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                        Safety
                        Speed Management Safety

              Engineering Speed Management Countermeasures: A Desktop Reference of Potential Effectiveness in Reducing Crashes July 2014

eng_ctm_crsh_14.pdf (658.4 KB)

July 2014

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
			NotesVertical 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 volumepedestrian
			urban
			–
			100 (2009)
			5
			–
			all
			–
			–
			3%
			FL
			-28% change in average volumepedestrian
			urban
			–
			100 (2009)
			16
			–
			all
			–
			–
			-46%
			MD
			-32% change in average volumepedestrian
			urban
			–
			100 (2009)
			20
			–
			all
			–
			–
			-33%
			NE
			volume change unknownpedestrian
			urban
			–
			100 (2009)
			4
			–
			all
			–
			–
			-46%
			OH
			-29% change in average volumepedestrian
			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%
			GApedestrian
			urban
			residential
			6 (2003)
			19
			2-3 yrs./2-3 yrs.
			injury
			–
			–
			-93%
			GApedestrian
			urban
			–
			100 (2009)
			4
			–
			all
			–
			–
			-64%
			MD
			-15% change in average volumepedestrian
			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 medianpedestrian
			–
			–
			70 (2011)
			–
			–
			fatal/ serious
			0.56
			★★★★
			–
			UT
			raised medianpedestrian
			urban
			principal arterial
			71 (2008)
			–
			–
			all
			0.29
			★★★
			–
			UT
			raised medianpedestrian
			urban
			principal arterial
			71 (2008)
			–
			–
			angle
			0.45
			★★★
			–
			UT
			raised medianpedestrian
			urban
			principal arterial
			72 (2010)
			–
			–
			all
			0.86
			★★★
			–
			NJ
			raised medianpedestrian
			urban
			principal arterial
			69 (2004)
			–
			–
			serious/ minor
			0.78
			★★★★★
			–
			–
			raised medianpedestrian
			urban
			principal arterial
			69 (2004)
			–
			–
			PDO
			1.09
			★★★★★
			–
			–
			raised medianpedestrian
			rural
			principal arterial
			69 (2004)
			–
			–
			serious/minor
			0.88
			★★★★★
			–
			–
			raised medianpedestrian
			rural
			principal arterial
			69 (2004)
			–
			–
			PDO
			0.82
			★★★★★
			–
			–
			raised medianpedestrian
			urban
			–
			69 (2004)
			–
			–
			fatal/serious/ minor
			0.61
			★★★★
			–
			–
			raised medianpedestrian
			rural
			–
			69 (2004)
			–
			–
			PDO
			2.28
			★★
			–
			–
			raised medianpedestrian
			rural
			–
			69 (2004)
			–
			–
			fatal/serious/ minor
			1.94
			★
			–
			–
			raised medianpedestrian
			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 crosswalkpedestrian
			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 crosswalkpedestrian
			rural
			stop-controlled intersection
			74 (2008)
			–
			–
			all
			0.69
			★★
			–
			PA, KY, MO
			lane narrowing + painted median + rumble stripspedestrian
			rural
			stop-controlled intersection
			74 (2008)
			–
			–
			fatal/serious/ minor
			0.8
			★★
			–
			PA, KY, MO
			lane narrowing + painted median + rumble stripspedestrian
			rural
			stop-controlled intersection
			74 (2008)
			–
			–
			angle
			0.58
			★★
			–
			PA, KY, MO
			lane narrowing + painted median + rumble stripspedestrian
			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-lanepedestrian
			urban
			3-lane
			75 (2003)
			1
			–
			all
			–
			–
			-28%
			MN
			4- to 3-lanepedestrian
			urban
			3-lane
			75 (2003)
			1
			1 yrs./1 yrs.
			all
			–
			–
			-17%
			CA
			4- to 3-lanepedestrian
			urban
			3-lane
			75 (2003)
			1
			1 yrs./1 yrs.
			all
			–
			–
			-17%
			CA
			4- to 3-lanepedestrian
			urban
			3-lane
			75 (2003)
			1
			2 yrs./2 yrs.
			all
			–
			–
			-52%
			CA
			4- to 3-lanepedestrian
			urban
			3-lane
			75 (2003)
			9
			1 yrs./1 yrs.
			all
			–
			–
			-34%
			WA
			4- to 3-lanepedestrian
			urban
			3-lane
			75 (2003)
			9
			1 yrs./1 yrs.
			all
			–
			–
			-57%
			IA
			4- to 3-lanepedestrian
			suburban
			3-lane
			76 (2010)
			30 treatment/  51 control
			17.5 yrs./4.5 yrs.
			all
			0.81
			–
			–
			CA, WA
			4- to 3-lanepedestrian
			small urban
			3-lane
			76 (2010)
			15 treatment/ 296 control
			4.7 yrs./3.5 yrs.
			all
			0.53
			–
			–
			IA
			4- to 3-lanepedestrian
			urban
			3-lane
			77 (2007)
			–
			–
			all
			0.67
			–
			–
			MN
			4- to 3-lanepedestrian
			urban
			3-lane
			77 (2007)
			–
			–
			injury
			1
			–
			–
			MN
			4- to 3-lanepedestrian
			urban
			3-lane
			77 (2007)
			–
			–
			PDO
			0.54
			–
			–
			MN
			4- to 3-lanepedestrian
			urban
			3-lane
			77 (2007)
			–
			–
			angle
			0.76
			–
			–
			MN
			4- to 3-lanepedestrian
			urban
			3-lane
			78 (2012)
			–
			–
			all
			0.95
			★★★
			–
			MI
			4- to 3-lanepedestrian
			urban
			3-lane
			79 (2006)
			15 treatment / 15 control
			11 to 21 yrs./1 to 11 yrs.
			all
			–
			–
			-25%
			IA
			4- to 3-lanepedestrian
			urban
			3-lane minor arterial
			80 (2008)
			–
			–
			all
			0.71
			★★★★
			–
			–
			4- to 3-lanepedestrian
			urban
			3-lane arterial
			78 (2012)
			–
			3 yrs./3 yrs.
			all
			0.91
			–
			–
			MI
			4- to 3-lanepedestrian
			urban
			3-lane arterial
			78 (2012)
			–
			3 yrs./3 yrs.
			not specified
			0.59
			–
			–
			MI
			4- to 3-laneSurface 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, IAroadway departure
			rural
			major collector at stop control
			81 (2010)
			–
			–
			all
			0.67 to 1.4
			★★★
			–
			MN, IAroadway departure
			rural
			major collector at stop control
			81 (2010)
			–
			–
			fatal/serious/ minor
			0.91
			★★★★
			–
			MN, IAroadway departure
			rural
			major collector at stop control
			81 (2010)
			–
			–
			fatal/serious
			0.75
			★★★★
			–
			MN, IAroadway departure
			rural
			major collector at stop control
			81 (2010)
			–
			–
			PDO
			1.2
			★★★★
			–
			MN, IApedestrian
			rural
			low-volume
			82 (2011)
			–
			–
			all
			0.76
			★★★
			–
			China
			at pedestrian crosswalkroadway departure
			rural
			curve
			69 (2004)
			–
			–
			ROR serious/minor
			0.94
			★★
			–
			–
			with RPMsroadway departure
			rural
			–
			83 (1986)
			–
			–
			all
			0.47
			★★
			–
			KY
			with RPMsroadway departure
			rural
			–
			83 (1986)
			–
			–
			wet road
			0.51
			★
			–
			KY
			with RPMsroadway departure
			rural
			–
			83 (1986)
			–
			–
			nighttime
			0.36
			★
			–
			KY
			with RPMsroadway departure
			rural
			–
			83 (1986)
			–
			–
			all
			1.1
			★
			–
			KY
			with RPMs + transverse markingsroadway departure
			rural
			–
			83 (1986)
			–
			–
			wet road
			0.91
			★
			–
			KY
			with RPMs + transverse markingsroadway 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 chevronsroadway departure
			urban
			–
			84 (1996)
			–
			–
			all
			0.68
			★★★
			–
			–
			converging chevronsroadway 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%
			VAVertical 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 delineatorroadway departure
			rural
			–
			69 (2004)
			–
			–
			injury
			1.04
			–
			–
			–
			post mounted delineatorroadway departure
			rural
			curve
			86 (2008); 87 (2005)
			–
			–
			total
			0.70 to 0.80
			–
			–
			–
			post mounted delineatorroadway departure
			rural
			curve (4-lane)
			88 (2009)
			4
			–
			total
			–
			–
			-47%
			Italy
			sequential flashing beacons + chevrons + curve warning signsroadway departure
			rural
			curve (4-lane)
			88 (2009)
			4
			–
			nighttime
			–
			–
			-76%
			Italy
			sequential flashing beacons + chevrons + curve warning signsroadway departure
			rural
			curve (4-lane)
			88 (2009)
			4
			–
			ROR
			–
			–
			-47%
			Italy
			sequential flashing beacons + chevrons + curve warning signsroadway departure
			rural
			curve (4-lane)
			88 (2009)
			4
			–
			rainy
			–
			–
			-42%
			Italy
			sequential flashing beacons + chevrons + curve warning signsroadway departure
			rural
			curve  (4-lane)
			88 (2009)
			4
			–
			injury
			–
			–
			-37%
			Italy
			sequential flashing beacons + chevrons + curve warning signsroadway 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 islandsGateway 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 monumentpedestrian
			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 warningroadway 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 signroadway 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 signroadway 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
			★★
			–
			Netherlandsintersection
			–
			–
			90 (1994)
			181
			–
			PDO
			0.58
			★★
			–
			Netherlandsintersection
			all
			–
			90 (1994)
			181
			–
			vehicle/ped
			0.27
			★
			–
			Netherlandsintersection
			all
			–
			90 (1994)
			181
			–
			vehicle/ped
			0.27
			★
			–
			Netherlandsintersection
			all
			urban/rural
			91 (2013)
			13
			3 yrs./3 yrs.
			fatal/injury
			0.47
			★★★★
			–
			WI
			low speed roundaboutintersection
			all
			urban/rural
			91 (2013)
			11
			3 yrs./3 yrs.
			all
			0.66
			★★★★
			–
			WI
			high speed roundaboutintersection
			all
			urban/rural
			91 (2013)
			11
			3 yrs./3 yrs.
			fatal/injury
			0.51
			★★★
			–
			WI
			high speed roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			all
			0.33
			★★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			injury
			0.13
			★★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			fatal/injury
			0.11
			★★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			angle
			0.17
			★★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			rear-end
			0.85
			★★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			injury angle
			0.09
			★★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			sideswipe
			2.79
			★★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			fixed object
			4.66
			★★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			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 roundaboutintersection
			rural
			rural
			92 (2012)
			19
			98 data yrs./98 data yrs.
			rear-end injury
			0.54
			★★
			–
			MD, WA, KS, WI, MN, OR
			high-speed roundaboutintersection
			all
			urban/rural
			91 (2013)
			13
			3 yrs./ 3 yrs.
			all
			1.1
			★★★★
			–
			WI
			low speed roundaboutintersection
			rural
			one-way stop
			92 (2012)
			2
			98 data yrs./98 data yrs.
			all
			0.74
			★★★
			–
			OR, KS
			3-leg to roundaboutintersection
			rural
			one-way stop
			92 (2012)
			2
			98 data yrs./98 data yrs.
			injury
			0.28
			★★★
			–
			OR, KS
			3-leg to roundaboutintersection
			all
			urban/rural
			91 (2013)
			2
			3 yrs./3 yrs.
			all
			1.24
			★★★
			–
			WI
			no control/yield to roundaboutintersection
			all
			urban/rural
			91 (2013)
			12
			3 yrs./3 yrs.
			all
			1.1
			★★★★
			–
			WI
			multi-lane roundaboutintersection
			all
			urban/rural
			91 (2013)
			12
			3 yrs./3 yrs.
			fatal/injury
			0.37
			★★★★
			–
			WI
			multi-lane roundaboutintersection
			all
			urban/rural
			91 (2013)
			12
			3 yrs./3 yrs.
			all
			0.64
			★★★★
			–
			WI
			single-lane roundaboutintersection
			all
			urban/rural
			91 (2013)
			12
			3 yrs./3 yrs.
			fatal/injury
			0.82
			★★★
			–
			WI
			single-lane roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			all
			urban/rural
			91 (2013)
			5
			3 yrs./3 yrs.
			all
			1.11
			★★★★
			–
			WI
			all-way stop-control to roundaboutintersection
			all
			urban/rural
			91 (2013)
			5
			3 yrs./3 yrs.
			fatal/injury
			0.54
			★★★
			–
			WI
			all-way stop-control to roundaboutintersection
			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 roundaboutintersection
			all
			urban/rural
			91 (2013)
			12
			3 yrs./3 yrs.
			all
			0.75
			★★★★
			–
			WI
			two-way stop-control to roundaboutintersection
			all
			urban/rural
			91 (2013)
			12
			3 yrs./3 yrs.
			fatal/injury
			0.65
			★★★★
			–
			WI
			two-way stop-control to roundaboutIntersection
			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 roundaboutintersection
			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 roundaboutintersection
			rural
			single-lane
			94 (2007)
			9
			3.7 yrs./3.3 yrs.
			all
			0.29
			★★★★
			–
			KS; MD
			minor stop-control to roundaboutintersection
			rural
			single-lane
			94 (2007)
			9
			3.7 yrs./3.3 yrs.
			injury
			0.13
			★★★★
			–
			KS; MD
			minor stop-control to roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			–
			–
			95 (2007)
			62
			3 yrs./1 yrs.
			injury
			0.56
			★★★★
			–
			Belgium
			unsignalized to roundaboutintersection
			–
			–
			95 (2007)
			62
			3 yrs./1 yrs.
			minor injury
			0.54
			★★★★
			–
			Belgium
			unsignalized to roundaboutintersection
			–
			–
			95 (2007)
			62
			3 yrs./1 yrs.
			serious injury
			0.8
			★★★★
			–
			Belgium
			unsignalized to roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			all
			urban/rural
			91 (2013)
			5
			3 yrs./3 yrs.
			all
			0.96
			★★★
			–
			WI
			signalized to single- or multi-lane roundaboutintersection
			urban
			urban/rural
			91 (2013)
			5
			3 yrs./3 yrs.
			all
			0.65
			★★★
			–
			WI
			signalized to single- or multi-lane roundaboutintersection
			urban
			urban/rural
			91 (2013)
			5
			3 yrs./3 yrs.
			injury
			0.26
			★★★
			–
			WI
			signalized to single- or multi-lane roundaboutintersection
			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 roundaboutintersection
			all
			urban/rural
			91 (2013)
			5
			3 yrs./3 yrs.
			fatal/injury
			0.35
			★★★
			–
			WI
			signalized to single- or multi-lane roundaboutintersection
			–
			–
			95 (2007)
			33
			3 yrs./1 yrs.
			injury
			0.68
			★★★★
			–
			Belgium
			signalized to roundaboutintersection
			–
			–
			95 (2007)
			33
			3 yrs./1 yrs.
			major injury
			0.87
			★★★
			–
			Belgium
			signalized to roundaboutintersection
			–
			–
			95 (2007)
			33
			3 yrs./1 yrs.
			minor injury
			0.69
			★★★
			–
			Belgium
			signalized to roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			urban
			multi-lane/single-lane
			94 (2007)
			5
			3.7 yrs./ 3.3 yrs.
			injury
			0.4
			★★★★
			–
			FL, MD, MI, SC
			signalized to roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			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 roundaboutintersection
			rural
			interchange off ramp/on ramp
			98 (2012)
			1
			30 mon/ 6 mon
			all
			0.63
			★★★
			–
			MS
			signalized to roundaboutintersection
			rural
			interchange off ramp/on ramp
			98 (2012)
			1
			30 mon/ 6 mon
			injury
			0.4
			★★★
			–
			MS
			signalized to roundaboutSigning**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 signroadway departure
			rural
			principal arterial/freeways/ expressways
			88 (2009)
			15
			–
			ROR crashes
			0.56
			★★★
			–
			Italy
			with curve warning signroadway departure
			rural
			2-lane
			88 (2009)
			15
			–
			fatal/serious injury/minor injury
			1.46
			★★★
			–
			Italy
			with curve warning signroadway departure
			rural
			2-lane
			88 (2009)
			15
			–
			nighttime
			0.66
			★★★
			–
			Italy
			with curve warning signroadway departure
			rural
			principal arterial/freeways/ expressways
			88 (2009); 99 (2009)
			–
			–
			all crashes on
			0.63 to 1.27
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			principal arterial/freeways/ expressways
			88 (2009); 99 (2009)
			–
			–
			ROR crashes
			0.9
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			on principal arterial/freeways/ expressways
			88 (2009); 99 (2009)
			–
			–
			property damage
			0.83
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			principal arterial/freeways/ expressways
			88 (2009); 99 (2009)
			–
			–
			fatal and injury crashes
			1.46
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			principal arterial/freeways/ expressways
			88 (2009); 99 (2009)
			–
			–
			nighttime
			1.92
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			principal arterial/freeways/ expressways
			88 (2009); 99 (2009)
			–
			–
			wet road crashes on
			0.41
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			2-lane
			88 (2009); 99 (2009)
			–
			–
			all crashes
			0.96
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			2-lane
			88 (2009); 99 (2009)
			–
			–
			head-on/sideswipe
			0.94
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			2-lane
			88 (2009); 99 (2009)
			–
			–
			fatal and injury
			0.84
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			2-lane
			88 (2009); 99 (2009)
			–
			–
			nighttime
			0.75
			★★★
			–
			CA, WA; Italyroadway departure
			rural
			2-lane
			88 (2009); 99 (2009)
			–
			–
			nighttime head-on/sideswipe
			0.78
			★★★
			–
			CA, WA; ItalyAccess 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. https://nacto.org/docs/usdg/chicanes_and_speed_humps_marek.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.  https://dr.lib.iastate.edu/server/api/core/bitstreams/c7661efd-38c5-46ee-be51-39ec768eddd8/content.

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. https://intrans.iastate.edu/app/uploads/2018/03/HPA.pdf.

14.  Dixon, K., H. Zhu, J. Ogle, J. Brooks, C. Hein, P. Aklluir, and M. Crisler.  *Determining Effective Roadway Design Treatments for Transitioning from Rural Areas on State Highways*.  Oregon State University.  FHWA-OR-RD-09-02.  September 2008.

15.  Hallmark, S., S. Knickerbocker, and N. Hawkins.  *Evaluation of Low Cost Traffic Calming for Rural Communities – Phase II*.  Center for Transportation Research and Education, Iowa State University.  September 2013.  https://intrans.iastate.edu/app/uploads/2018/03/updated_rural_traffic_calming_w_cvr2.pdf.

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20.  Ray, B., W. Kittelson, J. Knudsen, B. Nevers, P. Ryus, K. Sylvester, I. Potts, D. Harwood, D. Gilmore, D. Torbic, F. Hanscom, J. McGill, and D. Stewart.  *NCHRP Report 613:  Guidelines for Selection of Speed Reduction Treatments at High-Speed Intersections*.  Transportation Research Board, Washington, DC.  2008.

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27.  Martindale, A. and C. Urlich. *Effectiveness of Transverse Road Markings on Reducing Vehicle Speeds*. NZ Transport Agency Research Report 423. October 2010.

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32.  Katz, B.J.  *Pavement Markings for Speed Reduction*. Science Applications International Corporation. McLean, Virginia. December 2004.

33.  Latoski, S.P.  "Optical Speed Zone for Rural Two-Lane Highways." ITE Journal. March 2009. pp. 30-35.

34.  Gates, T.J., X. Qin, and D.A. Noyce. "Effectiveness of Experimental Transverse-Bar Pavement Marking as Speed-Related Treatment on Freeway Curves."  Journal of the Transportation Research Board. No. 2056. pp. 95-102.

35. Hunter, M.P., A. Guin, S. Boonsiripant, and M. Rodgers.  *Evaluation of the Effectiveness of Converging Chevron Pavement Markings*.  Georgia Department of Transportation.  FHWA-GA-10-0713.  October 2010.

36. Drakapoulos, A., and G. Vergou. *Evaluation of the Converging Chevron Pavement Marking Pattern in One Wisconsin Location*. AAA Foundation for Traffic Safety, Washington, DC. July 2003.

37.  Voigt, A.P. and S.P. Kuchangi.  *Evaluation of Chevron Markings on Freeway to Freeway Connector Ramps in Texas*.  Texas A&M University System.  2008.

38.  ATSSA. *Low Cost Local Road Safety Solutions*.  American Traffic Safety Services Association. Fredericksburg, Virginia. March 2006.

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47. Hallmark, S.L., N. Hawkins, and O. Smadi.  *Evaluation of Low-Cost Treatments on Rural Two-Lane Curves*.  Center for Transportation Research and Education at Iowa State University.  July 2012.  https://intrans.iastate.edu/app/uploads/2018/03/low-cost_treatments_w_cvr.pdf.

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52.  Cruzado, I. and E.T. Donnell.  "Evaluating Effectiveness of Dynamic Speed Display Signs in Transition Zones of Two-Lane, Rural Highways in Pennsylvania." Journal of the Transportation Research Board.  No. 2122.  2009.  pp. 1-8.

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54.  CBTD.  *Stationary Radar Sign Program: 2009 Report*.  2009. City of Bellevue Transportation Department, Bellevue, Washington.

55.  CEC.  "Recent Accomplishments."  www.ci.englewood.co.us/inside-city-hall/boards-and-commissions/transportation-advisory-committee/recent-accomplishments. City of Englewood, Colorado. Accessed June 2013.

56.  Bertini, R.L., C. Monsere, C. Nolan, P. Bosa, and T. Abou El-Seoud. *Field* *Evaluation of the Myrtle Creek Advance Curve Warning System*. SPR 352. FHWA-OR-RD-05_13. Portland State University. June 2006.

57.  Hallmark, S.L., N. Hawkins, and O. Smadi.   *Evaluation of Dynamic Speed Feedback Signs on Curves: A National Demonstration Project*.  Center for Transportation Research and Education at the Institute for Transportation.  Iowa State University.  January 2015.  https://intrans.iastate.edu/app/uploads/2018/03/14020.pdf.

58. Knapp, K. Knapp and Ferrol Robinson.  *The Vehicle Speed Impacts of a Dynamic Horizontal Curve Warning Sign on Low-Volume Local Roadways*.  Minnesota Department of Transportation. May 2012.

59.  Winnett, M.A. and A.H. Wheeler. *Vehicle Activated Signs—A Large Scale Evaluation*. Road Safety Division, Department for Transport. TRL548. 2002.

60.  Drakopoulos, S.U. and Georgia Vergou.  *I-43 Speed Warning Sign Evaluation*.  Marquette University, Milwaukee, Wisconsin.  November 2003.

61.  Tribbett, L., P. McGowen, and J. Mounce. *An Evaluation of Dynamic Curve Warning Systems in the Sacramento River Canyon*. http://www.coe.montana.edu/ce/patm/pubs/files/2000curve.pdf. Western Transportation Institute. April 2000.

62. Pesti, G. and P.T. McCoy.  "Long-Term Effectiveness of Speed Monitoring Displays in Work Zones on Rural Interstate Highways."  80th Annual Meeting of the Transportation Research Board.  January 2011, Washington, DC.

63.  Brewer, M.A., G. Pesti, and W. Schneider IV.  "Improving Compliance with Work Zone Speed Limits:  Effectiveness of Selected Devices."  Journal of the Transportation Research Record.  No. 1948.  2006.  pp. 67-76.

64.  Mattox, J.H., W.A. Sarasua, J.H. Ogle, R.T. Eckenrode, and A. Dunning. "Development and Evaluation of a Speed Activated Sign to Reduce Speeds in Work Zones." Proceedings of the 2007 Annual Meeting of the Transportation Research Board. January 2007.

65. Ulfarsson, G.F., V.N. Shankar, and P. Vu.  "The Effect of Variable Message and Speed Limit Signs on Mean Speeds and Speed Deviations."  International Journal of Vehicle Information and Communication.  Vol. 1.  Nos. 1/2.  February 2005.  pp. 69-87.

66.  Ritchie, S. and M. Lenters.  "High Speed Approaches at Roundabouts."  Presented at the Transportation Research Board National Roundabout Conference.  Vail, CO.  2005.

67.  Waddell, E. and J. Albertson.   "The Domondale Mini:  America's First Mini-Roundabout. Presented at the Transportation Research Board National Roundabout Conference."  Vail, CO.  2005.

68.  Ariniello, A.  "Are Roundabouts Good for Business?"  Presented at the Transportation Research Board National Roundabout Conference.  Vail, Colorado.  2005.

69.  Elvik, R. and T. Vaa.  *Handbook of Road Safety Measures*.  Elsevier, Oxford, United Kingdom. 2004.

70.  Schultz, G., D. Thurgood, A. Olsen, C.S. Reese. "Analyzing Raised Median Safety Impacts Using Bayesian Methods." Presented at the 90th Meeting of the Transportation Research Board, Washington, D.C. 2011.

71.  Schultz, G.G., K.T. Braley, and T. Boschert.  "Correlating Access Management to Crash Rate, Severity, and Collision Type." TRB 87th Annual Meeting Compendium of Papers CD-ROM. Washington, D.C. 2008.

72.  Yanmaz-Tuzel, O. and K. Ozbay. "A Comparative Full Bayesian Before-after Analysis and Application to Urban Road Safety Countermeasures in New Jersey."  Accident Analysis and Prevention. Vol. 42, No. 6. 2010. pp. 2099-2107.

73.  Zegeer, C. V., R. Stewart, H. Huang, and P. Lagerwey.  *Safety Effects of Marked Versus Unmarked Crosswalks at Uncontrolled Locations: Executive Summary and Recommended Guidelines*.  FHWA-RD-01-075. McLean, Va., Federal Highway Administration. 2002.

74.  Bared, J., W. Hughes, R. Jagannathan and F. Gross. *Two Low Cost Safety Concepts for Two Way Stop Controlled, Rural Intersections on High Speed Two Lane, Two Way Roadways*.  FHWA-HRT-08-063. Federal Highway Administration, Washington, DC. 2008.

75.  Knapp, K.K., K.L. Giese, and W. Lee.  "Urban Minor Arterial Four-Lane Undivided to Three-Lane Conversion Feasibility:  an Update."  Presented at the 2nd Urban Street Symposium, Anaheim, California.  July 2003.

76.  Persaud, B. and C. Lyon.  *Evaluation of Lane Reduction "Road Diet" Measures on Crashes*.  Highway Safety Information System Summary Report.  USDOT, FHWA.  FHWA-HRT-10-053.  2010.

77.  Gates, T. J., D.A. Noyce, V. Talada, and L. Hill, L.  "The Safety and Operational Effects of Road Diet Conversion in Minnesota." 2007 TRB 86th Annual Meeting: Compendium of Papers CD-ROM.  Washington, D.C. 2007.

78.  Lyles, R.W., M.A. Siddiqui, W.C. Taylor, B.Z. Malik, G. Siviy, and T. Haan. *Safety and Operational Analysis of 4-lane to 3-lane Conversions (Road Diets) in Michigan*. Michigan Department of Transportation Report Num RC-1555. 2012.

79.  Pawlovich, M.D., W. Li, A. Carriquiry, and T. Welch.  "Iowa's Experience with Road Diet Measures:  Use of Bayesian Approach to Assess Impacts on Crash Frequencies and Crash Rates."  Journal of the Transportation Research Board.  No. 1953.  2006.  pp. 163-171.

80.  Harkey, D.L., R. Srinivasan, J. Baek, B. Persaud, C. Lyon, F.M. Council, K. Eccles, N. Lefler, F. Gross, E. Hauer, and J. Bonneson.  *Crash Reduction Factors for Traffic Engineering and ITS Improvements*.  NCHRP Project 17-25 Final Report.  National Cooperative Highway Research Program, Transportation Research Board, Washington, D.C. 2008.

81.  Srinivasan, R., J. Baek, and F. Council.  "Safety Evaluation of Transverse Rumble Strips on Approaches to Stop-Controlled Intersections in Rural Areas."  Presented at the 89th Annual Meeting of the Transportation Research Board, Washington, D.C. 2010.

82.  Liu, P., J. Huang, W. Wang, and C. Xu.  "Effects of Transverse Rumble Strips on Safety of Pedestrian Crosswalks on Rural Low-Volume Roads in China." Presented at the 90th Meeting of the Transportation Research Board.  Washington, D.C.  2011.

83.  Agent, K. R. and F.T. Creasey.  *Delineation of Horizontal Curves*. UKTRP-86-4.  Frankfort, Ky., Kentucky Transportation Cabinet.  1986.

84.  Griffin, L. I. and R.N. Reinhardt.  *A Review of Two Innovative Pavement Patterns that Have Been Developed to Reduce Traffic Speeds and Crashes*.  AAA Foundation for Traffic Safety, Washington, D.C. 1996.

85. McGee, H.W. and F.R. Hanscom. *Low-Cost Treatments for Horizontal Curve Safety*. U.S. Department of Transportation. Federal Highway Administration. FHWA-SA-07-002. December 2006. http://safety.fhwa.dot.gov/roadway_dept/horicurves/fhwasa07002/index.cfm#toc

86. US DOT. *Toolbox of Countermeasures and Their Potential Effectiveness for Roadway Departure Crashes*. U.S. Department of Transportation, Federal Highway Administration. FHWA-SA-07-013. August 2008.

87. Gan, A., J. Shen, and A. Rodriguez. *Update of Florida Crash Reduction Factors and Countermeasures to Improve the Development of District Safety Improvement Projects*. Florida Department of Transportation. 2005.

88. Montella, Alfonso. "Safety Evaluation of Curve Delineation Improvements Empirical Bayes Observational Before-and-After Study." Transportation Research Record: Journal of the Transportation Research Board. No. 2103. Transportation Research Board of the National Academies, Washington, DC. 2009. pp. 69-79.

89. Veneziano, David, Zhirui Ye, Jim Fletcher, Jon Ebeling, and Frederica Shockley.  *Evaluation of the Gateway Monuments Demonstration:  Safety, Economic and Social Impact Analysis*.  State of California, Department of Transportation, Landscape Architecture Program, and Division of Research and Innovation.  September 2009.  www.dot.ca.gov/hq/LandArch/research/docs/final_gateway_monument_eval.pdf.  Accessed July 2013.

90.  Schoon, C. and J. van Minnen. "The Safety of Roundabouts in the Netherlands." *Traffic Engineering & Control*.  Vol. 35, No. 3.  1994.  pp. 142-148.

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92. Isebrands, H. "A Statistical Analysis and Development of a Crash Prediction Model for Roundabouts on High-Speed Rural Roadways." Presented at the 91st Annual Meeting of the Transportation Research Board Paper No. 12-4191, Washington, D.C.  2012.

93. Persaud, B. N., R.A. Retting, P.E. Garder, and D. Lord. "Observational Before-After Study of the Safety Effect of U.S. Roundabout Conversions Using the Empirical Bayes Method." Journal of the Transportation Research Record.  No. 1751.  Washington, D.C., Transportation Research Board, National Research Council.  2001.

94. Rodegerdts, L. A., M. Blogg, E. Wemple, E. Myers, M. Kyte, K. Dixon, G. List, A. Flannery, A., R. Troutbeck, W. Brilon, N. Wu, B. Persaud, C. Lyon, D. Harkey, and D. Carter.  *NCHRP Report 572: Applying Roundabouts in the United States*.  Washington, D.C. Transportation Research Board, National Research Council.  2007.

95. De Brabander, B. and L. Vereeck. "Safety Effects of Roundabouts in Flanders: Signal Type, Speed Limits, and Vulnerable Road Users."  Accident Analysis and Prevention.  Vol. 39. 2007.

96. Gross, F., C. Lyon, B. Persaud, and R. Srinivasan. "Safety Effectiveness of Converting Signalized Intersections to Roundabouts." Accident Analysis and Prevention.  Vol. 50.  pp. 234-41.  July 2013.

97. Srinivasan, R., J. Baek, S. Smith, C. Sundstrom, D. Carter, C. Lyon, B. Persaud, F. Gross, K. Eccles, A. Hamidi, and N. Lefler.  *NCHRP Report 705: Evaluation of Safety Strategies at Signalized Intersections*. Washington, D.C., Transportation Research Board, National Research Council.  2011.

98. Uddin, W., J. Headrick, and J.S. Sullivan. "Performance Evaluation of Roundabouts for Traffic Flow Improvements and Crash Reductions at a Highway Interchange in Oxford, MS."  Presented at the Transportation Research Board 91st Annual Meeting Compendium of Papers, Washington, D.C., 2012.

99.  Srinivasan, R., J. Baek, D. Carter, B. Persaud, C. Lyon, K. Eccles, F. Gross, and N. Lefler. *Safety Evaluation of Improved Curve Delineation*.  FHWA-HRT-09-045. Federal Highway Administration, Washington, D.C. 2009.

100.  ITE.  *Traffic Calming State of the Practice*.  Institute of Transportation Engineers.  August 1999.
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