Study Details
Study Title: Crash Analysis of Work Zone Lane Closures with Left-Hand Merge and Downstream Lane Shift
Authors: See et al.
Publication Date:JAN, 2009
Abstract: The Arkansas State Highway and Transportation Department (AHTD) began the implementation of the "Iowa weave", or lane closure with a left-hand merge and lane shift for their Interstate Rehabilitation Program (IRP) in the spring of 2000. The main objective of incorporating this technique was to speed up the construction progress, while improving traffic safety. It was the AHTD's expectation that by providing consistent lane closures (always merging traffic to the left) they would provide greater expectancies and compliance by drivers, resulting in fewer crashes. Although efforts have been made to analyze the Iowa weave, the safety implications of this weave pattern on rural four-lane Interstates section, where work zone lane closures are generally situated is not well documented. To account for this, an analysis on the correlation of lane closure strategies and work zone crashes along with other influential variables was examined. This study was aimed at quantifying the safety effects of the Iowa weave as opposed to conventional right-lane closure on rural freeway segments on the basis of actual crash experience. The findings of the analyses were organized by: 1) crash frequency; 2) crash rates; and 3) crash severity. While changes in the overall number of work zone crashes and the crash severity were found to be not significantly different between the Iowa weave and the conventional right-hand closure, it was found that the Iowa weave had a crash rate 46 percent lower than the conventional right-hand closure, which was a statistically significant finding.
Study Citation: See, C.F., S.D. Schrock, and K. McClure, "Crash Analysis of Work Zone Lane Closures with Left-Hand Merge and Downstream Lane Shift." TRB 88th Annual Meeting Compendium of Papers CD-ROM. Washington, D.C., (2009).
CMFs Associated With This Study
Category: Work zone
Countermeasure: Implement left-hand merge and downstream lane shift (Iowa weave)
| CMF | CRF(%) | Quality | Crash Type | Crash Severity | Roadway Type | Area Type |
|---|---|---|---|---|---|---|
| 0.54 | 46 |  | All | All | Principal Arterial Interstate | Rural |
| 2.24 | -124 | | All | K,A,B,C | Principal Arterial Interstate | Rural |
