Couplings give US drawbridge a lift after it fails to close

摘要

When a busy drawbridge in the US failed during a holiday weekend, officials decided that it needed a new motor drive system. As part of the project, a backup drive was installed, using electric clutch couplings to ensure that traffic would keep moving, even if the primary drive failed. The River Grand is the longest river in the US state of Michigan and one of three major tributaries of Lake Michigan. It is a busy route for shipping, so any bridge less than 60ft (18.3m) above the water must open and close in accordance with US Coast Guard requirements. The US 31 bridge that spans the river at Grand Haven is one of the busiest in the state, with an average of 60,000 vehicles crossing it every day - rising to 120,000 during busy weekends and holidays.