Speed Reduction Strategies Ali Kamyab, Research Scientist Tom Maze, Professor CTRE, Iowa State University

Started in 1999 to research, test and evaluate work zone safety technology Originally the states of Iowa, Kansas, Missouri, and Nebraska 2001 Wisconsin joined Expecting Minnesota and Georgia to become members soon

Iowa’s program Focused on rural work zones and on speed reduction Initially focused on testing technology to moderate speeds (tactical level) Next provided a broader look at strategies (strategic level) Policy actions Technology applications Regulatory/enforcement strategies Currently exploring design, traffic management, planning, and enforcement issues

2000 synthesis of speed reduction strategies Regulatory and advisory speed limit signs Lane width reduction Flaggers Police enforcement Drone radar Speed display monitoring Rumble strips Optical speed bars

Report’s main conclusion “ None of the techniques individually are capable of reducing vehicle speeds to the desired level. Effective speed reductions will probably involve some combination of technologies and policies.”

Regulatory and advisory signs Advisory signs – little impact Increased frequency of signs – no impact Regulatory – impact when enforced Regulatory signs with strobes – some impact

Lane width reduction It matter how the lane width reduction is done Cones – little impact Concrete barriers – more impact Lane width reduction – reduce speed by 0 – 16%* Lane width reduction – may have minimal impact** *Richards, S.H., R.C.Wunderlich, and C.L. Dudek, “Controlling Speeds in Highway Work Zones, TTI, 1984 **Benekohal, R.F., Kastel, L.M., and M. Suhale, “Evaluation of Work Zone Speed Control Techniques, TRR 1035, 1985

Flagging Significant impact* Improves with training of flagger 7-13 mph on rural interstates 10 – 16 mph on two lane roads 13 mph on urban arterial streets Labor intensive Fatiguing * Richards, S.H., R.C.Wunderlich, and C.L. Dudek, “Controlling Speeds in Highway Work Zones, TTI, 1984

Enforcement Significant impact Stationary squad car – reduce 6 to 22 percent* Circulating patrol car – 3 to 5 percent speed reduction* * Richards, S.H., Wunderlich, R.C., and C.L. Dudek, “Field Evaluation of Work Zone Speed Control Techniques, TRR 1035, 1985

Drone radar, Speed monitor display, and Rumble strips Drone radar Minimal impact Speed monitor displays Impact significant at the beginning Impact tends to wane with time Rumble strips Reduction of average speed by few mph

Optical speed bars Reduce the 85 th percentile speed and the mean speed Significant reduction of the standard deviation of speed Source Meyer, E., “A New Look at Optical Speed Bars,” ITE Journal November, 2001

Conclusions All technology provides some benefits The impact of all technology diminishes with time Enforcement’s impact is consistent with time Reduction continues for a short period even after enforcement leaves

Results of state DOT survey (36 agency responses)

Results of second state DOT survey 28 state responses

Results of stepped up enforcement experiment

Iowa’s Evaluation of the Wizard CB Alert System

Why Rural Focus? Increased frequency of construction Increased congestion Aggressiveness of drivers

Motivation for Iowa DOT Concern Safety (worker and motorist) Rural congestion Efficiency of operations

Wizard CB Alert System Designed and patented by Highway Technologies, Inc. Built and marketed by TRAFCON Industries, Inc. Developed at the request of the Pennsylvania Department of Transportation

CB warning for upcoming delays Focuses on trucks – most common users of CBs Typically heavy trucks represent 30% or more of the traffic Attempts to moderate speed before reaching work zones

Evaluation case study Moving work zone I-35 paint stripping crew Warning on channel 19 Work zone characteristics Moving at 25 mph Four to five vehicles spread over about one-mile Lead vehicle is stripping truck Trailing pick-up with flashing board “CENTERLINE/EDGELINE PAINT AHEAD”

Wizard CB alert system experiment Broadcast at 30- second interval Broadcast on channel 19 (only one channel) Varied message depending on user response

Evaluation questions 1. Did truck operators actually receive the message? 2. Did the message effectively alert the drivers? Data collection challenges Moving work zone – making speed measurement difficult No means to stop truck operators to question them

Two proxy measures of effectiveness Questionnaire administered to truck operators upstream at rest area Monitor CB channel for truck operator comments (in tailing vehicle)

Modifying warning 1.This is the Iowa DOT. Slow-moving paint operation in the right lane of north bound Interstate 35. Please use caution. 2.This is the Iowa DOT. Slow-moving paint operation in the right lane of northbound Interstate 35 – milepost 160 to milepost 170. Please use caution.

Modifications continued 3.This is the Iowa DOT. Northbound drivers on Interstate 35, you are approaching a slow-moving paint crew in the right lane. Please use caution. 4.This is an Iowa DOT road work alert. Northbound drivers on Interstate 35, you are approaching a slow-moving paint crew in the right lane. Please use caution.

Evaluation results CB Radio Comments Operators expressed their disapproval over the work zone itself Many noticed the new and different message – majority were positive. “That’s the first time I’ve ever heard anything like that. I wish everyone would do that. It’d make things a lot easier” “Get off my radio. You need to get a regular radio station and warn those four wheelers.”

Rest Area Survey 1.How years of profession driving do you have? 2.Do you have a CB? 3.Did you see the paint crew and, if so, what was your first alert? 4.Did you hear the CB alert? 5.Did you think the alert was effective? 6.Was the message annoying?

Rest area results 94 total interviews 88 (94%) had CBs Of those with CBs, 70 were tuned to channel 19 (80%) 59 of those with CB tuned to channel 19 passed the paint crew (63%)

What alerted you first? CB Alert Message24 (40%) Lights on Trucks14 (24%) Signs10 (17%) Arrow Board 7 (12%) Other Truck Drivers 4 (7%) Total59(100%)

Out of the 59, 44 said they heard the CB message (75%) Out of the 44, 39 (89%) thought it was effective Out of 44, 1 said the message was annoying

Example Comments “This could save accidents from happening” “This alerts everybody. It’s a good idea.” “Neat idea! More states should use this!” “A good idea, but sooner (warning) would be more helpful.”

Conclusions No hard data was available System appears to be effective –41% stated CB alert was their first warning –Generally popular with truck operators How the warning is phrased is important

Acknowledgements This work was sponsored through Midwest States Smart Work Zone Deployment Initiative and sponsored by the Iowa Department of Transportation

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