TOO HOT TO HIGHBALL? Live from the Third Rail notes that some Washington, D.C. area suburban trains running on the old Baltimore and Ohio run slower on hot days account CSX Transportation rules slowing trains to reduce the risk of derailment on sun kinks.

Are there temperature-related speed restrictions in the Chicago area? I believe so, but they're less stringent than CSX's on the major carriers, Union Pacific, Canadian Pacific, and Burlington Northern Santa Fe, and much of the track is Metra's, which gives them some discretion to limit the use of tracks by freight trains that might subject the track to additional stresses. We've also learned a few things about sun kinks and anchoring rails, starting with a rather scary North Shore derailment at Racine in the 1920s.