1

This chart summarizes studies about the effectiveness of engineering countermeasures. Studies where an increase in crashes were reported are also shown since this 

information is also relevant in selection of countermeasures.

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

Vertical Deflections Within the Roadway

Speed Hump—rounded, raised 

area placed across the roadway, 

typically 12 to 14 feet long

pedestrian urban — 100 (2009) 6 — all — — -48% CA -43% change in 

average volume

pedestrian urban — 100 (2009) 5 — all — — 3% FL -28% change in 

average volume

pedestrian urban — 100 (2009) 16 — all — — -46% MD -32% change in 

average volume

pedestrian urban — 100 (2009) 20 — all — — -33% NE volume change 

unknown

pedestrian urban — 100 (2009) 4 — all — — -46% OH -29% change in 

average volume

pedestrian urban — 100 (2009) 5 — all — — -40% OR -20% change in 

average volume

Speed Table—a long speed 

hump typically 22 feet in length 

with a flat section in the middle 

and ramps on the ends

pedestrian urban residential 6 (2003) 19 2-3 yrs./2-3 yrs. total — — -38% GA

pedestrian urban residential 6 (2003) 19 2-3 yrs./2-3 yrs. injury — — -93% GA

pedestrian urban — 100 (2009) 4 — all — — -64% MD -15% change in 

average volume

pedestrian urban — 100 (2009) 4 — all — — -36% OR

-20% change in average volume

Engineering Speed Management Countermeasures: 

A Desktop Reference of Potential Effectiveness in Reducing Crashes

July 2014

http://safety.fhwa.dot.gov
2

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

Speed Cushion—raised area 

that allows most emergency 

vehicles to straddle the hump

pedestrian no crash studies found for speed cushions

Raised Intersection—a 

raised plateau, with ramps on 

all approaches, where roads 

intersect 

pedestrian — — 69 (2004) — — serious/ 

minor injury 1.05 — —

Horizontal Deflections/Roadway Narrowing

Choker/Bulb-out—mid-block 

curb extensions that narrow 

road by extending the sidewalk 

or widening the planting strip 

pedestrian no crash studies found for chokers

Neck Down—intersection curb 

extensions that narrow a road 

by extending the width of a 

sidewalk 

pedestrian no crash studies found for neck-downs

Chicanes—curb extensions 

that alternate from one side of 

the street to the other forming 

S-shaped curves

pedestrian no crash studies found for chicanes

Center Island—raised or 

painted island along the 

centerline that narrows travel 

lanes 

pedestrian — — 70 (2011) — — all 0.61 — UT raised median

pedestrian — — 70 (2011) — — fatal/ 

serious 0.56 — UT raised median

pedestrian urban principal 

arterial 71 (2008) — — all 0.29 — UT raised median

pedestrian urban principal 

arterial 71 (2008) — — angle 0.45 — UT raised median

pedestrian urban principal 

arterial 72 (2010) — — all 0.86 — NJ raised median

pedestrian urban principal 

arterial 69 (2004) — — serious/ minor 0.78 — — raised median

pedestrian urban principal 

arterial 69 (2004) — — PDO 1.09 — — raised median

pedestrian rural principal 

arterial 69 (2004) — — serious/minor 0.88 — — raised median

pedestrian rural principal 

arterial 69 (2004) — — PDO 0.82 — — raised median

pedestrian urban — 69 (2004) — — fatal/serious/ minor 0.61 — — raised median

pedestrian rural — 69 (2004) — — PDO 2.28 — — raised median

pedestrian rural — 69 (2004) — —

fatal/

serious/ 

minor

1.94 — — raised median
3

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Center Island—raised 

or painted island along the 

centerline that narrows travel 

lanes

pedestrian

urban/ 

suburban

principal 

arterial 73 (2002) — — vehicle/ped 0.61 —

WA, OR, 

CA, AZ, 

UT, KS, 

TX, MO, 

Wi, OH, 

PA, MA, 

MD, NC, 

FL

raised median + 

unmarked crosswalk

pedestrian

urban/ 

suburban

principal 

arterial 73 (2002) — — vehicle/ped 0.54 —

WA, OR, 

CA, AZ, 

UT, KS, 

TX, MO, 

Wi, OH, 

PA, MA, 

MD, NC, 

FL

raised median + 

marked crosswalk

pedestrian rural

stop-controlled 

intersection

74 (2008) — — all 0.69 — PA, KY, 

MO

lane narrowing + 

painted median + 

rumble strips

pedestrian rural

stop-controlled 

intersection

74 (2008) — — fatal/serious/ minor 0.80 — PA, KY, 

MO

lane narrowing + 

painted median + 

rumble strips

pedestrian rural

stop-controlled 

intersection

74 (2008) — — angle 0.58 — PA, KY, 

MO

lane narrowing + 

painted median + 

rumble strips

pedestrian rural

stop-controlled 

intersection

74 (2008) — — rear-end 1.54 — PA, KY, 

MO

lane narrowing + 

painted median + 

rumble strips

Reduce Lane Width with 

Markings—narrowing of 

the lanes using pavement 

markings, median, etc. 

roadway 

departure rural — 69 (2004) — — injury 1.05 — — 8 inch edge line

Road Diet—reducing 

the number of lanes by 

reallocating roadway space 

for other uses (e.g. bike lanes, 

center turn lanes, medians, 

parking, shoulder lanes, etc.

pedestrian urban 3-lane 75 (2003) 1 20 mon/ 20 

mon

all — — 62% MT 4- to 3-lane

pedestrian urban 3-lane 75 (2003) 1 — all — — -28% MN 4- to 3-lane

pedestrian urban 3-lane 75 (2003) 1 1 yrs./1 yrs. all — — -17% CA 4- to 3-lane

pedestrian urban 3-lane 75 (2003) 1 1 yrs./1 yrs. all — — -17% CA 4- to 3-lane

pedestrian urban 3-lane 75 (2003) 1 2 yrs./2 yrs. all — — -52% CA 4- to 3-lane

pedestrian urban 3-lane 75 (2003) 9 1 yrs./1 yrs. all — — -34% WA 4- to 3-lane

pedestrian urban 3-lane 75 (2003) 9 1 yrs./1 yrs. all — — -57% IA 4- to 3-lane

pedestrian suburban 3-lane 76 (2010)

30 treatment/ 51 

control

17.5 yrs./4.5 yrs. all 0.81 — — CA, WA 4- to 3-lane
4

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Road Diet—reducing 

the number of lanes by 

reallocating roadway space 

for other uses (e.g. bike lanes, 

center turn lanes, medians, 

parking, shoulder lanes, etc.

pedestrian small 

urban 3-lane 76 (2010)

15 treatment/ 

296 

control

4.7 yrs./3.5 yrs. all 0.53 — — IA 4- to 3-lane

pedestrian urban 3-lane 77 (2007) — — all 0.67 — — MN 4- to 3-lane

pedestrian urban 3-lane 77 (2007) — — injury 1.00 — — MN 4- to 3-lane

pedestrian urban 3-lane 77 (2007) — — PDO 0.54 — — MN 4- to 3-lane

pedestrian urban 3-lane 77 (2007) — — angle 0.76 — — MN 4- to 3-lane

pedestrian urban 3-lane 78 (2012) — — all 0.95 — MI 4- to 3-lane

pedestrian urban 3-lane 79 (2006)

15 treatment 

/ 15 

control

11 to 21 yrs./1 

to 11 yrs. all — — -25% IA 4- to 3-lane

pedestrian urban 3-lane minor arterial 80 (2008) — — all 0.71 — — 4- to 3-lane

pedestrian urban 3-lane 

arterial 78 (2012) — 3 yrs./3 yrs. all 0.91 — — MI 4- to 3-lane

pedestrian urban 3-lane 

arterial 78 (2012) — 3 yrs./3 yrs. not specified 0.59 — — MI 4- to 3-lane

Surface Treatments and Markings

Transverse Rumble Strips— 

raised or grooved patterns 

installed on the roadway travel 

lane or shoulder pavements 

perpendicular to the direction 

of travel  

roadway 

departure

urban/ 

suburbanlocal 69 (2004) — — all 0.66 — —

roadway 

departure

urban/ 

suburbanlocal 69 (2004) — — serious/

minor 0.64 — —

roadway 

departure

urban/ 

suburbanlocal 69 (2004) — — PDO 0.73 — —

roadway 

departure rural

minor arterial at stop 

control

81 (2010) — — all 1.2 — MN, IA

roadway 

departure rural

major 

collector 

at stop 

control

81 (2010) — — all 0.67 to 

1.4 — MN, IA

roadway 

departure rural

major 

collector 

at stop 

control

81 (2010) — — fatal/serious/ minor 0.91 — MN, IA

roadway 

departure rural

major 

collector 

at stop 

control

81 (2010) — — fatal/serious 0.75 — MN, IA
5

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Transverse Rumble 

Strips—raised or grooved 

patterns installed on the 

roadway travel lane or shoulder 

pavements perpendicular to 

the direction of travel

roadway 

departure rural

major 

collector 

at stop 

control

81 (2010) — — PDO 1.20 — MN, IA

pedestrian rural low-volume 82 (2011) — — all 0.76 — China at pedestrian crosswalk

roadway 

departure rural curve 69 (2004) — — ROR serious/minor 0.94 — — with RPMs

roadway 

departure rural — 83 (1986) — — all 0.47 — KY with RPMs

roadway 

departure rural — 83 (1986) — — wet road 0.51 — KY with RPMs

roadway 

departure rural — 83 (1986) — — nighttime 0.36 — KY with RPMs

roadway 

departure rural — 83 (1986) — — all 1.10 — KY with RPMs + transverse markings

roadway 

departure rural — 83 (1986) — — wet road 0.91 — KY with RPMs + transverse markings

roadway 

departure rural — 83 (1986) — — nighttime 0.83 — KY with RPMs + transverse markings

Transverse Markings—

pavement markings placed 

across the lane perpendicular to 

direction of travel

roadway 

departure rural

freeway to 

freeway 

connector

36 (2003) 1 2 yrs./2 yrs. — — — -48% WI converging chevrons

roadway 

departure urban — 84 (1996) — — all 0.68 — — converging chevrons

roadway 

departure no crash studies found for optical speed bars, herringbone, dragon’s teeth, or transverse bars

Pavement Marking Legends— 

speed limit or other onpavement signing

roadway 

departure no crash studies found for any type of pavement marking legends

In-roadway Warning Lights roadway 

departure rural interstate (4-lane) 45 (1977) 1 9 mon/9 mon

crashes 

under foggy 

conditions

— — -75% VA

Vertical Delineation

Vertical Treatments—vertical 

objects such as post mounted 

delineators which are placed 

along the roadway to provide 

better delineation and/or 

provide a feeling of friction

roadway 

departure rural curve 85 (2006) — — ROR — — -15% OH post mounted delineator

roadway 

departure rural — 69 (2004) — — injury 1.04 — — — post mounted delineator

roadway 

departure rural curve 86 (2008); 87 (2005) — — total 0.70 to 0.80 — — — post mounted delineator

roadway 

departure rural curve (4-lane) 88 (2009) 4 — total — — -47% Italy

sequential flashing 

beacons + chevrons 

+ curve warning 

signs
6

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Vertical Treatments—

vertical objects such as post 

mounted delineators which are 

placed along the roadway to 

provide better delineation and/

or provide a feeling of friction

roadway 

departure rural curve (4-lane) 88 (2009) 4 — nighttime — — -76% Italy

sequential flashing 

beacons + chevrons 

+ curve warning 

signs

roadway 

departure rural curve (4-lane) 88 (2009) 4 — ROR — — -47% Italy

sequential flashing 

beacons + chevrons 

+ curve warning 

signs

roadway 

departure rural curve (4-lane) 88 (2009) 4 — rainy — — -42% Italy

sequential flashing 

beacons + chevrons 

+ curve warning 

signs

roadway 

departure rural curve (4-lane) 88 (2009) 4 — injury — — -37% Italy

sequential flashing 

beacons + chevrons 

+ curve warning 

signs

roadway 

departure no crash studies found for reflective post treatment, streaming PMDs

Landscaping—roadside 

plantings used to create vertical 

friction

roadway 

departure urban collector 48 (2000) 1 31 mon/17 mon all no change — — — landscaped median and curbside islands

Gateway Entrance Treatments

Gateway Treatment—placed 

at community entrance to 

remind drivers of changing 

roadway character

pedestrian rural community 

entrance 89 (2009) 7 3-9 yrs./2-7 yrs. — — — -2% & -32% CA 3400 to 27500 vpdgateway monument

pedestrian no crash studies found for pavement marking gateways or combination of entrance treatments

Dynamic Signing

Dynamic Speed Feed-back 

Signs—displays message 

for drivers traveling over the 

threshold speed

roadway 

departure rural curve (2-lane) 59 (2002) 2 — injury — — -54 to -100%

United 

Kingdom

“SLOW DOWN” + 

curve warning

roadway 

departure rural interstate 61 (2000) 5 5-yrs./6-mon all — — -2% CA “50 MPH CURVES” + “YOUR SPEED XX”

roadway 

departure rural curve (2-lane) 57 (2013) 22 3-yrs./ 2-yrs. all 0.93 to 0.95 — —

IA, FL, 

WA, AZ, 

OR, OH, 

TX

“YOUR SPEED XX” + 

curve advisory sign

roadway 

departure rural curve (2-lane) 57 (2013) 22 3-yrs./ 2-yrs. single vehicle 0.95 — —

IA, FL, 

WA, AZ, 

OR, OH, 

TX

“YOUR SPEED XX” + 

curve advisory sign

roadway 

departure no crash studies found for flashing beacons
7

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

Intersection Treatments

Roundabout—large, raised, 

circular islands at the middle 

of major intersections, around 

which all oncoming vehicles 

must traverse

intersection — — 90 (1994) 181 — injury 0.35 — Netherlands

intersection — — 90 (1994) 181 — PDO 0.58 — Netherlands

intersection all — 90 (1994) 181 — vehicle/ped 0.27 — Netherlands

intersection all — 90 (1994) 181 — vehicle/ped 0.27 — Netherlands

intersection all urban/

rural 91 (2013) 13 3 yrs./3 yrs. fatal/injury 0.47 — WI low speed roundabout

intersection all urban/

rural 91 (2013) 11 3 yrs./3 yrs. all 0.66 — WI high speed roundabout

intersection all urban/

rural 91 (2013) 11 3 yrs./3 yrs. fatal/injury 0.51 — WI high speed roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs. all 0.33 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs. injury 0.13 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs. fatal/injury 0.11 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs. angle 0.17 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs. rear-end 0.85 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs. injury angle 0.09 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs. sideswipe 2.79 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs. fixed object 4.66 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs.

frontal/ 

opposing 

direction/ 

sideswipe

2.40 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout

intersection rural rural 92 (2012) 19 98 data yrs./98 

data yrs.

rear-end 

injury 0.54 —

MD, WA, 

KS, WI, 

MN, OR

high-speed 

roundabout
8

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Roundabout—large, 

raised, circular islands at the 

middle of major intersections, 

around which all oncoming 

vehicles must traverse

intersection all urban/

rural 91 (2013) 13 3 yrs./ 3 yrs. all 1.10 — WI low speed roundabout

intersection rural one-way 

stop 92 (2012) 2 98 data yrs./98 data yrs. all 0.74 — OR, KS 3-leg to roundabout

intersection rural one-way 

stop 92 (2012) 2 98 data yrs./98 data yrs. injury 0.28 — OR, KS 3-leg to roundabout

intersection all urban/

rural 91 (2013) 2 3 yrs./3 yrs. all 1.24 — WI no control/yield to roundabout

intersection all urban/

rural 91 (2013) 12 3 yrs./3 yrs. all 1.10 — WI multi-lane roundabout

intersection all urban/

rural 91 (2013) 12 3 yrs./3 yrs. fatal/injury 0.37 — WI multi-lane roundabout

intersection all urban/

rural 91 (2013) 12 3 yrs./3 yrs. all 0.64 — WI single-lane roundabout

intersection all urban/

rural 91 (2013) 12 3 yrs./3 yrs. fatal/injury 0.82 — WI single-lane roundabout

intersection urban — 93 (2001) 9 2 to 5 yrs./1.3 to 

5.3 yrs. all 0.95 —

CO, FL, 

KS, ME, 

MD, SC, 

VT

stop-control to multilane roundabout

intersection urban — 93 (2001) 14 2 to 5 yrs./1.3 to 

5.3 yrs. all 0.28 —

CO, FL, 

KS, ME, 

MD, SC, 

VT

stop-control 

to single-lane 

roundabout

intersection urban — 93 (2001) 14 2 to 5 yrs./1.3 to 

5.3 yrs. injury 0.12 —

CO, FL, 

KS, ME, 

MD, SC, 

VT

stop-control 

to single-lane 

roundabout

intersection urban — 93 (2001) 14 2 to 5 yrs./1.3 to 

5.3 yrs. all 0.42 —

CO, FL, 

KS, ME, 

MD, SC, 

VT

stop-control 

to single-lane 

roundabout

intersection urban — 93 (2001) 14 2 to 5 yrs./1.3 to 

5.3 yrs. injury 0.18 —

CO, FL, 

KS, ME, 

MD, SC, 

VT

stop-control 

to single-lane 

roundabout

intersection all urban/

rural 91 (2013) 5 3 yrs./3 yrs. all 1.11 — WI all-way stop-control to roundabout

intersection all urban/

rural 91 (2013) 5 3 yrs./3 yrs. fatal/injury 0.54 — WI all-way stop-control to roundabout

intersection all all 94 (2007) 10 3.7 yrs./3.3 yrs. all 1.03 —

FL, MS, 

MO, NV, 

OR, WA

all-way stop-control 

to roundabout

intersection all urban/

rural 91 (2013) 12 3 yrs./3 yrs. all 0.75 — WI two-way stop-control to roundabout
9

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Roundabout—large, 

raised, circular islands at the 

middle of major intersections, 

around which all oncoming 

vehicles must traverse

intersection all urban/

rural 91 (2013) 12 3 yrs./3 yrs. fatal/injury 0.65 — WI two-way stop-control to roundabout

Intersection all multi-lane/

single-lane 94 (2007) 36 3.7 yrs./3.3 yrs. all 0.56 —

CO, FL, 

KS, MD, 

ME, NV, 

OR, VT, 

WA, WI

minor stop-control to 

roundabout

intersection all multi-lane/

single-lane 94 (2007) 36 3.7 yrs./3.3 yrs. injury 0.18 —

CO, FL, 

KS, MD, 

ME, NV, 

OR, VT, 

WA, WI

minor stop-control to 

roundabout

intersection rural single-lane 94 (2007) 9 3.7 yrs./3.3 yrs. all 0.29 — KS; MD minor stop-control to 

roundabout

intersection rural single-lane 94 (2007) 9 3.7 yrs./3.3 yrs. injury 0.13 — KS; MD minor stop-control to 

roundabout

intersection urban multi-lane/

single-lane 94 (2007) 17 3.7 yrs./3.3 yrs. all 0.61 to 0.88 —

FL, KS, 

MD, ME, 

NV, OR, 

VT, WA, 

WI

minor stop-control to 

roundabout

intersection urban multi-lane/

single-lane 94 (2007) 17 3.7 yrs./3.3 yrs. injury 0.19 to 0.22 —

FL, KS, 

MD, ME, 

NV, OR, 

VT, WA, 

WI

minor stop-control to 

roundabout

intersection suburban

multi-lane/

single-lane 94 (2007) 10 3.7 yrs./3.3 yrs. all 0.22 to 0.81 — CO, KS, MD, WA

minor stop-control to 

roundabout

intersection suburban

multi-lane/

single-lane 94 (2007) 10 3.7 yrs./3.3 yrs. injury 0.22 to 0.29 — CO, KS, MD, WA

minor stop-control to 

roundabout

intersection — — 95 (2007) 62 3 yrs./1 yrs. injury 0.56 — Belgium unsignalized to 

roundabout

intersection — — 95 (2007) 62 3 yrs./1 yrs. minor injury 0.54 — Belgium unsignalized to 

roundabout

intersection — — 95 (2007) 62 3 yrs./1 yrs. serious 

injury 0.80 — Belgium unsignalized to roundabout

intersection

urban/ 

suburban

2-lane 

urban/suburban96 (2013) 16 3.9 yrs./3.1 yrs. all 0.81 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 2-lane 

roundabout

intersection

urban/ 

suburban

2-lane 

urban/ 

suburban

96 (2013) 16 3.9 yrs./3.1 yrs. injury 0.29 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 2-lane 

roundabout
10

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Roundabout—large, 

raised, circular islands at the 

middle of major intersections, 

around which all oncoming 

vehicles must traverse

intersection

urban/ 

suburban

1-lane 

urban/ 

suburban

96 (2013) 12 3.9 yrs./3.1 yrs. all 0.74 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to singlelane roundabout

intersection all urban/

rural 91 (2013) 5 3 yrs./3 yrs. all 0.96 — WI

signalized to 

single- or multi-lane 

roundabout

intersection urban urban/

rural 91 (2013) 5 3 yrs./3 yrs. all 0.65 — WI

signalized to 

single- or multi-lane 

roundabout

intersection urban urban/

rural 91 (2013) 5 3 yrs./3 yrs. injury 0.26 — WI

signalized to 

single- or multi-lane 

roundabout

intersection

urban/ 

suburban

2-lane/1-

lane 96 (2013) 28 3.9 yrs./3.1 yrs. injury 0.45 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

single- or multi-lane 

roundabout

intersection all urban/

rural 91 (2013) 5 3 yrs./3 yrs. fatal/injury 0.35 — WI

signalized to 

single- or multi-lane 

roundabout

intersection — — 95 (2007) 33 3 yrs./1 yrs. injury 0.68 — Belgium signalized to 

roundabout

intersection — — 95 (2007) 33 3 yrs./1 yrs. major injury 0.87 — Belgium signalized to 

roundabout

intersection — — 95 (2007) 33 3 yrs./1 yrs. minor injury 0.69 — Belgium signalized to 

roundabout

intersection all

2-lane/1-

lane: 

(urban/

suburban)

96 (2013) 28 3.9 yrs./3.1 yrs. all 0.52 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection all

2-lane/1-

lane: 

(urban/

suburban)

96 (2013) 28 3.9 yrs./3.1 yrs. injury 0.22 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection

urban/ 

suburban

2-lane/1-

lane

96 (2012); 

94 (2007); 

97 (2011)

13/5/13 3.9 yrs./3.1 yrs. all 0.99 to 

1.15 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection urban multi-lane/

single-lane 94 (2007) 5 3.7 yrs./ 3.3 yrs. injury 0.40 — FL, MD, MI, SC

signalized to 

roundabout
11

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Roundabout—large, 

raised, circular islands at the 

middle of major intersections, 

around which all oncoming 

vehicles must traverse

intersection urban

2-lane/

1-lane: 

(urban)

96 (2013) 13 3.9 yrs./3.1 yrs. injury 0.45 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection urban urban 97 (2011) 13 3.9 yrs./3.1 yrs. fatal/injury 0.44 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection

urban/ 

suburban

2-lane/

1-lane

96 (2012); 

97 (2011) 28/ 28 3.9 yrs./3.1 yrs. injury 0.34 to 0.37 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection

urban/ 

suburban

2-lane/

1-lane 96 (2012) 28 3.9 yrs./3.1 yrs. fatal/injury 0.28 to 0.45 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection suburban

multi-lane/ 

2-lane/

1-lane/

suburban 

(2-lane: 8, 

1-lane: 7)

94 (2007); 

96 (2013); 

97 (2011)

4/ 15/ 15 3.7 yrs./ 3.3 yrs. all 0.33 to 

0.58 —

CO and 

VT/ CO, 

FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection suburban

2-lane/

1-lane 96 (2013) 15 3.9 yrs./3.1 yrs. injury 0.26 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection suburban suburban 97 (2011) 15 3.9 yrs./3.1 yrs. fatal/injury 0.26 —

CO, FL, IN, 

MD, MI, 

NY, NC, 

SC, VT, 

WA

signalized to 

roundabout

intersection rural

interchange off 

ramp/on 

ramp

98 (2012) 1 30 mon/ 6 mon all 0.63 — MS signalized to 

roundabout

intersection rural

interchange off 

ramp/on 

ramp

98 (2012) 1 30 mon/ 6 mon injury 0.40 — MS signalized to 

roundabout
12

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

Signing

Chevron Signs—use of 

standard chevron signing

roadway 

departure rural

principal 

arterial/ 

freeways/ 

expressways

88 (2009) 15 — all crashes 0.59 — Italy with curve warning 

sign

roadway 

departure rural

principal 

arterial/

freeways/ 

expressways

88 (2009) 15 — ROR crashes 0.56 — Italy with curve warning 

sign

roadway 

departure rural 2-lane 88 (2009) 15 —

fatal/serious 

injury/minor injury1.46 — Italy with curve warning 

sign

roadway 

departure rural 2-lane 88 (2009) 15 — nighttime 0.66 — Italy with curve warning sign

roadway 

departure rural

principal 

arterial/

freeways/ 

expressways

88 (2009); 

99 (2009) — — all crashes on

0.63 to 

1.27 — CA, WA; Italy

roadway 

departure rural

principal 

arterial/

freeways/ 

expressways

88 (2009); 

99 (2009) — — ROR crashes 0.9 — CA, WA; Italy

roadway 

departure rural

on 

principal 

arterial/

freeways/ 

expressways

88 (2009); 

99 (2009) — — property damage 0.83 — CA, WA; Italy

roadway 

departure rural

principal 

arterial/

freeways/ 

expressways

88 (2009); 

99 (2009) — — fatal and injury crashes 1.46 — CA, WA; Italy

roadway 

departure rural

principal 

arterial/

freeways/ 

expressways

88 (2009); 

99 (2009) — — nighttime 1.92 — CA, WA; Italy

roadway 

departure rural

principal 

arterial/

freeways/ 

expressways

88 (2009); 

99 (2009) — — wet road crashes on 0.41 — CA, WA; Italy
13

Category Safety 

Focus Area Roadway Reference Sites Study Period (before/after)

Crash 

Type CMF

CMF 

Clearinghouse 

Star Rating

Crash 

Reduction Location Notes

(cont’d) Chevron Signs—use of 

standard chevron signing

roadway 

departure rural 2-lane 88 (2009); 99 (2009) — — all crashes 0.96 — CA, WA; Italy

roadway 

departure rural 2-lane 88 (2009); 99 (2009) — — head-on/sideswipe 0.94 — CA, WA; Italy

roadway 

departure rural 2-lane 88 (2009); 99 (2009) — — fatal and injury 0.84 — CA, WA; Italy

roadway 

departure rural 2-lane 88 (2009); 99 (2009) — — nighttime 0.75 — CA, WA; Italy

roadway 

departure rural 2-lane 88 (2009); 99 (2009) — —

nighttime 

head-on/

sideswipe

0.78 — CA, WA; 

Italy

Access Control

Closure/Diversions—road 

closings or diversion of traffic

roadway 

departure no crash studies found for half-closure

roadway 

departure no crash studies found for diagonal diverters

roadway 

departure no crash studies found for full closure

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Abbreviations

common state destinations are used and are not listed here (e.g. Iowa = IA)

advisory (adv)

intersection (isect)

month (mon.)

pedestrian (ped)

post mounted delineator (PMD)

rumble strips (RS)

run off road (ROR)

years (yrs.)

http://safety.fhwa.dot.gov

FHWA-SA-14-100