A large swath of the US, including at least two dozen states, are under heat advisories or warnings to end the week as a heat wave pushes east. There are concerns extreme heat could risk straining rail networks. 

Earlier this month, Amtrak service between New York and Philadelphia encountered delays due to "heat-related" speed restrictions. Those restrictions could return as temperatures in the Northeast are expected to print near triple-digit territory through the weekend. 

Brutal temperatures could buckle tracks and result in passenger and freight rail delays, similar to what's happening in London as Network Rail told passengers earlier this week not to travel by train.