Progress Report: July 2008
The goal of this research is to develop reliable estimates of the safety effectiveness of safety improvements identified as strategies in the National Cooperative Highway Research Program (NCHRP) Report 500 Guides through scientifically rigorous before-after evaluations of sites within the U.S. where these strategies have been implemented. A target of 20 strategies in four phases will be used in the study totaling $4.38 million for a period of 6 years. The progress for each phase is stated below.
Phase I - Retrospective Evaluation
Evaluations include following strategies:
1) STOP Signs with Increased Retroreflectivity
2) Flashing Beacons
3) STOP AHEAD Pavement Markings
4) Two-Way Left-Turn Lanes
Status:
The Phase I evaluations are complete. All four studies of Phase I were published by Federal Highway Administration (FHWA) in April 2008. Please see the Publications (Web group: please link to the new Publications page) page for the reports.
Transportation Research Board (TRB) presented and will publish the following studies:
1) Flashing Beacons
2) STOP AHEAD Pavement Markings
3) Two-Way Left-Turn Lanes in 2008 TRB annual meeting
Phase II - Retrospective Evaluation
Evaluations include following strategies:
1) Offset Left-Turn Lanes,
2) Advance Street Name Signing
3) Curve Treatments (which replaced Dual Application of Rumble Strips)
4) Lane-Width/Shoulder-Width Combinations
Status:
Due to delay in completion of the installation of Dual Application of Rumble Strips, FHWA replaced the Dual Application of Rumble Strips with the Evaluation of Curve Treatments. There were two more reasons behind this decision
Curve Treatment strategy in Connecticut is a uniform multistrategy curve treatment at 47 sites (Connecticut Department of Transportation installed chevrons with fluorescent yellow sheeting, post-mounted delineators, and upgraded warning signs in the curve area standard fluorescent yellow (FY) sheeting). This treatment is very much inline with Phase III, except this is a retrorespective treatment.
The Low-Cost Safety Phase IV simulation project already underway also deals with the curve treatments with chevrons and post-mounted delineators. The Connecticut curve treatment will complement the simulation study.
The contractor has submitted draft reports for the following Phase II strategies. The drafts presently are being reviewed by subject matter experts.
1) Lane Width/Shoulder Width Combinations
2) Offset Left-Turn Lanes
3) Advance Street Name Signings
4) Evaluation of Curve Treatments
Phase III - Prospective Evaluations
In the annual Technical Advisory Committee Meeting in 2007, “Run-of-Road” (ROR) strategies were among the highest rated (balloting process) for evaluation in the Phase III of the Low-Cost Safety pooled fund study (PFS). The ROR countermeasures are the most comprehensive strategy in all phases (I-IV) of the Low-Cost Safety PFS. These sets of strategies will be based on the NCHRP Report 500, Volume 6: A Guide for Addressing Run-Off-Road (ROR) Collisions. (Web group: link to http://safety.transportation.org/guides.aspx?cid=27) Volume 6 states that to reduce the number of ROR fatality crashes, important objectives are to:
- Keep vehicles from encroaching on the roadside.
- Minimize the likelihood of crashing into an object or overturning if the vehicle travel beyond the shoulder of the road.
- Reduce the severity of crashes.
Status:
- For this “build-to-evaluate” phase, FHWA selected multistrategy ROR countermeasures and proposed possible sets of strategies for installation by volunteer States for the purpose of evaluations.
- Iowa, Kansas, Florida, Virginia, and Kentucky volunteered to build these ROR countermeasures for evaluation of sets of safety countermeasures.
- Volunteer States have reviewed and approved the general concept for this phase.
- Volunteer States are in the process of data collection and data analysis for selection of sites and their corresponding sets of ROR countermeasures (uniform sets of strategy per State.)
- Four-out-of-five volunteer States have provided 5 to 7 years worth of crash data to FHWA for evaluation and independent analysis.
- At present, FHWA is independently organizing and evaluating crash data for volunteer States (evaluation of Virginia and Kansas data have been completed.)
- The contracting process for Phase III is completed and is in the final stages of approval by FHWA. (Approval is expected in the summer of 2008.)
Phase IV - Simulation
The simulation phase evaluations are conducted in the Turner-Fairbank Highway Research Center's Human Centered Systems Laboratories, and it has two parts as described below.
Part1- The low cost safety improvements for curves
The following safety countermeasures are all designed to enhance the visibility of curves at night.
- Edge lines and center lines
- Chevrons
- Post-mounted delineators
- Light-emitting-diode- (LED) mounted delineators
Part 2- The low cost safety improvements for small towns
The following safety countermeasures are all designed to slow traffic down while driving through small towns.
- Bulb-outs
- Chicanes
- Medians
Status:
- Work plans are complete for this phase.
- Development of software road simulations are in progress (near completion) for the above countermeasures.
- The driving simulation data collections are expected to be completed by September of 2008.
- The driving simulation data analysis is expected to be completed in July of 2009.
