In current freeway work zones, lane closure operations employ both left-lane and right-lane closure layouts. The safety implications of these two layouts are not well understood. First, the safety implications of work zone left-lane closures and right-lane closures for three-lane freeway segments are assessed. Lack of safety is measured on the basis of two traffic-flow characteristics: uncomfortable deceleration and speed variance. These characteristics are obtained for specific work zone layouts by using microlevel simulation (INTEGRATION). Second, an alternative, more channelized lane closure layout is proposed and its safety benefits are compared with those associated with the current leftlane and right-lane closures. The results of the simulation suggest that the proposed channelized lane closure layout results in lower values of uncomfortable deceleration and speed variance and thus improves safety for the three-lane freeway segment.