Recommendations on estimating the capacity of short-term freeway work zone lane closures are presented. The recommendations are based upon 45 hours of capacity counts at 33 different work zones between 1987 and 1991. These new data indicate average capacities for short-term freeway work zone lane closures from 3 to 1 lanes and from 2 to 1 lanes that are significantly higher than older values reported in the 1985 Highway Capacity Manual. A base capacity value of 1,600 pcphpl is recommended for all short-term freeway work zone lane closure configurations.