Passengers on overnight bus journeys in Japan will likely get a little more sleep from Friday, after a new regulation was introduced requiring a relief driver to be present on long-haul expressway night buses.

The regulation, introduced in the wake of a tragic bus accident in April, will reassure travelers who may have been apprehensive about using overnight bus services with only one driver.

But the rule has also prompted roughly a third of chartered bus firms to stop offering expressway services as part of a shakeup of an industry in which intense competition appears to have driven companies to flout safety regulations in favor of cost-cutting.

Highway buses are considered a cheaper alternative to bullet trains and airplanes for long-distance travel in Japan, where transportation can come at a hefty price. But the accident in April, which killed seven passengers and injured 39, has refocused attention on the industry's safety standards.

A government report released Wednesday revealed that out of 298 chartered bus companies surveyed, a shocking 84% were violating bus-safety regulations.