lane 15 59

Left-turn All 2-lane 15 46

Rear-end All 2-lane 15 46

Sideswipe All 2-lane 15 46

All All Urban Freeway 77,000- 126,000

5 -11

5 

All Fatal/ Injury Urban Freeway 77,000- 126,000 5 -11 8 

All

Fatal/ 

Injury/ 

PDO

Urban Freeway 77,000- 126,000

5 -10

7 

All All Urban Freeway 77,000- 126,000

5 -3

8 

All Fatal/ Injury Urban Freeway 77,000- 126,000 5 -7 13 

All

Fatal/ 

Injury/ 

PDO

Urban Freeway 77,000- 126,000 5 -4 11 

Reduce driveway density (general) All All Urban Urban Street 6Remove unwarranted signals (one-way streets) Ped All 46 17

Vary passing lanes All All Rural Rural Highway

6

Vary truck presence All All Urban Urban Street 6Reconfigure lanes within existing pavement width (five to six in one direction)Reconfigure lanes within existing pavement width (four to five in one direction)

100(1-((ftk-1.0)(1-Poff-road)+1ftk=(2EXP(-0.059Pt)+0.017Pt)road=proportion of crashes throadway, Pt=percent of truck 100(1-(1.0+Truck/Basei)), for Truck and Basei, refer to sour0.25 for one direction with threfor two direction with four lane100(1-(EXP(0.008(Dd,b/o-50)density of driveways serving boffice land uses (driveways/m

Reconfigure lanes within existing pavement width (two to three in one direction)

FHWA-SA-07-015 September 2007 
Tables for Pedestrian Crash Reduction Facto
Table 10: Signalization Countermeasures
Desktop Reference for Crash Reduction Factors 

Add exclusive pedestrian phasing Pedestrian All 28 34 

All Fatal/Injury 49 12 9

Pedestrian Fatal/Injury 49 37

Install pedestrian countdown signal heads Pedestrian Fatal/Injury Urban (San Francisco) 32 25

All All 15 20

Pedestrian All 15 53Pedestrian All 5 0

All All 15 25All All 15 15

Pedestrian All 15 55Pedestrian All 15 50

Modify signal phasing (implement a leading pedestrian interval)

Pedestrian All 28 5

Remove unwarranted signals (one-way street) Pedestrian All 46 17

Install pedestrian signal

Std 

Error 

SIGNALIZATION COUNTERMEASURES

Improve signal timing [to intervals specified by the ITE Determing Vehicle Change Intervals: A Proposed Recommended Practice (1985)]

Obs

Effectiven

Crash Reduction Factor / 

Function

Crash Type Crash Severity Countermeasures Area Type Ref

FHWA-SA-07-015 September 2007 
Table 11: Geometric Countermeasures
Desktop Reference for Crash Reduction Factors 

Std 

Error 

Obs

Effectiven

Crash Reduction Factor / 

Function

Crash Type Crash Severity Countermeasures Area Type Ref

Convert unsignalized intersection to roundabout Pedestrian Fatal/Injury Urban 11 27 12 

Convert intersection to roundabout Pedestrian All 55 89

Pedestrian All 15 86Pedestrian All 1 14 90 Pedestrian Fatal/Injury 15 90Pedestrian PDO 15 90Pedestrian All 15 100Pedestrian All 15 67Pedestrian All 15 5Pedestrian All 15 90

Install pedestrian overpass/underpass 

(unsignalized intersection)

Pedestrian All 28 13

Install raised median Pedestrian All 15 25Install raised median (marked crosswalk) Pedestrian All 60 46Install raised median (unmarked crosswalk) Pedestrian All 60 39Install raised median (unsignalized intersection) Pedestrian All 28 69

All All 5 30 67 All Fatal/Injury 5 36 54 

Pedestrian All 28 8

Install refuge islands Pedestrian All 28 56

Pedestrian All 15 74Pedestrian All 36 88 

GEOMETRIC COUNTERMEASURES

Install raised pedestrian crossingInstall pedestrian overpass/underpassInstall sidewalk (to avoid walking along roadway)

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Std 

Error 

Obs

Effectiven

Crash Reduction Factor / 

Function

Crash Type Crash Severity Countermeasures Area Type Ref

Pedestrian All 15 75Pedestrian All 15 89Pedestrian All 15 65Pedestrian All 15 65

Provide shoulder (paved) Pedestrian All 15 71Install sidewalk (to avoid walking along roadway) (cont'd)

FHWA-SA-07-015 September 2007 
Table 12: Signs / Markings / Operational Counterm
Desktop Reference for Crash Reduction Factors 

Std 

Error 

Obs

Effectiven

Crash Reduction Factor / 

Function

Crash Type Crash Severity Countermeasures Area Type Ref

Pedestrian All 15 39Pedestrian All 21 69 19

Pedestrian All Urban 30 39 

Pedestrian Fatal 13 78 87 Pedestrian Injury 13 42 18 

Improve pavement friction Pedestrian All 15 10Improve pavement friction (skid treatment with overlay) Pedestrian Fatal/Injury 15 3Increase enforcement to reduce speed Pedestrian All 28 70Install far-side bus stops (signalized intersection) Pedestrian All 28 1Install object markers Pedestrian All 15 29

All All 15 18All All 15 15All All 15 20All All 15 15All All 15 20

Improve lighting at intersections

SIGNS / MARKINGS / OPERATIONAL COUNTERMEASURES

Convert two-way to all-way STOP controlInstall school zone warning signs

FHWA-SA-07-015 September 2007 
Desktop Reference for Crash Reduction Factors 

Std 

Error 

Obs

Effectiven

Crash Reduction Factor / 

Function

Crash Type Crash Severity Countermeasures Area Type Ref

Pedestrian All New Orleans 5 -81 88 

Pedestrian All New York 5 -43 24 

Pedestrian All Ohio 5 -57 31 

Pedestrian All Wisconsin 5 -108 51 

Prohibit left-turns Pedestrian All 15 10Remove marked unprotected crosswalks from arterial intersections

Pedestrian All Urban 5 73

Restrict parking near intersections (to off-street) Pedestrian All 15 30Permit right-turn-on-red

FHWA-SA-07-015 September 2007 
September 2007 

References 1 Agent, K. R., Stamatiadis, N., and Jones, S., "Development of Accident Reduction Factors." KTC-96-13, Kentuck

2 Al-Masaeid, H. R. and Sinha, H., "An Analysis of Accident Reduction Potentials of Pavement Marking." Journa

ASCE, (1993) pp. 723-736. 

3 Antonucci, N. D., Hardy, K. K., Slack, K. L., Pfefer, R., and Neuman, T. R., "NCHRP Report 500 Volume 12: A 

at Signalized Intersections." Washington, D.C., Transportation Research Board, National Research Council, (2

4 Bahar, G., Mollett, C., Persaud, B., Lyon, C., Smiley, A., Smahel, T., and McGee, H., "NCHRP Report 518: Sa

Raised Pavement Markers." Washington, D.C., Transportation Research Board, National Research Council, (2

5 Bahar, G., Parkhill, M., Hauer, E., Council, F., Persaud, B., Zegeer, C., Elvik, R., Smiley, A., and Scott, B. "Pre

Safety Manual: Knowledge Base for Part II". Unpublished material from NCHRP Project 17-27. (May 2007) 

6 Bonneson, J., Zimmerman, K., and Fitzpatrick, K., "Roadway Safety Design Synthesis." Texas Transportation 7 Brich, S. C. and Cottrell Jr, B. H., "Guidelines for the Use of No U-Turn and No-Left Turn Signs." VTRC 95-R5

Department of Transportation, (1994) 

8 Carrasco, O., McFadden, J., and Chandhok, P., "Evaluation of the Effectiveness of Shoulder Rumble Strips on 

Highways In Minnesota." 83rd Transportation Research Board Annual Meeting, Washington D.C., (2004) 

9 Chandler, B., "Eliminating Cross-Median Fatalities: Statewide Installation of Median Cable Barrier in Missouri." 

Washington, D.C., Transportation Research Board of the National Academies, (2007) pp. 29-31. 

10 Clark, J. E., Maghsoodloo, S., and Brown, D. B., "Public Good Relative to Right-Turn-on-Red in South Carolin

Research Record 926, Washington, D.C., Transportation Research Board, National Research Council, (1983) 

11 De Brabander, B. and Vereeck, L., "Safety Effects of Roundabouts in Flanders: Signal type, speed limits and v

1407, Elsevier Science, (2006) 

12 Dudek, C. L., Richards, S. H., and Buffington, J. L., "Some Effects of Traffic Control on Four-Lane Divided Hig

Research Record 1086, Washington, D.C., Transportation Research Board, National Research Council, (1986

13 Elvik, R. and Vaa, T., "Handbook of Road Safety Measures." Oxford, United Kingdom, Elsevier, (2004) 14 Felipe, E., Mitic, D., and Zein, S. R., "Safety Benefits of Additional Primary Signal Heads." Vancouver, B.C., In

Columbia; G.D. Hamilton Associates, (1998) 

15 Gan, A., Shen, J., and Rodriguez, A., "Update of Florida Crash Reduction Factors and Countermeasures to Im

District Safety Improvement Projects." Florida Department of Transportation, (2005) 

16 Garder, P. and Davies, M., "Safety Effect of Continuous Shoulder Rumble Strips on Rural Interstates in Maine

Meeting: Compendium of Papers CD-ROM, Vol. TRB#06-2219, Washington, D.C., (2006) 
September 2007 

17 Gates, T. J., Noyce, D. A., Talada, V., and Hill, L., "The Safety and Operational Effects of "Road Diet" Convers

86th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#07-1918, Washington, D.C., (2007) 

18 Griffin, L. I. and Reinhardt, R. N., "A Review of Two Innovative Pavement Patterns that Have Been Developed 

Crashes." Washington, D.C., AAA Foundation for Traffic Safety, (1996) 

19 Griffith, M. S., "Safety Evaluation of Rolled-In Continuous Shoulder Rumble Strips Installed on Freeways." Tra

1665, Washington, D.C., Transportation Research Board, National Research Council, (1999) pp. 28-33. 

20 Gross, F. and Jovanis, P. P., "Estimation of Safety Effectiveness of Changes in Shoulder Width using Case-Co

2007 TRB 86th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#07-2762, Washington, D.C., (20

21 Harkey, D., Srinivasan, R., Zegeer, C., Persaud, B., Lyon, C., Eccles, K., Council, F. M., and McGee, H., "Cras

Engineering and Intelligent Transportation System (ITS) Improvements: State of Knowledge Report." Research 

Transportation Research Board of the National Academies, (2005) 

22 Harwood, D. W., Bauer, K. M., Potts, I. B., Torbic, D. J., Richard, K. R., Kohlman Rabbani, E. R., Hauer, E., an

Effectiveness of Intersection Left- and Right-Turn Lanes." FHWA-RD-02-089, McLean, Va., Federal Highway A

23 Harwood, D. W., Council, F. M., Hauer, E., Hughes, W. E., and Vogt, A., "Prediction of the Expected Safety Pe

Highways." FHWA-RD-99-207, McLean, Va., Federal Highway Administration, (2000) 

24 Harwood, D. W., Pietrucha, M. T., Wooldridge, M. D., Brydia, R. E., and Fitzpatrick, K., "NCHRP Report 375: M

Washington, D.C., Transportation Research Board, National Research Council, (1995) 

25 Hauer, E., "Left Turn Protection, Safety, Delay and Guidelines: A Literature Review", (2004), www.roadsafetyr26 Hirasawa, M., Takuda, T., Asano, M., and Saito, K., "Developing Optimal Centerline Rumble Strips and Evalua

National Highways in Hokkaido, Japan." 2006 TRB 85th Annual Meeting: Compendium of Papers CD-ROM, VD.C. , (2006) 

27 Hovey, P. W. and Chowdhury, M., "Development of Crash Reduction Factors." 14801(0), Ohio Department of 

28 Institute of Transportation Engineers, "Toolbox of Countermeasures and Their Potential Effectiveness to Make 

Sheet 8, ITE, FHWA, (2004) 

29 Lee, J. C., Wortman, R. H., Hook, D. J., and Poppe, M. J., "Comparative Analysis of Leading and Lagging Left 

Department of Transportation, (1991) 

30 Lovell, J. and Hauer, E., "The Safety Effect of Conversion to All-Way Stop Control." Transportation Research R

Transportation Research Board, National Research Council, (1986) pp. 103-107. 

31 Lyon, C, Haq, A., Persaud, B. N., and Kodama, S. T. , "Development of Safety Performance Functions for Sign

Urban Area and Application to Evaluation of Left Turn Priority Treatment." 2005 TRB 84th Annual Meeting: Co

Vol. TRB#05-2192, Washington, D.C., (2005) 
September 2007 

32 Markowitz, F., Sciortino, S., Fleck, J. L., and Yee, B. M., "Pedestrian Countdown Signals: Experience with an E

Institute of Transportation Engineers Journal, Vol. January 2006, ITE, (1-1-2006) pp. 43-48. Updated by Memochanges 2002-2004 and countdown signals,” (February 7th, 2006) 

33 McGee, H. W. and Blankenship, M. R., "NCHRP Report 320: Guidelines for Converting Stop to Yield Control a

D.C., Transportation Research Board, National Research Council, (1989) 

34 McGee, H., Taori, S., and Persaud, B. N., "NCHRP Report 491: Crash Experience Warrant for Traffic Signals.

Transportation Research Board, National Research Council, (2003) 

35 McGee, H., W., FHWA and Institute of Transportation Engineers, "Making Intersections Safer: A Toolbox of En

Reduce Red-Light Running." FHWA/TX-03/4027-2, Texas Transportation Institute, (2002) 

36 McMahon, P., Zegeer, C., Duncan, C., Knoblauch, R., Stewart, R., and Khattak, A., "An Analysis of Factors Co

Roadway' Crashes: Research Study and Guidelines for Sidewalks and Walkways," FHWA-RD-01-101, (2002) 

37 Miller, J. S., Khandelwal, R, and Garber, N. J., "Safety Impacts of Photo-Red Enforcement at Suburban Signal

Bayes Approach.", Transportation Research Record, No. 1969, Washington, D.C., Transportation Research Bo

Council, (2006), pp. 27-34. 

38 Montella, A., "Safety Reviews of Existing Roads: a Quantitative Safety Assessment Methodology." Vol. TRB#0

2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, (2005) 

39 Morena, D. A., Wainwright, W. S., and Ranck, F., "Older Drivers at a Crossroads." Public Roads, Vol. 70, No. 

(2007) pp. 6-15. 

40 Parker, M. R. Jr., “Effects of Raising and Lowering Speed Limits on Selected Roadway Sections.” FHWA-RD-941 Patel, R. B., Council, F. M., and Griffith, M. S., "Estimating the Safety Benefits of Shoulder Rumble Strips on T

Minnesota: An Empirical Bayes Observational Before-After Study." 2007 TRB 86th Annual Meeting: CompendTRB#07-1924, Washington, D.C. , (2007) 

42 Pawlovich, M. D., Li, W., Carriquiry, A., and Welch, T., "Iowa's Experience with "Road Diet" Measures: Impacts 

Crash Rates Assessed Following a Bayesian Approach." 2006 TRB 85th Annual Meeting: Compendium of Pap

2484, Washington, D.C., (2006) 

43 Pernia, J.C., Lu, J.J., Weng, M.X., Xie, X., and Yu, Z., “Development of Models to Quantify the Impacts of Sign

Crashes.” Florida Department of Transportation, (2002). 

44 Persaud, B. N., Retting, R. A., Garder, P. E., and Lord, D., " Safety Effect of Roundabout Conversions in the U

Observational Before-After Study." Transportation Research Record, No. 1751, Washington, D.C., Transportat

Research Council, (2001) pp.1–8. 

45 Persaud, B., Council, F. M., Lyon, C., Eccles, K., and Griffith, M., "Multi-Jurisdictional Safety Evaluation of Red 

Transportation Research Record, No. 1922, Washington, D.C., Transportation Research Board, National Rese

37.
September 2007 

46 Persaud, B., Hauer, E., Retting, R. A., Vallurupalli, R., and Mucsi, K., "Crash Reductions Related to Traffic Sig

Accident Analysis and Prevention, Vol. 29, No. 6, Oxford, N.Y., Pergamon Press, (1997) pp. 803-810. 

47 Polanis, S. F., "Low-Cost Safety Improvements." Chapter 27, The Traffic Safety Toolbox: a primer on traffic sa

Institution of Transportation Engineers, (1999) pp. 265-272. 

48 Preston, H. and Schoenecker, T., "Bypass Lane Safety, Operations, and Design Study" MN/RC-2000-14, St. P

Transportation, (1999) 

49 Retting, R. A., Chapline, J. F., and Williams, A. F., "Changes in Crash Risk Following Re-timing of Traffic Sign

Analysis and Prevention, Vol. 34, No. 2, Oxford, N.Y., Pergamon Press, (2002) pp. 215-220. 

50 Rodegerdts, L. A., Blogg, M., Wemple, E., Myers, E., Kyte, M., Dixon, M., List, G., Flannery, A., Troutbeck, R., 

B., Lyon, C., Harkey, D., and Carter, E. C., "Roundabouts in the United States." NCHRP Report 572, Washingt

Research Board of the National Academies, (2007) 

51 Rodegerdts, L. A., Nevers, B., and Robinson, B., "Signalized Intersections: Informational Guide." FHWA-HRT-

52 Sayed, T., El Esawey, M., and Pump, J., "Evaluating the Safety Impacts of Improving Signal Visibility at Urban 

TRB 86th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#07-135, Washington, D.C., (2007) 

53 Sayed, T., El-Basyouny, K., and Pump, J., "Safety Evaluation of Stop Sign In-Fill Program." Transportation Re

Washington, D.C., Transportation Research Board, National Research Council, (2006) pp. 201-210. 

54 Sayed, T., Leur, P., and Pump, J., "Safety Impact of Increased Traffic Signal Backboards Conspicuity." 2005 T

Compendium of Papers CD-ROM, Vol. TRB#05-16, Washington, D.C., (2005) 

55 Schoon, C. and van Minnen, J., "The Safety of Roundabouts in The Netherlands." Traffic Engineering & Contr

United Kingdom, Hemming Information Services, (1994) pp. 142-148. 

56 Shin, K. and Washington, S., "The Impact of Red Light Cameras on Safety in Arizona." 2006 TRB 85th Annua

Papers CD-ROM, Vol. TRB#06-1514, Washington, D.C., (2006) 

57 Smith, E. B. and Ivan, J. N., "Evaluation of Safety Benefits and Potential Crash Migration Due to Shoulder Rum

Freeways in Connecticut." 2005 TRB 84th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#05-12

58 Turner, B., "Crash reduction estimates for road safety treatments.", Vermont, Australia, ARRB Group, (2007) 59 Xu, L., "Right Turns Followed by U-Turns versus Direct Left Turns: A Comparison of Safety Issues." ITE Journ

D.C., Institute of Transportation Engineers, (2001) pp. 36-43. 

60 Zegeer, C., Stewart, R., Huang, H., and Lagerwey, P., "Safety Effects of Marked vs. Unmarked Crosswalks at 

Executive Summary and Recommended Guidelines," FHWA-RD-01-075, (2002). 

61 Zimmerman, K. and Bonneson, J., “In-Service Evaluation of the Detection-Control System for Isolated High-Sp

85th Annual Meeting: Compendium of Papers CD-ROM, Vol. TRB#06-1252, Washington, D.C., (2006) 
Report No. FHWA-SA-07-015 

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