A project on I 75 in Whitley and Laurel Counties during the 1986 construction season involved numerous lane closures associated with spot pavement replacement and joint sealing. Traffic congestion associated with heavy volumes and late merges resulted in the use of the following traffic control devices to supplement standard lane closure devices; 1) variable message signs, 2) supplemental lane closure warning signs, and 3) rumble strips placed in the lane to be closed in advance of the taper.

Results showed a decrease in the percentage of traffic in the lane to be closed with each successive traffic control device in addition to the standard lane closure devices. There was a general decrease in speeds as traffic approached the taper. The percentage of trucks in the lane to be closed was lower than the percentage in the open lane when the closure was a left lane. Hourly traffic volumes observed in this study (800 to 1,300 vph) did not appear to influence the percentage of traffic in the lane to be closed. The percentage of trucks in both lanes (8.5 to 14.7 percent) did not influence the percentage of traffic in the lane to be closed.

Recommendations from the study included the following: 1) supplemental signs for all long-term closures in high-volume, high-speed, four-lane roadways; 2) variable message signs when one-way hourly volumes exceed 1,000 (ADT exceeds 20,000); and 3) application of rumble strips when other devices do not reduce late merges and there is excessive congestion.

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