This work contributes to the operational design of dynamic HOV lanes on French urban freeways. We propose a framework to estimate the acceptable dynamic maximal speed of the HOV lane, knowing the current origin speed. The aim is to ensure safety of lane changes while maintaining an acceptable duration of the period before gap acceptance. It is recognized that the longer the time a driver waits before accepting a gap, the lower he/she places the threshold for next gap acceptance. That may lead to inappropriate behaviors, such as unsafe lane changes. The key variables for lane changing realization are speeds and headways on origin and target lanes (estimated here with individual loop data). Both variables play an important role in lane change maneuver safety. We present in this paper two lane change realization models combining simple rules and observed data, one pessimistic and one optimistic. From this, we determine the maximal and minimal boundaries of two indicators: the number of rejected gaps and the waiting time to safe lane change. Those indicators lead to an appraisal of lane change realization safety. The results tend to show that a speed regulation lower than usual speed may increase safety while not degrading the service provided by this lane to its specific users. Having in mind the perspective of lanes dedicated to connected automated cruise control vehicles, we extend the proposed method to provide an analysis of the impact of uniforms inter-vehicular time gap on lane change safety.