Engineering Countermeasures for Reducing Speeds

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A Desktop Reference of Potential Effectiveness

May 2009

Countermeasure Area Road Environment Reference # (Year) Sample Size (# of Sites) After Measurement Average Daily Volumes 85th Percentile Speeds
Before (veh) After (veh) Before(mph) After (mph) Change (mph) %Change
GEOMETRIC FEATURES
Speed Hump-rounded raised area across the road, typically 12 to 14 feet in length and 3 to 4 inches high Urban Local Street 1 (1999) 178   48 to 11544 46 to 11043 35 (4) 27 (4) -8 (3) -22% (9%)
  Local Street 2 (2005) 7   400 to 4362 401 to 3384 32 (3) 26 (2) -6 (2) -20% (6%)
  Local Street 4 (2000) 4   475 to 1506 433 to 1343 36 (2) 31 (2) -5 (1) -15% (3%)
Speed Cushion-speed hump typically 6 to 7 feet wide that allows most emergency vehicles to straddle the hump. Urban   1 (1999) 1   3323 2321 35 (-) 28 (-) -7 (-) -20% (-)
    2 (2005) 2   1042 to 1556 693 to 1563 31 to 37 26 to 30 -5 to -7 -16% to 19%
Speed Table-a long speed hump typically 22 feet in length with a flat section in the middle and ramps on the ends Urban   1 (1999) 72   198 to 14500 242 to 14400 37 (3) 31 (3) -6 (3) -16% (9%)
Rural Small town 3 (2008) 2 12 month 1480   33 (1) 29 (2) -4 (1) -14% (3%)
  Residential Streets 18 (2003) 19   198 to 2102 364 to 2061 38 (n/a) 29 (n/a) -9 (n/a) -24% (n/a)
Raised Intersection-a raised plateau, with ramps on all approaches, where roads intersect Urban   1 (1999) 2       37 (1) 38 (4) 1 (4) 3% (11%)
Urban Local Street 5 (2004) 1       30 (-) 30 (-) 0 (-) 0% (-)
Choker-mid-block curb extensions that narrow a road by extending the sidewalk or widening the planting strip Urban   1 (1999) 4   770 to 6150 331 to 5040 34 (2) 30 (2) -4 (1) -3% (3%)
Urban Residential Area 51 (1977) 6       30 (4)95%tile 29 (3) 95%tile -1 (2) 95%tile -3% (7%) 95%tile
Neckdown-intersection curb extensions that narrow a road by extending the width of a sidewalk Urban   1 (1999) 3   2800 to 8110 4660 to  5660 29 (9) 30 (3) 1 (7) 3% (30%)
Urban Local Street 5 (2004) 2       28 (3) 31 (4) 3 (7) 12% (27%)
Chicane-curb extensions that alternate from one side of the street to the other, forming S-shaped curves. Urban   1 (1999) 2   1380 to 3200 790 to  2400 33 (4) 27 (4) -6 (1) -16% (4%)
    4 (2000) 4 at least 4 years 1380 to 1965 790 to 1993 31 (6) 22 (4) -9 (4) -29% (8%)
Urban School Zone 42 (1998) 1   8000   31 (-) 28 (-) -3 (-) -10% (-)
Lateral Shift-curb extension that shifts travel lanes to one side of road for extended distance and then back to the other side Urban Local Street 5 (2004) 1       36 (-) 33 (-) -3 (-) -8% (-)
Rural At City Limits 19 (1999) 5       44 (4) 33 (4) -11 (7) -25% (9%)
Center Island-a raised island along the centerline of a street that narrows the travel lanes Urban   1 (1999) 1   3500 2800 33 (-) 29 (-) -4 (-) -12% (-)
Traffic Circle-circular, raised island placed within the middle of an intersection Urban   1 (1999) 45   240 to 10910 269 to 8280 34 (5) 30 (4) -4 (3) -11% (9%)
Roundabout-large, raised, circular islands at the middle of major intersections, around which all oncoming vehicles must travel until reaching their destination street, where they then turn off.   Transition from High to Low Speed 36 (2005) 1       48 (-) 28 (-) -20 (-) -42% (-)
Suburban Y Intersection of  two-lane roads 37 (2005) 1       32 (-) 24 (-) -8 (-) -25% (-)
Urban   38 (2004) 1       47 (-) 33 (-) -14 (-) -30% (-)
Urban & Rural Intersection entry 54 (2007) 55         20 (4)    
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. Rural Posted Speed Limit=70mph 17 (2007) 3 5 months         -0.6 (0.4)  
Rural Intersection 23 (2003) 11 At least 1 month         -1 to -2  
Converging Chevron Marking Pattern-a type of transverse pavement markings forming chevron shape to create the illusion of traveling faster as well as the impression of narrower lanes. Rural Main Roads 3 (2008) 2 12 months 2300   36 (1) 33 (1) -3 (2) -7% (6%)
  Double S-Curve On A Two- Lane Roadway 7 (2006) 1 15 months     37 (-) 33 (-) -4 (-) -11% (-)
Urban Exit Ramps 12 (2003) 1 20 months     70 (-) 53 (-) -17 (-) -24% (-)
  Community Collector Street 13 (2001) 1 2 years     41 (-) 39 (-) -2 (-) -5% (-)
  Freeway-to-Freeway Connector Curve 48 (2008) 1 6 months 18000   53.4 (-) 52.8 (-) -0.6 (-) -1% (-)
Transverse Markings-a series of white lines placed across the center of the lane and spaced progressively closer to create the illusion of traveling faster Rural Horizontal Curves 20 (2005) 3 5 days     49 (3) 50 (3) 0.2 (1.7) 0.3% (3%)
Rural Interstate Work Zone 46 (2001) 1   18000   68 (-) 67 (-) -1 (-) -1% (-)
Optical Speed Bars-a series of white rectangular markings typically 1 foot wide placed just inside both edges of the lane and spaced progressively closer to create the illusion of traveling faster as well as the impression of narrower lane. Rural Main Roads 3 (2008) 1 12 months     46 (-) 45 (-) -1 (-) -2% (-)
Rural Main Roads 3 (2008) 2 3 months 1000   47 (8) 46 (-) -1 (0) -2% (0)
Rural Curve 11 (2004) 3       37 (6) 36 (10) -1 (4) -2% (8%)
Rural Two-Lane Highway;  Tourist Traffic 45 (2009) 1 3 months     71 (-) 66 (-) -5 (-) -7% (-)
Rural Freeway Curves 53 (2008) 1 6 months 63,072 57,948 61 (-) 60 (-) -1 (-) -2% (-)
Speed Limit Pavement Legend Rural Main Roads 3 (2008) 4 12 months     34 (3) 33 (2) -1 (1) -1% (4%)
Enhanced Speed Limit Legend with Colored Surfacing Rural Main Roads 3 (2008) 3 12 months 1000   46 (6) 44 (6) -2 (2) -4% (4%)
In-Roadway Warning Lights Urban Residential Area; Pedestrian Crossing 15 (2000) 2 1 month 30,000   46 (0) 39 (1) -7 (1) -15% (1%)
  School Zone 33   1 year     58 (-) 53 (-) -5 (-) -9% (-)
Urban Central Business District; Pedestrian Crossing 34 (2004) 1 2 weeks 25,000   21 (-) 22 (-) 1 (-) 5% (-)
  Freeway Off-Ramp 39 (2008) 1 14 months     57 (-) 53 (-) -4 (-) -7% (-)
Delineator Post Rural Horizontal Curves 20 (2005) 3 5 days     49 (3) 50 (3) 0.5 (0.4) 1% (1%)
“Slow” Pavement Legend Rural Main Roads 3 (2008) 3 9 months 2940   40 (6) 41 (8) 1 (2) 1% (4%)
Suburban Curve on Two-Lane Road 47 (1998) 1 2 weeks 5000   39 (-) 37 (-) -2 (-) -5% (-)
SIGNS
Speed Feedback Sign-sign that dynamically displays speed of passing vehicles with the message “YOUR SPEED XX” Rural Main Roads 3 (2008) 1 3 months 2870   37 (-) 30 (-) -7 (-) -19% (-)
  15mph School Zone 8 (2002) 1       48 (-) 15 (-) -33 (-) -69% (-)
  School Zone 8 (2002) 1       32 (-) 25 (-) -7 (-) -22% (-)
  School Zone 14 (2005) 1 2 to 4 months     50 (-) 42 (-) -8 (-) -16% (-)
  Advance of School Zone 14 (2005) 2 2 to 4 months     57 (6) 56 (7) -1 (1) -2% (3%)
  Advance of Signalized Intersection 14 (2005) 2 2 to 4 months     57 (10) 56 (12) -1 (2) -3% (4%)
  Non-freeway 9 (2005) 20 6 to 39 months     35 (3) 32 (2) -3 (2) -7% (4%)
  Collector Street/Residential Cross Street 10 (2007) 6 3 years     37 (2) 33 (1) -4 (2) -11% (4%)
  School Zone 26 (2006) 8 6 months     25 (2) 24 (2) -1 (2) -5% (7%)
Rural Work Zone on Interstate Highway 27 (2001) 3 5 weeks 38000   65 (2) 60 (2) -5 (1) -8% (1%)
  School Zone 28 (2003) 2 2 months 8000 to 9200   30 (5) 28 (4) -2 (1) -7% (1%)
  School Zone 28 (2003) 2 2 months 11800 to 29200   43 (1) 34 (0) -9 (1) -22% (1%)
  Two-Lane Collector Arterial, Near to School Zone 29 (2005) 4 7 months 1486 to 2794 1270 to 2533 34 (2) 32 (3) -2 (1) -3% (4%)
Rural Interstate Highway Work Zone 32 (2006) 1 1 week     65 (-) 63 (-) -2 (-) -3% (-)
Speed Activated Warning Sign-sign that displays warning messages to speeding drivers   Posted Speed Limit=50/55mph 17 (2007) 4 at least 3 months         -1.4 (0.1)  
  Work Zone at State Route 25 (2007) 3   122 to 250       -1 to -6.5  
Multilane US Highway 25 (2007) 1           -1.6 to -4.7  
Multilane Interstate 25 (2007) 2           -3.0 to -11.2  
Urban U.S. Highway Work Zone 32 (2006) 1 1 week     67 (-) PC;65 (-) Truck 64 (-) PC;63 (-) Truck -3 (-) PC;-2 (-) Truck -4% (-) PC;-3% (-) Truck
Urban & Rural Work Zone 35 (2007) 2       54 (4) 49 (6) -5 (3) -10% (5%)
Rural Four-Lane Divided Highway 43 (1999) 1   7000   73 (-) 69 (-) -4 (-) -5% (-)
  Curve on Interstate Freeway 44 (2003) 1   65000   63 (-) 62 (-) -1 (-) -2% (-)
Speed Activated Speed Limit Reminder Sign   Major Road 6 (2005) 1       42 (-) 37 (-) -5 (-) -12% (-)
  School Zone 24 (2001) 1 2 months     43 (-) 37 (-) -6 (-) -14% (-)
Variable Speed Limit Sign Rural Finland, weather-controlled 31 (1999) 3           -4.7 to -8  
Rural Freeway 40 (2005) 2       82 (1) 77 (6) -5 (5) -6% (6%)
Lower Speed Limit by 15+ mi/h Urban & Rural 2 lane roads 21 (1997) 9 12-24 months     49 (5) 49 (4) -0.1 (1) -0.1% (3%)
Lower Speed Limit by 10 mi/h Urban & Rural 2 & 4 lane roads 21 (1997) 34 12-24 months     50 (5) 50 (5) -0.1 (1) -0.6% (2%)
Lower Speed Limit by 5 mi/h Urban & Rural 2 lane roads 21 (1997) 14 12-24 months     51 (6) 50 (6) -0.3 (1) -0.1% (2%)
Red Border Speed Limit Sign Rural Two-Lane highway 30 (2007) 3 8 to 14 months         -3 (4)  
One-Direction Large Arrow (W1-6) sign Rural Horizontal Curves 20 (2005) 1 5 days     47 (-) 47 (-) 0 (-) 0% (-)
Add Flashers to Existing Curve Warning Sign Rural Horizontal Curves 20 (2005) 2 5 days     51 (2) 52 (3) 1 (1) 1% (1%)
Add Flags to Existing Curve Warning Sign Rural Horizontal Curves 20 (2005) 3 5 days     49 (3) 49 (3) -0.3 (1.3) -0.6% (3%)
Combinational Horizontal Alignment/Advisory Speed Sign Rural Horizontal Curves 20 (2005) 3 5 days     49 (3) 50 (2) 0.2 (1) 0.4% (2%)
Chevron Sign Rural Horizontal Curves 20 (2005) 1 5 days     52 (-) 52 (-) 0 (-) 0% (-)
NARROWING
Add Shoulder Markings to narrow lane Rural Two-Lane Road Through Small Town 3 (2008) 2 12 months     33 (2) 33 (1) 0.5 (1) 2% (2%)
Urban Freeway Exit Ramp 49 (2000) 4 2 weeks     38 (10) 37 (9) -1 (1) -2% (2%)
Add Center Line and Edge Line Rural Main Roads 3 (2008) 2 12 months     34 (1) 35 (1) 1 (1) 2% (2%)
Urban Residential Area 50 (1984) 2 2 weeks     34 (2)Mean 34 (1)Mean 0 (0)Mean 1% (1%)Mean speed
Rural Two-Lane Road Day 52 (2006) 3       63 (2) 64 (3) 1 (4) 2% (7%)
Rural Two-Lane Road Night 52 (2006) 3       66 (4) 65 (3) -1 (0) -1% (0)
Longitudinal Rumble Strips-raised or grooved patterns installed on both inside edges of normal travel lane to narrow effective width Rural Rural High Speed Intersections on Two-lane Roadways 16 (2008) 9 at least 3 months         -4.5 (0.25)  
Road Diet-restripe road to reduce the number of lanes from 4 to 3 Urban Arterial road 41 (1999) 1   24,000   51 (-) 47 (-) -4 (-) -8% (-)
Tubular Chanelizers -three foot high tubes used to create island in center of road Rural Main Roads 3 (2008) 3 12 months 2060   40 (5) 39 (4) -1 (1) -2% (2%)
ACCESS CONTROLS
Half Closure-Physical blockage of one direction of traffic for a short distance on a two-way street Urban   1 (1999) 11   220 to 9540 151 to 9180 30 (4) 24 (5) -6 (4) -20% (12%)
Diagonal Diverter-a barrier placed diagonally across a four-legged intersection, preventing through movement Urban   1 (1999) 7   474 to 2057 177 to 574 28 (5) 27 (5) -1 (5) -5% (17%)
Full Closure-physical street closure resulting in a dead-end Urban   1 (1999) 2   1540 to 1980 850 to 1080 18 (3) 15 (3) -3 (0) -17% (3%)
COMBINATION MEASURES
Gateway Treatment-the combined use of signs, textured pavements, name plates, monuments, landscaping, and/or others placed at the entrance to a neighborhood that helps to communicate a sense of neighborhood identity Rural Main Roads 3 (2008) 3 12 months     46 (6) 44 (6) -2 (2) -5% (4%)
Urban   5 (2004) 1 9 months     30 (-) 28 (-) -2 (-) -7% (-)
Speed Hump + Speed Table Urban   1 (1999) 4       36 (3) 29 (2) -7 (4) -17% (9%)
Speed Hump + Choker Urban   1 (1999) 2   2456 to 3685 2593 to 2931 38 (2) 25 (0) -13 (2) -33% (3%)
Speed Table + Choker Urban   1 (1999) 3       33 (1) 29 (1) -4 (1) -12% (3%)
Speed Table + Center Island Urban   1 (1999) 2   6500 to 8440 6400 to 6780 37 (1) 29 (1) -8 (3) -22% (6%)
Half Closure + Median Barrier(-Median barriers are raised islands located along the centerline of a street and continuing through an intersection so as to block through movement at a cross street.) Urban   1 (1999) 2   10160 to 10320 1120 to 2120 38 (2) 32 (4) -6 (3) -17% (8%)
Transverse Bar + Speed Feedback Sign Rural Main Roads 3 (2008) 3 12 months 830 to 1680   47 (6) 43 (8) -4 (3) -8% (8%)
Speed Hump + Traffic Circle + Gateway Treatment     2 (2005) 2   2017 to 4213 1857 to 4635 32 (1) 25 (3) -7 (2) -22% (6%)
Textured Pavement + Neckdown + Pavement Marking     2 (2005)     3722 to 3792 3603 31 (-) 31 (-) 0 (-) 0% (-)
Edge Marking + Speed Limit Marking Rural Main Roads 3 (2008) 4 12 months     34 (3) 33 (2) -1 (1) -1% (4%)
Rubber Pedestrian Island + In-Roadway Yield to Pedestrian Crossing Sign (R1-6)(-Removable rubber curbing used to create island and concentrate pedestrian crossings at crosswalk.) Rural Resort Area High pedestrian crossing 22 (2002) 2 2 weeks     44 (2) 38 (1) -6 (3) -14% (6%)

Notes:

1) Reference table only includes U.S. studies, except where no U.S. studies on a treatment exist, then international studies are used.

2) Measures within parentheses in the “85%th Speeds” columns represent the standard deviations from the average values.

References:

  1. Ewing, Reid (1999), “Traffic Calming: State of the Practice”, (FHWA-RD-99-135), ISBN 0-935403-36-1, ITE/FHWA. http://www.ite.org/traffic/tcstate.asp#tcsop

  2. Arlington County, VA (2005), “Effectiveness of Traffic Calming Measures in Arlington County”, Table 1. http://www.arlingtonva.us/Departments/EnvironmentalServices/dot/planning/ntc/study/Study05.aspx

  3. FHWA (2008), “Traffic Calming on Main Roads Through Rural Communities”, FHWA Publication No.: FHWA-HRT-08-067. http://www.tfhrc.gov/safety/pubs/08067/index.htm

  4. Marek, John C. and Walgren, Shauna (2000), “Mid-Block Speed Control: Chicanes and Speed Humps”, City of Seattle, WA. http://www.seattle.gov/Transportation/docs/ITErevfin.pdf

  5. Arup Services New York Ltd (2004), “Downtown Brooklyn Traffic Calming Project”, New York City Department of Transportation. http://home2.nyc.gov/html/dot/downloads/pdf/brooklyn_2.pdf

  6. UK DFT (1999), “Traffic calming on major roads: a traffic calming scheme at Costessey, Norfolk”, Traffic Advisory Leaflet 14/99, Department for Transport, UK. http://www.dft.gov.uk/adobepdf/165240/244921/244924/TAL_14-991.pdf

  7. ATSSA (2006), “Low Cost Local Roads Safety Solutions”, American Traffic Safety services Association (ATSSA), Fredericksburg, VA. http://www.cmap.illinois.gov/WorkArea/linkit.aspx?LinkIdentifier=id&ItemID=14624

  8. Fors, C. (2002), “Controlling Community Speeds with Radar Displays”, In Police and Security News, Vol. 18, No. 5.

  9. Ray Godinez (2005), “Stationary Radar Sign Program, Transportation Department”, City of Bellevue, Washington State. http://www.ci.bellevue.wa.us/pdf/Transportation/2005_Radar_Report.pdf

  10. City of Englewood (2007), “Traffic Calming - Recent Accomplishments”, Englewood, Colorado. http://www.englewoodgov.org/Index.aspx?page=649 (accessed 2008).

  11. Bryan J. Katz (2004), “Pavement Markings for Speed Reduction”, Traffic Control Devices Pooled Fund Study (TPF-5-065). http://www.pooledfund.org/documents/TPF-5_065/speed_reduction.pdf

  12. Drakopoulos, A. and Vergou, G. (2003), “Evaluation of the Converging Chevron Pavement Marking Pattern at one Wisconsin Location”, AAA Foundation for Traffic Safety, Washington, D.C. http://www.aaafoundation.org/pdf/chevrons.pdf

  13. Corkle, J., Giese, J.L., and Marti, M.M. (2001), “Investigating the Effectiveness of Traffic Calming Strategies on Driver Behavior, Traffic Flow and Speed”, MN/RC-2002-02. Minnesota Department of Transportation, St. Paul, Minnesota. http://www.lrrb.org/PDF/200202.pdf

  14. Ullman, G.L. and Rose, E.R. (2005), “Evaluation of Dynamic Speed Display Signs”, Transportation Research Record 1918, TRB, pp. 92-97. http://trb.metapress.com/content/3028rr500u381630

  15. Prevedouros, Panos (2000), “Evaluation of in-pavement Flashing Lights on a Six-lane Arterial Pedestrian Crossing”, University of Hawaii at Manoa, Honolulu, HI. http://www.xwalk.com/images/Hawaii_Study.pdf

  16. Vanasse Hangen Brustlin, Inc. (2008), “Two Low-Cost Safety Concepts for Two-Way STOP-Controlled, Rural Intersections on High-Speed Two Lane, Two-Way Roadways”, FHWA Publication No. FHWA-HRT-08-063, Federal Highway Administration, Washington, D.C. http://www.tfhrc.gov/safety/pubs/08063/index.htm

  17. Kittelson & Associates, Inc., etc. (2007), “Guidelines for Selection of Speed Reduction Treatments at High-Speed Intersections”, NCHRP web-only document 124, National Cooperative Highway Research Program, TRB, Washington, D.C. http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_613.pdf

  18. Bretherton Jr., W. M. (2003), “Do Speed Tables Improve Safety?”, Paper presented at ITE 2003 Annual meeting, Seattle, WA. http://www.ite.org/traffic/documents/AB03H5601.pdf

  19. Berger, Wolfgang J. and Martin Linauer (1999), “Speed Reduction At City Limits By Using Raised Traffic Islands”,  Proceedings from the 2nd KFB-Research Conference – Urban Transport Systems, Lund, Sweden. http://www.lth.se/fileadmin/tft/dok/KFBkonf/6Bergerlinauer.PDF.

  20. Vest, Adam and Nikiforos Stamatiadis (2005), “Use Of Warning Signs and Markings to Reduce Speeds on Curves”. The 3rd International Symposium on Highway Geometric Design, Chicago Illinois, United States. http://pubsindex.trb.org/document/view/default.asp?lbid=760638

  21. Parker, Martin. R., Jr.(1997), “Effects of Raising and Lowering Speed Limits on Selected Roadway ections”, FHWA Publication No. FHWA-RD-97-084. http://www.dot.state.oh.us/districts/D01/PlanningPrograms/trafficstudies/SpeedZones/Documents/2hj01!.pdf

  22. Kamyab, Ali, Steve Andrle, and Dennis Kroeger (2002), “Methods to Reduce Traffic Speed in High Pedestrian Areas”, Minnesota Department of Transportation Report No. MN/RC – 2002-18. http://www.lrrb.org/PDF/200218.pdf

  23. Fitzpatrick, Kay, Marcus A. Brewer, and Angelia H. Parham (2003), “Left-Turn and In-Lane Rumble Strip Treatments for Rural Intersections”, Texas Department of Transportation Report No. FHWA/TX-04/0-4278-2. http://tti.tamu.edu/documents/0-4278-2.pdf

  24. Taft, Russ (2001), “School Radar Speed Display Sign Effectiveness Report”, San José Department of Transportation. http://www.forteltraffic.com/uploaded/sanjosereport.pdf

  25. Mattox, James H., III, Wayne A. Sarasua, Jennifer H. Ogle, Ryan T. Eckenrode, and Anne Dunning (2007), “Development and Evaluation of a Speed-Activated Sign to Reduce Speeds in Work Zones”, Transportation Research Board 2007 Annual Meeting CD-ROM. http://www.workzonesafety.org/files/documents/database_documents/07-0015.pdf

  26. Kelly Grant Ash (2006), “Increasing Speed Limit Compliance in Reduced-Speed School Zones”, Master of Science thesis submitted to Brigham Young University. http://contentdm.lib.byu.edu/ETD/image/etd1271.pdf

  27. Pesti, Geza, Patrick T. McCoy (2001), “Long-Term Effectiveness of Speed Monitoring Displays in Work Zones on Rural Interstate Highways”, Transportation Research Board 2001 Annual Meeting. http://www.workzonesafety.org/files/documents/database_documents/00573.pdf

  28. Garden Grove, City of. (2003). “Speed Radar Feedback Sign Study”, City of Garden Grove, California. http://www.forteltraffic.com/needs/download.php?id=205

  29. Chang, Kevin N., Matthew Nolan, and Nancy L. Nihan (2005), “Measuring Neighborhood Traffic Safety Benefits by Using Real-Time Driver Feedback Technology”, Transportation Research Record No. 1922, pp. 44–51. http://trb.metapress.com/content/10j8t56r40433j05

  30. Hawkins, H. Gene, Jr., Matthew A. Sneed, and Cameron L. Williams (2007), “Evaluation of Traffic Control Devices: Third-Year Activities”, Texas Department of Transportation, Report No. FHWA/TX-07/0-4701-3. http://tti.tamu.edu/documents/0-4701-3.pdf

  31. PIRKKO RÄMÄ (1999), “Effects of Weather-Controlled Variable Speed Limits and Warning Signs on Driver Behavior”, Transportation Research Record 1689, pp. 53-59. http://trb.metapress.com/content/t071x61532h5683r

  32. Brewer, Marcus A., Geza Pesti, and William Schneider IV (2006), “Improving Compliance with Work Zone Speed Limits Effectiveness of Selected Devices”, Transportation Research Record No. 1948, pp. 67–76. http://trb.metapress.com/content/q88303792um87557

  33. DeRobertis, Michelle and Raymond D. Chong, School Zone Improvements, Cupertino, CA.  http://www.walkinginfo.org/pedsafe/casestudy.cfm?CM_NUM=44&CS_NUM=27 (accessed May 2009)

  34. Kannel, E.J. and W. Jansen (2004), “In-Pavement Pedestrian Flasher Evaluation: Cedar Rapids, Iowa”, CTRE Project 03-145, Center for Transportation Research and Education, Ames, Iowa. http://www.intrans.iastate.edu/reports/ped_flasher.pdf

  35. Sorrell, Mark T., Wayne A. Sarasua, William J. Davis, Jennifer H. Ogle, and Anne Dunning (2007), “Use of Radar Equipped Portable Changeable Message Sign to Reduce Vehicle Speed in South Carolina Work Zones”, Transportation Research Board Annual Meeting CD-ROM. https://www.workzonesafety.org/files/documents/database_documents/07-3159.pdf

  36. Ritchie, Scott and Mark Lenters (2005), “High Speed Approaches At Roundabouts”, Transportation Research Board National Roundabout Conference, Vail Colorado. http://roadwaystandards.dot.wi.gov/standards/fdm/forms/11-26-030p01.pdf

  37. Waddell, Edmund and James Albertson (2005), “The Dimondale Mini: America’s First Mini-Roundabout”, Transportation Research Board National Roundabout Conference, Vail Colorado. http://onlinepubs.trb.org/Onlinepubs/circulars/ec083/28_Waddellpaper.pdf

  38. Ariniello, Alex J.(2004), “Are Roundabouts Good for Business?”, Transportation Research Board National Roundabout Conference, Vail Colorado. http://ci.golden.co.us/files/roundaboutpaper.pdf

  39. Reddy, Vivek, Tapan Datta, and Satya Pinapaka (2008), “Evaluation of Innovative Safety Treatments Volume 6: A Study of the Effectiveness of In-Roadway Lights”, Florida Department of Transportation. http://cdm266301.cdmhost.com/cgi-bin/showfile.exe?CISOROOT=/p266401coll4&CISOPTR=2489&filename=2490.pdf

  40. Ulfarsson, Gudmundur F., Venkataraman N. Shankar, and Patrick Vu (2005), “The Effect of Variable Message and Speed Limit Signs on Mean Speeds and Speed Deviations”, International Journal of Vehicle Information and Communication Systems, Vol. 1, Nos. 1/2. http://www.inderscience.com/storage/f215111287310694.pdf.

  41. Skene, Michael (1999), “‘Traffic Calming’ On Arterial Roadways?”, Institute of Transportation Engineers Compendium of Technical Papers. http://www.ite.org/traffic/documents/AHA99B08.pdf

  42. Macbeth, Andrew G. (1998), “Calming Arterials in Toronto”, Institute of Transportation Engineers Compendium of Technical Papers. http://www.ite.org/traffic/documents/AHA98C19.pdf

  43. Carlson, Paul J., Mike Fontaine, H. Gene Hawkins, Jr., Kimberly Murphy and Danny Brown (1999), “Evaluation of Speed Trailers at High-Speed Temporary Work Zones”, Transportation Research Board 2000 Annual Meeting. https://tti.tamu.edu/publications/catalog/record_detail.htm?id=15302

  44. Drakopoulos, Alex, Sharad Uprety and Georgia Vergou (2003), “I-43 Speed Warning Sign Evaluation”, Wisconsin Department of Transportation Report. http://www.eng.mu.edu/~drakopoa/web_documents/I_43_sign/Fore_abstract.pdf

  45. Latoski, Steven P.(2009), “Optical Speed Zone for Rural Two-Lane Highways”, Institute of Transportation Engineers Journal, March 2009. http://www.ite.org/membersonly/itejournal/pdf/2009/JB09CA30.pdf

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