Vehicle-to-vehicle (V2V) cooperative systems that alert drivers to roadway hazards are increasingly being studied to improve freeway safety and should be implemented by automakers in the near future. However, the impact of these systems on traffic operations has not been assessed. A methodology is described for modeling driver response to lane-blocking freeway incidents with and without the use of V2V hazard alerts. Driver response to assumed incidents and V2V safety messages is modeled microscopically with the NGSIM oversaturated freeway flow algorithm. The simulation results show how the V2V alerts could influence freeway traffic and provide initial estimates of their benefits.