WASHINGTON – National Transportation Safety Board investigators on the site of Monday’s heavy-rail collision on Washington Metropolitan Area Transit Authority’s Red Line, found metal-to-metal compression streak marks on both rails of track for about 125 feet ending near the approximate point of impact, which is consistent with heavy braking. Earlier reports confirmed the mushroom button used to activate the emergency brakes had been depressed in the striking train’s cab, and brake rotors were discolored blue, which happens when high friction, such as heavy breaking, heats metal components.
Further, investigators Wednesday evening conducted tests at the accident site with a similar train and found that when the train was stopped in the same location as the stopped struck train, the train control system lost detection of the test train.
The Washington Metro system relies on about 3,000 track circuits to direct the trains when to proceed and when to stop. When running in automatic mode, as the striking train was Monday, the operator is primarily responsible to close the doors before leaving the station and override the system if need be.
Investigators will examine and test all circuits systemwide, as well as the rest of the train control system to understand how it functioned the day of the accident.
Investigators also interviewed the operator of the struck train who said he was running his train manually and felt a hard push from behind when struck.
The NTSB plans to conduct sight-distance tests, using trains similar to those involved in the crash. – Kathi Kube
