A Texas Department of Transportation (TxDOT) project to widen 96 miles of I-35 through central Texas has led to the design of an innovative end-of-queue warning system that reduced crashes by up to 45%.
Frequent temporary nighttime lane closures were inducing queues upstream of the merging taper. (Daytime closures were prohibited.) The queues were of concern for four reasons:
- The corridor is predominantly rural, so drivers do not expect traffic queues, especially at night;
- Lane-closure necessity and locations vary nightly so travelers are unable to develop an expectation of queues;
- Contractors were using all available right-of-way for construction activities, so queue-warning equipment could not be easily positioned and left until needed; and
- The corridor is heavily used by large trucks, which increases the severity risk of any end-of-queue crashes.
The end-of-queue warning system used on the I-35 project consisted of two components: the portable work-zone queue detection and warning system and portable rumble strips.
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