On January 4, 1987, two trains collided on Amtrak's Northeast Corridor main line near Chase, Maryland, United States, at Gunpow Interlocking.

Amtrak train 94, the Colonial, (now part of the Northeast Regional) traveling north from Washington, D.C., to Boston, crashed at over 100 miles per hour (160 km/h) into a set of Conrail locomotives running light (without freight cars) which had fouled the mainline.

[1] The Conrail locomotive crew failed to stop at the signals before Gunpow Interlocking, and it was determined that the accident would have been avoided had they done so.

In the aftermath, drug and alcohol procedures for train crews were overhauled by the Federal Railroad Administration (FRA), which is charged with rail safety.

In 1991, prompted in large part by this crash, the United States Congress took even broader action and authorized mandatory random drug-testing for all employees in "safety-sensitive" jobs in all industries regulated by the U.S. Department of Transportation (DOT) including trucking, bus carriers and rail systems.

The train had 12 cars and was filled with travelers returning from the holiday season to their homes and schools for the second semester of the year.

It was later discovered that someone had disabled the cab signal alerter whistle on lead unit #5044 with duct tape, muting it almost completely.

Unlike some interlocking arrangements, Gunpow had no provisions for derailing and stopping a car or locomotive that is about to foul a turnout that is aligned against it.

[1] NTSB investigators determined that immediately prior to the collision, the interlocking had been properly configured for through movement on track #2.

Event recording devices on the Conrail locomotives indicated that the consist was moving at approximately 60 miles per hour (97 km/h) when an emergency brake application was made by engineer Gates.

The brake application occurred after passing the distant signal, which as previously noted, was indicating APPROACH, requiring an immediate speed reduction.

Examination of the interlocking system's computerized event recorder revealed that the Conrail consist forced its way through the turnout and onto track #2 approximately 15 seconds before the collision.

With his train approaching Gunpow at more than 120 mph (190 km/h),[1] engineer Evans had little time to react to the sudden signal change and the presence of the Conrail locomotives in his path.

[1] Amtrak’s lead locomotive, AEM-7 #903, ended up among some trees on the west side of the right-of-way, with the forward cab crushed.

NTSB investigators later concluded the Amtrak train’s speed wasn’t a significant factor in the events leading to the wreck.

Witnesses and neighbors ran to the smoking train and helped remove injured and dazed passengers, even before the first emergency vehicles could arrive at the location.

Emergency personnel worked for many hours in the frigid cold to extricate trapped passengers from the wreckage, impeded by the stainless-steel Amfleet cars' skin resistance to ordinary hydraulic rescue tools.

[1] It was several days before the wrecked equipment was removed and the track and electrical propulsion system were returned to service.

A National Transportation Safety Board (NTSB) investigation revealed that had Gates slowed down at the signals as required, he would have stopped in time.

[4] Gates and Cromwell were immediately suspended by Conrail pending an internal investigation, but resigned rather than face certain termination.

The two dissenters to the report believed that it was unreasonable to assign contributory blame to the Amtrak engineer based solely on the premise of the Heritage car lowering its speed limit.

In a 1993 interview with The Baltimore Sun, Gates said the accident would have never happened if not for the cannabis, saying that it had thrown off his "perception of speed and distance and time."

Since then, railroads are required by law to certify that their engineers are properly trained and qualified, and that they have no drug or alcohol impairment motor vehicle convictions for the five-year period prior to certification.

An employee may be required to take a breath test and/or provide a urine sample if the Company reasonably suspects violation of this rule.

In 1991—prompted in large part by the Chase crash—Congress authorized mandatory random drug-testing for all employees in "safety-sensitive" jobs in industries regulated by DOT.

On January 4, 2007, the 20th anniversary of the crash, her family visited the theatre for the first time and attended a ceremony at the McDonogh School held in honor of their daughter.

[6] The Baltimore County Fire Department's medical commander at the scene 20 years earlier told the newspaper that the Amtrak crash is still being used as a case study in effective disaster response.