Analyzing Hard Shoulder Function of a Four-Lane Expressway for Congestion Caused by an Accident

The study explored using hard shoulders for congestion caused by accidents. The shoulder could serve as managed lanes to alleviate congestion or allow emergency vehicles to pass. Results show that congestion would be much more severe with hard shoulders functioning as emergency lanes compared as additional lanes, while the efficiency of accident handling would be slightly better. Meanwhile, handling accidents promptly is critical for safety and for alleviating traffic congestion. For a comprehensive consideration, it is recommended that after rescue vehicles have arrived at the accident location, the hard shoulder could be used as an additional lane to alleviate the congestion. The mobility could be increased with the proper use of hard shoulders.