The Maryland Transit Administration reports that CSX has issued heat orders for Monday from 1 to 7 p.m. This will affect trains on the Brunswick and Camden lines, which will operate 20 miles per hour under their normal maximum speed. Officials said trains won't travel at less than 40 mph, but delays can range from 10 to 15 minutes. CSX operates the Maryland Area Regional Commuter Brunswick and Camden lines for the MTA on CSX-owned tracks.

According to the MTA, heat restrictions are issued for the two lines when temperatures are forecast to reach near 90 degrees or in the event that temperatures experience a 25-degree change. Track components can expand, contract or shift under those conditions. CSX also sends inspectors out to check the tracks during those conditions, which can cause delays as trains headed in opposite directions use one track through those areas. The restrictions don’t apply to the Penn Line, which has a higher temperature threshold for heat orders.

Amtrak operates MARC's Penn Line, which connects Washington and northeastern Maryland through Baltimore; CSX operates the Camden Line, which runs between Washington and Baltimore, and the Brunswick Line, which provides service between Washington and points north and west, including Frederick and Martinsburg, W.Va.