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Evaluation of the Fredonyer Summit Ice Curve Warning System – Showcase Evaluation #14

Project #: 4264541
Start Date: 01/01/2002
End Date: 03/30/2007
Status: Completed

One challenge with rural travel is weather producing adverse driving conditions at isolated locations. This adverse weather can increase the possibility for accidents resulting in potential injury and loss of lives. The cost of traditional solutions, such as redesign of the roadway to attempt to mitigate the effects of weather on specific locations can be financially prohibitive, especially when the problems tend to be seasonal in nature. Accordingly, solutions using intelligent transportation systems (ITS) may be an attractive and cost-effective method of improving safety at these locations. California State Route 36 in the vicinity of Fredonyer Summit in Lassen County has a high accident history, resulting primarily from crashes when the pavement is icy on two tight curves. Icy pavement partly results from heavy snowfall, but also from the effects of shading from adjacent hills and tree coverage. To provide additional warning of ice and snow conditions at these two locations, Caltrans is installing two Road Weather Information Systems (RWIS) and four extinguishable message signs (EMS) with flashing beacons mounted on lightweight sign structures preceding the curves. The RWIS will continuously monitor road surface conditions and activate the flashing beacons and EMS to warn motorists when there is ice on the road. The RWIS will also provide information to Caltrans maintenance personnel that will allow them to treat and maintain the road with greater efficiency. This project seeks to evaluate the effectiveness of this system in improving traveler safety in the vicinity of the summit. Data that will be used to support conclusions include accident data, speed data, motorist surveys, maintenance staff surveys, and a technology assessment. In addition to quantifying the effectiveness of the Fredonyer system, this project will provide recommendations as to how such systems should be deployed in the future.


The objective of this evaluation will be to determine if the icy curve warning system to be deployed by the California Department of Transportation (Caltrans) near Fredonyer Summit on State Route 36 is effective in improving traveler safety. Specifically, the evaluation intends to answer the following questions:§ Are motorists responding to the information presented to them?§ Does the system function as promised from a technological standpoint – e.g. continuous monitoring of conditions, automatic warning of motorists, communication of RWIS data to maintenance staff?§ Does the RWIS provide information to maintenance personnel that helps them to prepare and maintain the road with greater efficiency?


  • Chris Strong
    Chris Strong