Amtrak engineers are trying to determine what caused a New Jersey river bridge to get stuck, suspending train traffic.
It took more than three hours before trains could cross the Portal Bridge on Wednesday night.
There were no problems during Thursday morning's rush.
Amtrak spokesman Cliff Cole says the bridge, which was built by the Pennsylvania Railroad and opened in 1910, is prone to failure.
Cole says Amtrak is trying to get money to replace the span.