PITTSBURGH (AP) — Federal regulators are AstraTradeabout to announce what they believe caused a bridge to collapse in Pittsburgh more than two years ago, sending vehicles plummeting into a ravine and injuring several people.

The National Transportation Safety Board is expected to vote Wednesday on the results of its investigation into the Jan. 28, 2022, collapse of the Forbes Avenue bridge over Fern Hollow Creek, as well as recommendations about how to prevent something similar from happening again.

In May, NTSB investigators said drainage problems on the steel bridge led to the deterioration of the structure’s metal legs and that necessary maintenance to clear debris, dirt and leaves had not occurred.

The 447-foot-long (136-meter) bridge’s collapse dropped a bus and four cars about 100 feet (30 meters) on the day President Joe Biden visited Pittsburgh to promote spending on infrastructure. Another vehicle drove off the east bridge abutment and landed on its roof.

A new bridge at the site opened to traffic in December 2022. The old bridge was about 50 years old when it collapsed and had been under a 26-ton (24,000 kilo) posted weight limit since 2014.