DOT-117 tank car

The DOT-117 (TC-117 in Canada) is a type of unpressurized tank car in use on North American railroads. The DOT-117 design was developed in the aftermath of the Lac-Mégantic rail disaster of 2013 in an effort to upgrade the specifications of the then-common DOT-111 and CPC-1232 designs.[1] It was announced on May 1, 2015 by the United States Federal Railroad Administration (FRA) and Canada's Transport Canada (TC).[1] The specifications require that the tank shells be constructed out of 9/16" steel, with 11-gauge sheet metal jackets, 1/2" thick head shields on the ends of the tanks, and improved valves over previous designs.[2]

Diagram showing construction of the DOT 117 tank car.

In order to implement the DOT-117 standard, the FRA and TC required that all new tank cars constructed after October 1, 2015 be built to the specification.[2] The agencies also imposed a retrofit schedule to bring in-service cars up to DOT-117 standards.[1] Depending on the volatility of the cargo carried, DOT-111 and CPC-1232 cars would be banned in certain services in a series of cut-off dates, with all such cars out of service or rebuilt by May 1, 2025.[1]