3 Speed Management
3.1.4 Sandstone Mountain Downhill Truck Warning System – West Virginia
Impetus for the Activity
The problem that sparked the West Virginia Division of Highways to consider a technological treatment was a large number of runaway truck incidents on a long steep downgrade, resulting in runaway ramp uses or serious crashes. Incidents were occurring several times a month. A technological treatment was considered because the Division of Highways had applied every conventional treatment that they thought might be appropriate.
Criteria for System Selection (Hardware and Software)
The Division of Highways reviewed alternate systems, followed by narrowing down the candidates to finally select the concept that was the “best fit” for the site.
Description of the System
The system was installed during late 1998 and is currently active. The system was installed with the expected result of a reduction in runaway incidents and mishaps.
The objective of the system is to provide drivers of larger, heavier vehicles with a vehicle-specific advisory speed, based on gross weight and number of axles, at which they can safely negotiate Sandstone Mountain.
The system is deployed at the top of a long, steep downgrade on a rural Interstate Highway (I-64). The system consists of two changeable message signs (CMSs), driven by a computer that obtains weight and classification data from loops and piezo sensors in each lane. Every vehicle is weighed and classified, and each vehicle is an individual record. The system uses a table lookup system for a suggested speed choice, and an advisory speed message is displayed on a CMS. The message is updated for every vehicle passage. The table used is based on an adaptation of the Grade Severity Rating System.
System Performance
Weather and a “clean” electric power supply are two factors that affect system performance. The system has not yet performed satisfactorily, but now appears to be working. There have been no formal tests of system performance.
System Effectiveness Evaluation
The effectiveness of the system has not been formally evaluated because it has not been reliable for enough time.
Perceived “Hot Spots” for Rural ITS Deployment
Similar steep, long downgrades are perceived “Hot Spots” for deployment of rural ITS systems such as this one.
Obstacles and Lessons Learned
The biggest obstacle was getting all of the electronics to work. There were defective parts in the system, which proved very difficult to isolate and identify. West Virginia Division of Highways had a 2-year warranty on the system; they now wish that it were longer.