The National Transportation Safety Board is investigating an incident at Midway Airport.

A Southwest Airlines plane slid off the end of the runway Tuesday, stopping just short of a barrier separating the airport from the street. Offials say none of the 140 passengers or crew was injured.

The plane skidded off the runway at about 1:35 p.m. Tuesday afternoon. There were reports of heavy rain at the time of the landing. Passengers were taken off the plane and bused back to the terminal.

Joe Schwieterman follows the airline industry at DePaul University. He said Midway has gotten safer in recent years.

“They’ve done some facility modifications at the end of the runways, installed some of the safety buffering for an aircraft to overrun the runway, it’s easier for them to stop at some of the permeable surfaces they put in there,” he said.

But Schwieterman said despite the updates, Midway will always have challenges like Tuesday’s because the runways are too short.

In 2005 a plane slid off the runway at Midway and crashed onto the street, killing one person.