1

This chart summarizes studies about engineering countermeasures used to manage speeds. Studies where an increase in speed were reported are also shown since this information 

is also relevant in selection of countermeasures. 

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Vertical Deflections Within the Roadway

Speed Hump—rounded, 

raised area placed across 

the roadway, typically 12 to 

14 feet long  

pedestrian urban local 1 (1999) 178 — 48 to 

11544

46 to 

110443 — — — 35 27 -8 — various

pedestrian urban local 2 (2005) 7 — 400 to 

4362

401 to 

3384 — — — 32 26 -6 — VA 

pedestrian urban local 3 (2000) 4 — 475 to 

1506

433 to 

1343 — — — 36 31 -5 — WA

pedestrian urban local 4 (2005) 1 25 1300 — 22 23 1 37 29 -8 1-mon FL

pedestrian rural/urban local 5 (2002) 3 25 218 to 

746 — 24 18 -6 28 22 -6 1-mon IA

pedestrian urban — 1 (1999) 4 — — — — — — 36 29 -7 — — with speed table

pedestrian urban — 1 (1999) 2 — 2456 to 

3685

2593 to 

2931 — — — 38 25 -13 — — with choker

Engineering Speed Management Countermeasures: A Desktop Reference of 

Potential Effectiveness in Reducing Speed

July 2014

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

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Speed Cushion—raised 

area typically 6 to 7 feet 

wide that allows most 

emergency vehicles to 

straddle the hump

pedestrian urban — 1 (1999) 1 — 3323 2321 — — — 35 28 -7 — various

pedestrian — — 2 (2005) 2 — 1042 to 

1556

693 to 

1563 — — — 31 to 37 26 to 30 -5 to -7 — VA

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 — 1 (1999) 72 — 198 to 

14500

242 to 

14400 — — — 37 31 -6 — various

pedestrian urban residential 6 (2003) 19 — 198 to 

2102

364 to 

2061 — — — 38 29 -9 — GA

pedestrian rural 

community 2-lane 7 (2007) 1 — 1200 — 27 24 -3 33 29 -4 1-mon IA

pedestrian rural 

community local 5 (2002) 3 25 218 to 746 — 24 18 -6 28 22 -6 1-mon IA removable speed table

pedestrian urban — 1 (1999) 2 — 6500 to 

8440

6400 to 

6780 — — — 37 29 -8 — — with center island 

pedestrian urban residential 8 (2001) 1 30 1600 — 34 23 -11 38 27 -11 within 12-

mon

MN raised crosswalk

Raised Intersection—a 

raised plateau, with ramps 

on all approaches, where 

roads intersect  

pedestrian urban — 1 (1999) 2 — — — — — — 37 38 1 — various

pedestrian urban local 9 (2004) 1 — — — — — — 30 30 0 12-mon NY

Horizontal Deflections/Roadway Narrowing

Choker/Bulb-out—midblock curb extensions that 

narrow road by extending 

the sidewalk or widening 

the planting strip 

pedestrian urban — 1 (1999) 4 — 750 to 

6150

331 to 

5040 — — — 34 30 -4 — various

pedestrian urban residential 10 (1997) 6 — — — — — — 30 29 -1 — —

pedestrian urban residential 8 (2001) 1 — 950 to 

1050 — 34 31 -4 38 34 -4 within 12-mon

MN choker with 

crosswalk

pedestrian urban residential 8 (2001) 1 — 950 to 

1050 — 33 31 -2 37 34 -3 within 12-mon

MN choker + “SLOW” 

+ landscaping

pedestrian rural 

community 2-lane 11 (2010) — — — — 39 39 0 — — — — simulator curb + gutter bulb-outs

Neck Down—intersection 

curb extensions that 

narrow a road by 

extending the width of a 

sidewalk  

pedestrian urban — 1 (1999) 3 — 2800 to 

8110

4660 to 

5660 — — — 29 30 1 — various

pedestrian urban local street 9 (2004) 2 — — — 23 25 2 27 31 4 12-mon NY
3

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Chicanes—curb 

extensions that alternate 

from one side of the street 

to the other forming 

s-shaped curves, also 

includes lateral shifts which 

shift traffic to one side of 

the road for an extended 

distance and then back 

pedestrian urban — 10 (1997) 2 — 1380 to 

3200

790 to 

2400 — — — 33 27 -6 — various

pedestrian urban residential 3 (2000) 4 —

1380 to 

1965 

790 to 

1993 — — — 31 22 -9 at least 4 years

WA

pedestrian urban arterial (school 

zone) 12 (1998) 1 — 8000 — — — — 31 28 -3 — Canada

pedestrian rural 

community 2-lane 11 (2010) — — — — 39 30 -9 — — — — simulator

pedestrian rural 

community 2-lane 11 (2010) — — — — 39 33 -6 — — — — simulator painted chicane

Center Island—raised or 

painted island along the 

centerline that narrows 

travel lanes 

pedestrian urban — 1 (1999) — — — — — — — — — — — various

pedestrian urban — 1 (1999) 2 — 6500 to 

8440

6400 to 

6780 — — — 37 29 -8 — —

pedestrian urban local street 9 (2004) 1 — — — 30 28 -2 36 33 -3 12-mon NY

pedestrian rural — 13 (2002) 2 — — — — — — 44 38 -6 1-mon MN

pedestrian rural

within 

community 

(2-lane)

13 (2002) 1 30 900 — 34 29 -5 44 38 -6 2-wks MN

pedestrian rural

within 

community 

(2-lane)

13 (2002) 1 30 900 — 35 31 -4 44 38 -6 6-wks MN

pedestrian rural

community 

entrance

(2-lane)

7 (2007) 2 25 2669 — 31 29 -1 36 35 -1 1-mon IA

combined 

+ tubular 

channelizers

pedestrian rural

community 

entrance 

(2-lane)

14 (2008) — 35 — — 41 43 2 51 50 -1 — simulator median

pedestrian rural

community 

entrance 

(2-lane)

14 (2008) — 35 — — 41 40 -1 52 46 -6 — simulator median + 

gateway

pedestrian rural

community 

entrance 

(2-lane)

14 (2008) — 35 — — 41 41 0 52 50 -2 — simulator median in series

pedestrian rural

community 

entrance 

(2-lane)

14 (2008) — 35 — — 41 40 -1 51 46 -5 — simulator median in series 

with crosswalk

pedestrian rural

community 

entrance 

(2-lane)

15 (2013) 3 25 593 to 

1448 — 28 27 1 35 34 -1 1-mon IA temporary curbing
4

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

(cont’d) Center Island—

raised or painted island 

along the centerline that 

narrows travel lanes

pedestrian rural

community 

entrance 

(2-lane)

15 (2013) 3 25 593 to 

1448 — 29 27 -2 35 33 -2 12-mon IA temporary curbing

pedestrian rural

community 

entrance 

(2-lane)

16 (1999) 5 — — — 38 29 -9 44 33 -11 — Austria braking islands

roadway 

departure rural 2-lane 17 (2008) 8 50 to 55 — — — — -4 — — -5 — Austria painted island + edge line 

Reduce Lane Width with 

Markings—narrowing of 

the lanes using pavement 

markings, median, etc.  

pedestrian rural 

community 2-lane 7 (2007) 2 30 1680 — 28 29 1 34 35 1 1-mon IA

narrowing 

with pavement 

marking 

pedestrian rural 

community 2-lane 7 (2007) 2 30 1680 — 28 29 1 34 35 1 12-mon IA

narrowing 

with pavement 

marking 

pedestrian urban residential 18 (1984) 2 — — — 34 34 0 — — — 1-wk FL

narrowing using 

edgeline + 

centerline

intersection rural intersection 

(2-lane) 19 (2008) 9 50 to 55 — — — — -4 — — -5 3-mon PA, KY, MO, FL edgeline + centerline

roadway 

departure urban

high speed 

intersection 

4-lane

20 (2008) — — — — — — -4 — — — — — 2.7 ft. lane width 

reduction

roadway 

departure urban freeway exit 21 (2000) — — — — 31 30 -1 — — — 1-mon VA

narrowing using 

herringbone 

markings

roadway 

departure rural day 2-lane 22 (2005) 3 — — — 57 58 1 — — — 1-mon TX edgeline + centerline

roadway 

departure rural night 2-lane 22 (2005) 3 — — — 60 59 1 — — — 1-mon TX edgeline (existing centerline 

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 4-lane undivided 23 (2001) 1 — — — — — -4 — — — — CA 4- to 3-lane

pedestrian urban 4-lane undivided 23 (2001) 1 — — — 35 32 -3 — — — — IA 4- to 3-lane

pedestrian urban 4-lane undivided 23 (2001) 1 — — — — — — — — -1 — IA 4- to 3-lane

pedestrian urban minor arterial 8 (2001) 1 35 5400 to 

9100 — 45 43 -2 51 49 -2 — MN 4- to 3-lane
5

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

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  

pedestrian rural high-speed 

intersection 20 (2008) 3 70 — — — — — — — -1 5-mon —

pedestrian rural intersection 24 (2003) 11 — — — — — — 55 54 -1 1-mon TX

roadway 

departure rural 2-lane 25 (2005) 3 — — — 46 46 -0 49 52 3 1-wk KY cars

work zone rural work zone (2-

lane) 26 (2000) 2 — 1250 to 1850 — — — -2 — — — 1-day TX cars

work zone rural work zone (2-

lane) 26 (2000) 2 — 1250 to 1850 — — — -2 — — — 1-day TX trucks

Transverse Bars—lines 

placed across the lane 

perpendicular to direction 

of travel

pedestrian rural community 

entrance (2-lane) 15 (2013) 3 — 843 to 1947 — 38 37 -1 44 44 0 1-mon IA

pedestrian rural community 

entrance (2-lane) 15 (2013) 3 — 843 to 1947 — 37 38 1 44 43 -1 12-mon IA

work zone rural work zone (4-

lane divided) 39 (2003) 1 — — — — — -2 — — -2 — Canada

work zone rural work zone 40 (2001) 1 70 18000 — 64 63 -1 68 67 -1 — KS

Converging Chevrons—

on-pavement chevrons 

roadway 

departure rural freeway to freeway ramp 36 (2003) — — 39010 — 64 49 -15 70 53 -17 20-mon WI

roadway 

departure rural freeway to freeway ramp 37 (2008) — 30 adv. 18000 — 47 47 0 53 52 -1 1-mon TX

roadway 

departure rural freeway to freeway ramp 37 (2008) — 30 adv. 18000 — 48 48 0 53 53 0 6-mon TX

roadway 

departure rural S-curve (2-lane) 38 (2006) 1 35/15 adv. — — — — — 37 33 -4 15-mon OH

pedestrian rural intersection 8 (2001) 1 30 4000 — 36 32 -4 41 35 -6 1-wk MN

pedestrian rural intersection 8 (2001) 1 30 4000 — 36 34 -2 41 39 -2 2-yr MN

pedestrian rural intersection 8 (2001) 1 30 4000 — 36 31 -5 41 35 -5 4-yr MN

pedestrian rural community 

entrance 7 (2007) 2 25 2200 to 2420 — 30 29 -1 36 35 -1 1-mon IA

pedestrian rural community 

entrance 7 (2007) 2 25 2200 to 2420 — 30 29 -1 36 33 -3 12-mon IA

roadway 

departure rural freeway to freeway ramp 35 (2010) — — 18000 to 18600 — 31 29 -2 35 33 -2 1-mon GA

roadway 

departure rural freeway to freeway ramp 35 (2010) — — 18000 to 18600 — 31 30 -1 35 34 -1 9-mon GA converging chevrons
6

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Optical Speed Bars— 

transverse stripes on travel 

lane (sometimes spaced 

progressively closer to 

create the illusion of 

traveling faster)

pedestrian rural intersection 20 (2008) 4 — — — — — -1 — — -1 — —

pedestrian rural community 

entrance 7 (2007) 3 25 to 30 886 to 1870 — 39 38 -1 47 46 -1 1-mon IA

pedestrian rural community 

entrance 7 (2007) 2 25 to 30 234 to 662

263 to 

646 39 34 -5 47 42 -5 1-mon IA

with DSFS 

—”YOUR SPEED 

XX” 

pedestrian rural intersection 27 (2010) 1 — 4,450 — 53 51 -2 62 60 -2 6-mon New Zealand herringbone 

pattern

pedestrian rural community 

entrance 28 (2011) 1 — 2800 — 37 29 -8 — — — — Italy with dragon’s teeth 

intersection rural intersection (2-

lane) 29 (2013) 1 37 — — 42 31 -11 48 3 -13 12-mon Spain

with RPM + 

reflectors to 

guardrail

intersection rural intersection 30 (2000) — 62 — — — — -6 — — — simulator Australia full lane width 

intersection rural intersection 30 (2000) — 62 — — — — -4 — — — simulator Australia optical speed bar

roadway 

departure rural horizontal curves 25 (2005) 3 — — — 46 46 0 49 49 0 1-wk KY transverse bars

roadway 

departure rural horizontal curves 25 (2005) 3 — — — 46 45 -1 49 51 2 1-yr KY transverse bars

roadway 

departure rural 4- lane undivided 31 (2007) 2 45 12000 — 55 52 -3 — — — 1-wk VA transverse bars

roadway 

departure rural 4- lane undivided 31 (2007) 2 45 12000 — 56 49 -7 — — — 3-mon VA transverse bars

roadway 

departure rural curve (2-lane) 32 (2007) 2 45 -65/40 adv. — — 48 49 1 52 56 4 4-mon NY, MI, TX optical speed bar

roadway 

departure rural curve (2-lane) 31 (2007) — — 5215 — 46 44 -2 — — — 1-wk VA optical speed bar

roadway 

departure rural curve (2-lane) 31 (2007) — — 5215 — 46 45 -1 — — — 3-mon VA optical speed bar

roadway 

departure rural 2-lane 33 (2009) — 55 day 45 night — — 64 62 -2 71 69 -2 1-wk AZ optical speed bar

roadway 

departure rural 2-lane 33 (2009) — 55 day/ 45 night — — 64 59 -4 71 68 -3 3-mon AZ optical speed bar

roadway 

departure rural curve (freeway) 34 (2008) — 50 — — 57 54 -3 60 59 -1 1-wk WI optical speed bar

roadway 

departure rural freeway exit ramp 32 (2007) 1 65/30 adv. — — 38 34 -4 44 39 -5 4-mon NY, MI, TX optical speed bar

roadway 

departure rural 2-lane 27 (2010) 1 — 2500 — 51 50 -1 60 59 -1 2-wk New Zealand herringbone
7

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

(cont’d) Optical Speed 

Bars—transverse stripes 

on travel lane (sometimes 

spaced progressively closer 

to create the illusion of 

traveling faster)

roadway 

departure rural 2-lane 27 (2010) 1 — 2500 — 51 48 -3 60 60 0 6-mon New Zealand herringbone

roadway 

departure rural freeway ramp 21 (2000) 4 — — — 33 30 -3 — — — 2-wk NY, VA herringbone markings

pedestrian rural intersection 27 (2010) 1 — 4,450 — 53 52 -1 61 61 0 2-wks — Herringbone

“SLOW” Legend on 

Pavement

pedestrian urban residential 8 (2001) 1 30 950 — 28 29 0 32 33 1 — MN

roadway 

departure urban curve (2-lane) day 41 (1998) 1 35/15 adv 5000 — 34 33 -1 — — — 2-wk VA with curve symbol

roadway 

departure urban curve (2-lane) night 41 (1998) 1 35/15 adv 5000 — 35 32 -3 — — — 2-wk VA with curve symbol

roadway 

departure rural curve 15 (2012) 2

55/none 

to 35 

mph

780 to 

1880 — 49 48 -1 54 53 -1 1-mon IA with curve symbol+ bars

roadway 

departure rural curve 15 (2012) 2

55/none 

to 35 

mph

780 to 

1880 — 49 48 -1 54 53 -1 12-mon IA with curve symbol + bars

Speed Limit XX Pavement 

Legend 

pedestrian rural within 

community 7 (2007) 1 25 2200 — 30 30 0 35 34 -1 1-mon IA

pedestrian rural within 

community 7 (2007) 1 25 2200 — 30 29 -1 35 33 -2 12-mon IA

pedestrian rural within 

community 7 (2007) 1 25 2420 — 28 28 0 32 3 -1 1-mon IA with lane narrowing

pedestrian rural within 

community 7 (2007) 1 25 2420 — 28 29 1 32 33 1 12-mon IA with lane narrowing

pedestrian rural community 

entrance

7 (2007);15 

(2013) 5 25 to 35 1009 to 2850 — 37 35 -2 42 40 -3 1-mon IA with red colored pavement 

pedestrian rural community 

entrance

7 (2007);15 

(2013) 2 25 to 35 1009 to 2850 — 40 39 -1 46 45 -1 12-mon IA with red colored pavement 

pedestrian rural community 

entrance 15 (2013) 3 25 to 35 1009 to 3070 — 35 34 -1 40 39 -1 1-mon IA colored pavement + dragon’s teeth

“50 MPH” + Curve Symbol

roadway 

departure urban

curve 

(divided 4-lane 

highway)

42 (2005) 1 — — — 67 60 -7 — — — 1-mon TX

“CURVE AHEAD” 

Pavement Legend

roadway 

departure rural curve 42 (2005) 1 — 990 — 56 61 5 — — — 3-mon TX

roadway 

departure rural curve 42 (2005) 1 — 1160 — 60 59 -1 — — — 3-mon TX

Vertical Delineation

Center Island Using 

Tubular Channelizers pedestrian rural community

community 

entrance (2-lane) 7 (2007) 2 25 2669 — 30 29 -1 36 35 -1 1-mon IA
8

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Post Mounted 

Delineators—reflective 

buttons place on post at 

edge of road

roadway 

departure rural curve (2-lane) 25 (2005) 3 — — — 46 46 0 49 50 1 1-wk KY

roadway 

departure rural curve (2-lane) 11 (2010) — — — — 43 35 -8 — — — — simulator one side of curve

roadway 

departure rural curve (2-lane) 11 (2010) — — — — 43 34 -9 — — — — simulator both sides of curve

Streaming PMD roadway 

departure rural curve (2-lane) 11 (2010) — — — — 43 24 -19 — — — — simulator

Chevrons with Reflective 

Post

roadway 

departure rural curve (2-lane) 46 (2010) 2 — — — 56 54 -2 65 63 -2 1-mon TX

Reflective Post Added to 

Existing Chevrons

roadway 

departure rural curve (2-lane) 47 (2012) 4 — 830 to 2280 — 50 50 0 56 55 -1 1-mon IA

roadway 

departure rural curve (2-lane) 47 (2012) 1 — 1710 — 54 53 -1 59 57 -2 12-mon IA

Layered Landscaping— 

roadside plantings used to 

create vertical friction

pedestrian rural community 

entrance (2-lane) 14 (2008) — 35 — — 43 44 1 54 53 -1 — simulator at treatment

pedestrian rural community 

entrance (2-lane) 14 (2008) — 35 — — 42 40 -2 51 45 -6 — simulator

300 ft. 

downstream of 

treatment

Landscaped Median roadway 

departure urban collector 48 (2000) 1 — 11400 10900 37 33 -4 43 37 -6 — CO with curbside islands

Dynamic Signing

Speed Activated Speed 

Limit Sign—a blank out 

sign that displays “SPEED 

LIMIT XX” for vehicles 

exceeding threshold speed

roadway 

departure urban collector 55 (2013) 1 30 — — 33 27 -6 36 30 -6 2-mon CO

with striping 

between travel/

parking lanes + 

signing

roadway 

departure urban collector 55 (2013) 2 30 — — — — — 39 34 -5 1-yr CO

with physical 

narrowing + 

pedestrian refuge

roadway 

departure urban collector 55 (2013) 3 30 — — — — — 37 33 -4 1-yr CO

roadway 

departure urban collector 55 (2013) 1 30 — — — — — 37 32 -5 3-yr CO

Speed Limit Sign with LED

pedestrian rural community 

entrance 15 (2013) 2 25 980 to 2240 — 33 30 -3 42 28 -4 1-mon IA

pedestrian rural community 

entrance 15 (2013) 2 25 980 to 2240 — 33 30 -3 42 38 -4 12-mon IA
9

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Speed Feedback Sign—

displays the speed of drivers 

traveling over the threshold 

speed with the message 

“YOUR SPEED XX

pedestrian urban school zone 50 (2005) 3 35 to 45 — — 49 44 -5 55 49 -6 1-wk TX

pedestrian urban school zone 50 (2005) 3 35 to 45 — — 49 42 -7 54 51 -3 4-mon TX

pedestrian rural community 

entrance

7 (2007); 15 

(2013) 1 25 295 367 38 37 -1 46 45 -1 1-mon IA

pedestrian rural community 

entrance

7 (2007); 15 

(2013) 1 25 295 318 38 37 0 46 45 -1 12-mon IA

pedestrian rural community 

entrance 51 (2006) 4 30 to 45 — — 46 41 -5 51 46 -5 1-mon MN

pedestrian rural community 

entrance 51 (2006) 4 30 to 45 — — 47 40 -7 51 46 -5 12-mon MN

pedestrian rural community 

entrance 52 (2009) 12 25 to 40 — — 42 36 -6 — — — 1-wk PA

intersection urban signalized 

intersection 50 (2005) 2 45 to 55 — — 51 47 -4 57 54 -4 1-wk TX

intersection urban signalized 

intersection 50 (2005) 2 45 to 55 — — 51 49 -2 57 55 -2 4-mon TX

roadway 

departure urban collector (2-lane) 53 (2004) 4 25 2700 to 4900 — 29 28 -1 34 32 -5 1-mon WA

roadway 

departure urban collector (2-lane) 53 (2004) 4 25 2700 to 4900 — 28 27 -1 33 28 -5 2-yr WA

roadway 

departure urban collector/ minor arterial 54 (2009) 16 25 — — — — — — — -2 1-yr WA

roadway 

departure urban collector/ minor arterial 54 (2009) 16 25 — — — — — — — -3 5 to 8-yr WA

roadway 

departure urban collector/ minor arterial 54 (2009) 16 30 to 35 — — — — — — — -4 1-yr WA

roadway 

departure urban collector/ minor arterial 54 (2009) 16 30 to 35 — — — — — — — -6 5 to 8-yr WA

roadway 

departure urban 2-lane 54 (2009) 9 25 to 35 — — — — — 40 36 -4 1-mon WA

roadway 

departure urban 2-lane 54 (2009) 4 25 to 35 — — — — — 37 33 -4 12-mon WA

roadway 

departure urban 2-lane 54 (2009) 9 25 to 35 — — — — — 39 35 -4 2 to 3-yr WA

roadway 

departure urban 2-lane 54 (2009) 11 25 to 35 — — — — — 38 33 -5 4+ yr. WA

roadway 

departure urban curve  (2-lane) 54 (2009) 1 30 — — — — — 41 38 -3 1-mon WA

roadway 

departure urban curve (2-lane) 54 (2009) 2 30 to 35 — — — — — 42 38 -4 2 to 3-yr WA
10

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

(cont’d) Speed Feedback 

Sign—displays the speed 

of drivers traveling over the 

threshold speed with the 

message “YOUR SPEED XX”

roadway 

departure urban curve (2-lane) 54 (2009) 1 30 — — — — — 41 35 -6 4+ yr. WA

roadway 

departure rural interstate (curve) 56 (2006) 2 45 adv. 16750 — 56 53 -3 — — — 2 to 4-mon OR passenger cars

roadway 

departure rural interstate (curve) 56 (2006) 2 45 adv. 16750 — 51 49 -2 — — — 2 to 4-mon OR trucks

roadway 

departure rural curve (2-lane) 57 (2013) 11

50 to 

65/30 to 

50 adv.

— — — — -2 — — -3 1-mon AZ, FL, IA, OH, 

OR, TX, WA

roadway 

departure rural curve (2-lane) 57 (2013) 11

50 to 

65/30 to 

50 adv.

— — — — -3 — — -3 12-mon AZ, FL, IA, OH, 

OR, TX, WA

roadway 

departure rural curve (2-lane) 57 (2013) 11

50 to 

65/30 to 

50 adv.

— — — — -2 — — -2 2-yr AZ, FL, IA, OH, 

OR, TX, WA

roadway 

departure rural curve (2-lane) 50 (2005) 2 55/20 adv. — — 36 33 -3 42 39 -3 1-wk TX

roadway 

departure rural curve (2-lane) 50 (2005) 2 55/20 adv. — — 36 35 -1 42 40 -2 4-mon TX

roadway 

departure rural curve (2-lane) 58 (2012) 3 — 455 to 710 — 54 51 -3 61 57 -4 1-mon MN passenger cars

work zone rural interstate 62 (2011) 3 55 28000 — 61 57 -4 66 61 -5 1-wk NE passenger cars

work zone rural interstate 62 (2011) 3 55 28000 — 58 55 -3 62 59 -3 1-wk NE trucks

work zone rural interstate 62 (2011) 3 55 28000 — 61 56 -5 66 60 -6 5-wk NE passenger cars

work zone rural interstate 62 (2011) 3 55 28000 — 58 56 -3 62 59 -3 5-wk NE trucks

work zone rural arterial 63 (2006) 1 — — — — — — 66 63 -3 — TX

Speed Feedback Sign with 

Action Message—“YOUR 

SPEED XX” + “SLOW DOWN”

roadway 

departure urban 2-lane 54 (2009) 9 25 — — — — — 34 32 -2 1 to 6-mon WA

roadway 

departure urban 2-lane 54 (2009) 3 25 — — — — — 33 -31 -2 12-mon WA

roadway 

departure urban 2-lane 54 (2009) 5 25 — — — — — 33 31 -2 2 to 3-yr WA

roadway 

departure urban curve (2-lane) 54 (2009) 1 25 — — — — — 36 31 -5 1 to 6-mon WA

roadway 

departure urban curve (2-lane) 54 (2009) 1 25 — — — — — 36 31 -5 4+ yr. WA

intersection rural signalized 

intersection 20 (2008) 3 50 to 55 — — — — -2 — — -1 — WA, TX at sign

work zone rural interstate 63 (2006) 1 — — — — — — 65 63 -2 — TX

pedestrian rural community 

entrance 7 (2007) 1 25 2870 — 31 26 -5 59 52 -7 3-mon IA SLOW DOWN 25
11

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Speed Feedback Sign 

plus New Curve Advisory 

Speed Sign

roadway 

departure rural curve (2-lane) 58 (2012) 3 — 455 to 710 — 54 50 -4 61 57 -4 12-mon MN PC

roadway 

departure rural curve  (2-lane) 58 (2012) 3 — 455 to 710 — 53 50 -3 53 50 -3 1-mon MN center of curve, 

roadway 

departure rural curve (2-lane) 58 (2012) 3 — 455 to 710 — 53 50 -3 53 49 -4 12-mon MN center of curve

“YOUR SPEED XX” pedestrian rural community 

entrance

7 (2007); 15 

(2013) 2 25 to 30 234 to 662

263 to 

646 39 34 -5 47 42 -5 1-mon IA with optical speed bars

“SLOW” pedestrian rural recreational area 13 (2002) 1 35 — — 36 36 0. 43 44 1 1-mon MN

Speed Activated Curve 

Warning Sign and “SLOW 

DOWN” Action Message

roadway 

departure rural curve (2-lane) 59 (2002) 3 30 to 50 — — 39 35 -4 — — — — United Kingdom

roadway 

departure rural curve (2-lane) 57 (2013) 11

50 to 

70/35 to 

50 adv.

— — — — -2 — — -2 1-mon AZ, FL, IA, OH, 

OR, TX, WA

roadway 

departure rural curve (2-lane) 57 (2013) 11

50 to 

70/35 to 

50 adv.

— — — — -3 — — -2 12-mon AZ, FL, IA, OH, 

OR, TX, WA

roadway 

departure rural curve (2-lane) 57 (2013) 11

50 to 

70/35 to 

50 adv.

— — — — -2 — — -2 2-yr AZ, FL, IA, OH, 

OR, TX, WA

“TOO FAST FOR CURVE” roadway 

departure rural curve (interstate) 60 (2003) 1 50 — — — — -3 — — — — WI trucks

“50 MPH CURVES” + 

“YOUR SPEED XX”

roadway 

departure rural interstate 61 (2000) 5

55 to 

65/50 to 

60 adv.

— — 64 63 -1 — — — — CA passenger cars

“50 MPH CURVES” + 

“YOUR SPEED XX”

roadway 

departure rural interstate 61 (2000) 5

55 to 

65/50 to 

60 adv.

— — 58 56 -2 — — — — CA trucks

Flashing Beacon

work zone rural 2-lane 64 (2007) 3 45 — — — — -3 — — -3 — SC

work zone rural multi-lane 64 (2007) 1 45 — — — — -3 — — -3 — SC

work zone rural interstate 64 (2007) 1 45 — — — — -6 — — -5 — SC

Variable Speed Limit roadway 

departure rural freeway 65 (2005) 2 — — — — — — 82 77 -5 — WA

Curve Warning Sign with 

Flashers— flashing lights 

on sign 

roadway 

departure rural 2-lane curve 25 (2005) 2 — — — 47 46 -1 51 50 -1 — —
12

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Static Signing

Chevron Signs—use of 

standard chevron signing

roadway 

departure rural 2-lane 46 (2010) 2 70/45 & 50 adv. — — 57 55 -2 65 64 -1 1-mon TX

roadway 

departure rural 2-lane 25 (2005) 1 — — — 48 48 0 52 52 0 1-wk KY at PC

roadway 

departure rural 2-lane 46 (2010) 2 70/45 & 50 adv. — — 56 54 -2 65 63 -2 1-mon TX with full post delineation

Chevrons with Full Post 

Delineation

roadway 

departure rural 2-lane 47 (2012) 4

50 to 

55/35 to 

50 adv.

— — 50 50 0 56 55 -1 1-mon IA

Curve Sign + Flags roadway 

departure rural 2-lane 25 (2005) 3 — — — 46 45 -1 49 49 0 1-wk KY at PC

Arrow (MUTCD: W1-6) roadway 

departure rural 2-lane 25 (2005) 1 — — — 43 44 1 46 47 1 1-wk KY at PC

Intersection Treatments

Roundabout—large, 

raised, circular islands 

at the middle of major 

intersections, around which 

all oncoming vehicles must 

traverse

pedestrian rural — 66 (2005) 19 — — 20400 — — — 48 28 -20 — MD, CA, WA, 

MI, Canada 

intersection suburban Y intersection 

(2-lane) 67 (2005) 1 — — 5500 — — — 32 24 -8 1 to 3 years

MI

intersection urban — 68 (2005) 1 — 11000 to 

12000 15500 — — — 47 33 -14 — CO

Traffic Circle—circular, 

raised island placed 

within the middle of an 

intersection 

intersection urban — 1 (1999) 45 — 240 to 

10910

269 to 

8280 — — — 34 30 -4 —

TX, WA, CA, 

CO, NC, OH, 

OR, FL, GA, 

MD, NE, MA, 

MN, AZ

Access Control

Half-Closure pedestrian urban — 1 (1999) 11 — 220 to 

9540

151 to 

9180 — — — 30 24 -6 — —

Diagonal Diverter pedestrian urban — 1 (1999) 7 — 474 to 

2057

177 to 

574 — — — 28 27 -1 — —

Full Closure pedestrian urban — 1 (1999) 2 — 1540 to 

1980

850 to 

1080 — — — 18 13 -3 — —

Choker + Speed Hump pedestrian urban — 1 (1999) 2 — 2456 to 

3685

2593 to 

2931 — — — 38 25 -13 — —

Half-Closure + Median 

Barrier pedestrian urban — 1 (1999) 2 — 10160 to 10320

1120 to 

2120 — — — 38 32 -6 — —
13

Countermeasure Safety 

Focus Area Roadway Reference Sites

Speed 

Limit 

(mph)

Volume (vpd) Mean Speed (mph) 85th %tile Speed (mph)

Period Location Notes

Before After Before After Change Before After Change

Gateway Entrance Treatments

Entrance Treatments—

multiple treatments placed 

at community entrance 

to reduce speeds into 

community 

pedestrian rural community 

entrance 49 (2000) 1 40 — — 45 41 -4 50 46 -5 1-mon United Kingdom

red bars + signing 

+ bulb-outs

pedestrian rural community 

entrance 49 (2000) 1 20 — — 35 24 -11 41 30 -11 1-mon United Kingdom

narrowing + 

speed cushions

pedestrian rural community 

entrance 49 (2000) 1 20 — — 35 15 -10 41 30 -11 12-mon United Kingdom

narrowing + 

speed cushions

pedestrian rural community 

entrance 49 (2000) 1 30 — — 40 30 -11 47 35 -13 1-mon United Kingdom

red box + speed 

limit + dragon’s 

teeth + signing

pedestrian rural community 

entrance 49 (2000) 1 30 — — 40 33 -8 47 38 -9 12-mon United Kingdom

red box + speed 

limit + dragon’s 

teeth + signing

pedestrian rural community 

entrance 49 (2000) 1 30 — — 38 33 -5 43 39 -4 1-mon United Kingdom

red box + speed 

limit + dragon’s 

teeth + signing

pedestrian rural community 

entrance 49 (2000) 1 30 — — 38 32 -6 43 36 -7 12-mon United Kingdom

red box + speed 

limit + dragon’s 

teeth + signing

pedestrian rural community 

entrance 49 (2000) 1 30 — — 41 39 -2 47 47 0 1-mon United Kingdom

red patches + 

“SLOW” + dragon’s 

teeth + signing 

pedestrian rural community 

entrance 49 (2000) 1 30 — — 41 37 -4 47 44 -3 12-mon United Kingdom

red patches + 

“SLOW” + dragon’s 

teeth + signing

pedestrian rural community 

entrance 49 (2000) 1 40 — — 51 45 -6 60 51 -9 1-mon United Kingdom

red lines of 

decreasing size 

and width + 

signing

pedestrian rural community 

entrance 49 (2000) 1 40 — — 51 45 -6 60 53 -7 12-mon United Kingdom

red lines of 

decreasing size 

and width + 

signing

pedestrian rural community 

entrance 49 (2000) 1 40 — — 44 39 -6 50 43 -7 1-mon United Kingdom

red box + speed 

limit + signing 

pedestrian rural community 

entrance 49 (2000) 1 40 — — 44 38 -7 50 43 -7 12-mon United Kingdom

red box + speed 

limit + signing 

Notes: Information is presented to one significant digit unless the study only provided integer values. In some cases the study only provided resulting changes in speed rather than providing the actual before and after value.
14

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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