Speed Reduction Strategies Ali Kamyab, Research Scientist Tom Maze, Professor CTRE, Iowa State...
-
Upload
meagan-chandler -
Category
Documents
-
view
217 -
download
0
Transcript of Speed Reduction Strategies Ali Kamyab, Research Scientist Tom Maze, Professor CTRE, Iowa State...
Speed Reduction Strategies
Ali Kamyab, Research ScientistTom Maze, ProfessorCTRE, Iowa State University
Started in 1999 to research, test and evaluate work zone safety technologyOriginally the states of Iowa, Kansas, Missouri, and Nebraska
2001 Wisconsin joinedExpecting Minnesota and Georgia to become members soon
Iowa’s programFocused on rural work zones and on speed reductionInitially focused on testing technology to moderate speeds (tactical level)Next provided a broader look at strategies (strategic level)
Policy actionsTechnology applicationsRegulatory/enforcement strategies
Currently exploring design, traffic management, planning, and enforcement issues
2000 synthesis of speed reduction strategies
Regulatory and advisory speed limit signsLane width reductionFlaggersPolice enforcementDrone radarSpeed display monitoringRumble stripsOptical 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 impactIncreased frequency of signs – no impactRegulatory – impact when enforcedRegulatory signs with strobes – some impact
Lane width reductionIt matter how the lane width reduction is done
Cones – little impactConcrete 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 flagger7-13 mph on rural interstates10 – 16 mph on two lane roads13 mph on urban arterial streets
Labor intensiveFatiguing
* Richards, S.H., R.C.Wunderlich, and C.L. Dudek, “Controlling Speeds in Highway Work Zones, TTI, 1984
EnforcementSignificant impactStationary 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 radarMinimal impact
Speed monitor displaysImpact significant at the beginning Impact tends to wane with time
Rumble stripsReduction of average speed by few mph
Optical speed barsReduce the 85th percentile speed and the mean speedSignificant 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 benefitsThe impact of all technology diminishes with timeEnforcement’s impact is consistent with time
Reduction continues for a short period even after enforcement leaves
Results of state DOT survey (36 agency responses)
Applicable
No Yes Effective Ineffective
Partially Effective
No Information
Regulatory signs 6 28 2 7 10 9 Advisory signs 26 8 2 0 3 3 CMS 16 18 4 2 5 7 Police enforcement 8 26 18 0 5 3 Ghost police car 32 2 1 0 1 0 Flaggers 32 2 2 0 0 0 Speed display 28 6 2 1 2 1 Drone radar 28 6 2 1 2 1 Rumble strips 33 1 0 0 1 0 Lane narrowing 31 3 2 0 0 1 Pavement markings 33 1 0 0 0 1 HAR 32 2 0 0 1 1
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 constructionIncreased congestionAggressiveness of drivers
Motivation for Iowa DOT Concern
Safety (worker and motorist)Rural congestionEfficiency of operations
Wizard CB Alert SystemDesigned 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 delaysFocuses 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 studyMoving 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 intervalBroadcast on channel 19 (only one channel)Varied message depending on user response
Evaluation questions1. Did truck operators actually receive the
message?2. Did the message effectively alert the
drivers?
Data collection challengesMoving work zone – making speed measurement difficultNo means to stop truck operators to question them
Two proxy measures of effectiveness
Questionnaire administered to truck operators upstream at rest areaMonitor 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 continued3. 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 resultsCB 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 Survey1. 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 interviews88 (94%) had CBsOf 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 Message 24 (40%)Lights on Trucks 14 (24%)Signs 10 (17%)Arrow Board 7 (12%)Other Truck Drivers 4 (7%)
Total 59 (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
Helikite