The National Transportation Safety Board (NTSB) issued three safety recommendations Thursday, calling upon industry to install crash-resistant, inward- and outward-facing cameras in all rail transit vehicles.

The recommendations, issued to the Federal Transit Administration and the Southeastern Pennsylvania Transportation Authority (SEPTA), call for recorders with a minimum of 12-hour continuous-recording capability that can verify crew actions and train operating conditions. The NTSB says the recorders must be easily accessible to review, with appropriate limitations on public release, for accident investigation and as a tool to improve operational safety.

“In 47 of the 64 rail transit accidents the NTSB investigated between 1976 and 2015, audio and image recorders would have greatly helped in learning what happened by documenting and preserving data describing the actions and conditions leading to an accident,” said NTSB Chairman Robert L. Sumwalt.

The NTSB is currently investigating a Feb. 21, 2017, accident in Upper Darby, Pa., where a SEPTA train collided with the rear of a second SEPTA train stopped on a loop track near the 69th Street station. In a post-accident interview, the operator of the striking train said he could not remember his actions immediately prior to the collision. The train was not equipped with forward-facing cameras nor audio or image recorders in the operating cab.

The NTSB has long advocated the broader use of recorders as a means to improve transportation safety; the issue is currently on the agency’s Most Wanted List of transportation safety improvements.