Updated Capacity Values for Short-Term Freeway Work Zone Lane Closures

Recommendations on estimating the capacities of short-term freeway work zone lane closures are presented. The recommendations are based on 45 hr of capacity counts at 33 work zones in Texas between 1987 and 1991. These new data indicate average capacities for short-term freeway work zone lane closures from three lanes to one lane and from two lanes to one lane that are significantly higher than older values reported in the 1985 Highway Capacity Manual. A base capacity value of 1,600 passenger cars per hour per lane is recommended for all short-term freeway work zone lane closure configurations. Adjustments are recommended for the effects of the intensity of work activity, the percentage of heavy vehicles in the traffic stream, and the presence of entrance ramps near the beginning of the lane closure. It is recommended that the new base capacity value and adjustments be used in lieu of the current procedures in the 1985 Highway Capacity Manual.