Evaluating Alternative Operations Strategies to Improve Travel Time ...

SHRP 2 L11: Final Appendices
• Customer Satisfaction: An evaluation of Arizona 511 telephone traveler information system found that more than 70 percent of
users surveyed were satisfied with the enhancements (1)
In Houston, real-time travel time information posted on Dynamic Message Signs (DMS) influenced drivers’ route choice. Eightyfive
(85) percent of respondents indicated that they changed their route based on the information provided. (Of these respondents,
66 percent said that they saved travel time as a result of the route change, 29 percent were not sure). Overall, drivers were primarily
interested in seeing incident and travel time information (5).
Road Weather Information Systems (RWIS)
• Safety: A wet pavement detection system In North Carolina on I-85 yielded a 39 percent reduction in the annual crash rate under
wet conditions (1).
Anti-icing systems deployed on bridges in Utah, Minnesota, and Kentucky found crash reductions from 25% to 100%. (3).
In Vantage, Washington, the deployment of an automated anti-icing system on I-90 was projected to eliminate up to 80 percent of
snow and ice related crashes (5).
A Variable Speed Limit (VSL) system implemented along I-75 in Tennessee to control traffic during foggy conditions, and close
the freeway if necessary, has dramatically reduced crashes. While there had been over 200 crashes, 130 injuries, and 18 fatalities on
this highway section since the interstate opened in 1973, a 2003 report noted that only one fog-related crash occurred on the
freeway since installation of the system in 1994 (5).
• Mobility: Signal timing plans implemented in Minnesota to accommodate adverse winter weather resulted in an 8% reduction in
delay (1).
In Salt Lake City, Utah, the use of 511 to provide weather information resulted in a reduction of peak-period late arrivals by 11.8%
(4).
In Finland, a Road Weather Information Systems (RWIS) that automatically communicated actual and forecast data to road
maintenance personnel was estimated to save an average of 23 minutes per deicing activity and improve traffic conditions. (5)
• Efficiency: The benefit-to-cost ratios in Oregon for two automated wind warning systems were 4.13:1 and 22.80:1. (1)
In Salt Lake City, Utah, staff meteorologists stationed at a Traffic Operations Center (TOC) provided detailed weather forecast data
to winter maintenance personnel, reducing costs for snow and ice control activities, and yielding a b/c ratio of 10:1. (2)
Benefit-to-cost ratios for Road Weather Information Systems (RWIS) and anti-icing strategies range from 2:1 to 5:1 (5).
A Kansas DOT study found that the application of AVL to highway winter maintenance vehicles could result in a benefit-to-cost
ratio ranging from at least 2.6:1, using conservative assumptions, to 24:1 or higher based on moderate assumptions (5).
ADDITIONAL DESCRIPTION AND QUANTITATIVE BENEFITS OF TRAVEL-TIME RELIABILITY STRATEGIES Page F-24