The US Department Of Transportation (DOT) has issued new rules designed to help riders stay safe when bus crashes occur. The regulations issued on Monday are intended to mitigate “occupant ejection” and include fresh performance requirements for vehicle windows and roof panels.

The new rules involve propelling an “impactor” weighing 57 pounds towards a bus window at 13.4 mph and passing marks will be awarded to those that withstand an impact by projectiles measuring up to four inches or displace less than 6.9 inches, if the test glass has been pre-broken.

In addition, emergency exit latches for all commercial vehicles must now be designed to not hinder an escape as well as being able to be used after a crash.

The National Highway Traffic Safety Administration (NHTSA) stipulated in 2013 that all new buses must include seat belts before directing manufacturers a year later to improve their vehicles’ structural integrity so that windows and emergency exits do not fail and become “ejection portals” during a rollover.

In 2010, 36 passengers travelling to the Mohegan Sun Casino in Uncasville, Connecticut, from New York City were injured, some critically, when their bus hit a guard rail and flipped in the snow on Interstate 95 in the nearby town of Madison, while 15 were killed the next year returning from the same giant casino after their vehicle careened off a roadway in The Bronx.