# Presentation: 367558

## 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 85th 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
- Did truck operators actually receive the message?
- 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
- This is the Iowa DOT.  Slow-moving paint operation in the right lane of north bound Interstate 35.  Please use caution.
- 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
- 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.
- 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
- How years of profession driving do you have?
- Do you have a CB?
- Did you see the paint crew and, if so, what was your first alert?
- Did you hear the CB alert?
- Did you think the alert was effective?
- 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 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