Studies to Improve the Management of Regulatory Speed Limits in Texas Work ZonesAuthor/Presenter: Finley, M.D.; Theiss, L.D.; Trout, N.D.; Ullman, G.L.
This report describes the methodology and results of analyses performed to (1) improve existing procedures on establishing and managing work zone speed limits, and (2) evaluate new technologies and strategies that can be used to better manage work zone speed limits. Field studies indicated that motorists reduce their speed adjacent to most of the work zone conditions currently used in Texas to justify reduced work zone speed limits; however, the amount of the speed reduction is dependent upon the normal non-work zone operating speed of the roadway. Based on the field study findings, researchers recommended a 5 mph maximum speed reduction for shoulder activity and lane encroachment conditions. A 10 mph maximum speed reduction is still warranted for lane closures and temporary diversions. Speed limit reductions should be discouraged on roadways with existing speed limits less than 65 mph for all conditions except lane closures when workers are in a closed lane unprotected by barrier and only a single travel lane remains open. Short term work zone speed limits are reduced speed limits that are posted only when work activity is present. When the work activity is not present, the short term work zone speed limit signs should be removed or covered; thereby allowing the legal speed limit for that segment to revert back to the normal non-work zone speed limit. The major challenge with short term work zone speed limits is the daily install/remove or uncover/cover process. Field studies and motorist surveys verified that electronic speed limit (ESL) signs and static flexible roll-up work zone speed limit signs are easily implemented, effective at reducing speeds, and understood by motorists. Based on these results, researchers recommended the use of ESL signs and static flexible roll-up work zone speed limit signs. Additional findings from all of the studies and detailed recommendations are discussed in the report.