Deadly D.C. Metro collision

Federal and local investigators examine the wreckage of a train which collided with another train in Washington, June 23, 2009. At least seven people were killed on Monday in the collision, the deadliest in the 33-year history of Washington's Metro Area Transit Authority. REUTERS/Larry Downing (UNITED STATES DISASTER)

Investigators and officials look over the collision scene of two Metro transit trains in Northeast Washington, Tuesday, June 23, 2009. (AP Photo/Gerald Herbert)

Tijuana Cox, of Prince George's County, MD., who was injured in yesterdays collision of two Metro transit trains in Northeast Washington, stands near the scene in the early morning Tuesday, June 23, 2009. (AP Photo/Gerald Herbert)

WASHINGTON - JUNE 22: Rescue workers respond to the site of two Red Line Metrorail trains that collided with one another between the Fort Totten and Takoma Park stations during the evening rush hour June 22, 2009 in Washington, DC. Early reports indicated at least four people died and dozens of injuries were sustained in the accident. (Photo by Win McNamee/Getty Images)

District of Columbia Fire and Emergency workers at the site of a rush-hour collision between two Metro transit trains in northeast Washington, D.C. Monday, June 22, 2009. (AP Photo/Pablo Martinez Monsivais)

WASHINGTON - JUNE 22: Rescue crews work on the wreckage of two Red Line Metrorail trains that collided with one another between the Fort Totten and Takoma Park stations during the evening rush hour June 22, 2009 in Washington, DC. Reports indicate that at least six people are dead and dozens of injuries were sustained in the accident. (Photo by Robert Giroux/Getty Images)

WASHINGTON - JUNE 22: An injured man is brought away by rescue crews from the wreckage of two Red Line Metrorail trains that collided with one another between the Fort Totten and Takoma Park stations during the evening rush hour June 22, 2009 in Washington, DC. Early reports indicated at least four people died and dozens of injuries were sustained in the accident. (Photo by Alex Wong/Getty Images)

WASHINGTON - JUNE 22: Rescue crews climb in to the wreckage of two Red Line Metrorail trains that collided with one another between the Fort Totten and Takoma Park stations during the evening rush hour June 22, 2009 in Washington, DC. Early reports indicated at least four people died and dozens of injuries were sustained in the accident. (Photo by Alex Wong/Getty Images)

WASHINGTON - JUNE 22: A body is brought out by rescue crews from the wreckage of two Red Line Metrorail trains that collided with one another between the Fort Totten and Takoma Park stations during the evening rush hour June 22, 2009 in Washington, DC. Early reports indicated at least four people died and dozens of injuries were sustained in the accident. (Photo by Alex Wong/Getty Images)

District of Columbia Fire and Emergency workers at the site of a rush-hour collision between two Metro transit trains in northeast Washington, D.C. Monday, June 22, 2009. (AP Photo/Pablo Martinez Monsivais)