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FHWA Home / Safety / Speed Management / Engineering Speed Management Countermeasures

Engineering Speed Management Countermeasures

A Desktop Reference of Potential Effectiveness in Reducing Crashes

July 2014

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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 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.)

References

The crash modification factor warehouse can be accessed at:  http://www.cmfclearinghouse.org

1.   Ewing, R. 1999. Traffic Calming: State of the Practice. Institute of Transportation Engineers, Washington, DC.

2.  ACV.  Effectiveness of Traffic Calming Measures in Arlington County.  Arlington County, VA. 2005. 

3.  Marek, J.C. and Walgren, S.  "Mid-Block Speed Control: Chicanes and Speed Humps."  City of Seattle, WA. 2000. www.seattle.gov/Transportation/docs/ITErevfin.pdf

4.  Ponnaluri, R.V. and P.W. Groce.  "Operational Effectiveness of Speed Humps in Traffic Calming."  ITE Journal.  2005.  pp. 26-30.

5.  Smith, D., S. Hallmark, K. Knapp, and G. Thomas.  Temporary Speed Hump Impact Evaluation.  Center for Transportation Research and Education at Iowa State University.  July 2002.

6.  Bretherton, W.M. "Do Speed Tables Improve Safety."  Presented at the 2003 Annual Meeting of the Institute of Transportation Engineers.  August 2003, Seattle Washington.

7.  Hallmark, S.L, E. Peterson, E. Fitzsimmons, N. Hawkins, J. Resler, and T. Welch.  Evaluation of Gateway and Low-Cost Traffic-Calming Treatments for Major Routes in Small Rural Communities, Phase I. Center for Transportation Research and Education, Iowa State University. Ames, Iowa. November 2007.  www.intrans.iastate.edu/research/projects/detail/?projectID=-226410767

8.  Corkle, J., J.L. Giese, and M.M. Marti. 2001. Investigating the Effectiveness of Traffic Calming Strategies on Driver Behavior, Traffic Flow, and Speed. Minnesota Local Road Research Board, Minnesota Department of Transportation. October 2001.

9.  NYCDOT.  Downtown Brooklyn Traffic Calming Study.  New York City Department of Transportation.  2004.

10.  M. William.  "Evaluation of Speed Control Measures in Residential Areas."  Traffic Engineering, Institute of Transportation Engineers, Washington, DC.  March 1977.

11.  Molino, J.A., B.J. Katz, M.B. Hermosillo, E.E. Dagnall, and J.F. Kennedy.  Simulator Evaluation of Low-Cost Safety Improvements on Rural Two-Lane Undivided Roads:  Nighttime Delineation for Curves and Traffic Calming for Small Towns.  Science Applications International Corporation.  McLean, VA.  February 2010.

12.  Macbeth, A.G. 1998. "Calming arterials in Toronto."  Presented at the 1998 Annual Meeting of the Institute of Transportation Engineers.

13.  Kamyab, A., S. Andrle, and D. Kroeger.  Methods to Reduce Traffic Speeds at High Pedestrian Areas. Center for Transportation Research and Education. Ames, Iowa. March 2002. www.ctre.iastate.edu/research/detail.cfm?projectid=1052946660.

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