U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
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. For the most current information on Crash Modification Factors (CMF), please go to the CMF Clearinghouse at: http://www.cmfclearinghouse.org.
| 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 | |
| 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 | |
| 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 | 0.8 | ★★ | – | 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 | |
| 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 | – | – | 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/ suburban | local | 69 (2004) | – | – | all | 0.66 | ★★★★ | – | – | |
| roadway departure | urban/ suburban | local | 69 (2004) | – | – | serious/minor | 0.64 | ★★★★ | – | – | |
|
| roadway departure | urban/ suburban | local | 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 | |
|
| roadway departure | rural | major collector at stop control | 81 (2010) | – | – | PDO | 1.2 | ★★★★ | – | 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 | 1.1 | ★ | – | 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 on-pavement 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 | |
| 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. | – | – | – | -0.02-0.32 | CA | 3400 to 27500 vpd gateway monument |
| pedestrian | no crash studies found for pavement marking gateways or combination of entrance treatments | – | – | – | – | – | – | – | – | – | |
|
| Dynamic Signing | ||||||||||||
| Dynamic Speed Feedback 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 | – | – | – | – | – | – | – | – | – | |
|
| 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 | 2.4 | ★★ | – | 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 | |
| intersection | all | urban/rural | 91 (2013) | 13 | 3 yrs./ 3 yrs. | all | 1.1 | ★★★★ | – | 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 | 1.1 | ★★★★ | – | 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) | 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 | |
| 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 | 0.8 | ★★★★ | – | Belgium | unsignalized to roundabout | |
| intersection | urban/ suburban | 2-lane urban/suburban | 96 (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 | |
| 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 single-lane 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 | 0.4 | ★★★★ | – | FL, MD, MI, SC | signalized to roundabout | |
| 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) | 4/15/2015 | 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 | 0.4 | ★★★ | – | MS | signalized to roundabout | |
| 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 injury | 1.46 | ★★★ | – | 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 | |
|
| 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 | – | – | – | – | – | – | – | – | – | |
|
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.)
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The crash modification factor warehouse can be accessed at: http://www.cmfclearinghouse.org
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