U.S. Sen. Dick Durbin (D-Ill.) has asked Federal Railroad Administrator Ronald Batory to work with freight railroads around the Chicago area to ensure Amtrak’s on-time performance improves in Illinois and around the country.

In a letter to Batory sent last week, Durbin noted that Amtrak’s Chicago-Champaign-Carbondale route continues to be “one of the worst performing routes” in the country.

Additionally, Amtrak’s Illini and Saluki routes are consistently delayed by CN‘s freight interference and the ongoing speed restrictions that the Class I put in place in 2015, Durbin wrote.

“Freight interference continues to be the main driver of passenger rail delays on this route and routes across the country,” the letter stated. “Canadian National (CN) in particular has a long history of holding up Amtrak trains and holding back investments that could improve passenger and freight service in downstate Illinois. The [Federal Railroad Administration] must do more to improve Amtrak on-time performance by practicing rigorous oversight of railroads who fail to live up to their obligations under the law.”

Durbin also noted that current speed restrictions along 200 miles of the Chicago-Champaign-Carbondale route were put into place as a safety precaution in 2015 after repeated mechanical issues on the route.

Since then, little progress toward an agreement has been made between CN and Amtrak to resolve the issues so that the speed restrictions can be lifted, according to Durbin.