WASHINGTON ( CNN ) -- Transportation investigators Wednesday discovered `` anomalies '' in an essential control circuit of a track where a fatal crash between two Washington subway trains killed nine people . Investigators work Tuesday at the site of the Metro train crash in Washington . Each section of the transit system 's track contains a circuit that transmits and receives signals that generate speed commands for trains , said Debbie Hersman of the National Transportation Safety Board . She said the circuits are `` vital providing information to the operators and the train itself when on automatic . '' Investigators found no problems in five of the six circuits on the stretch of track in the crash area . But they found `` anomalies '' with the sixth circuit , Hersman said . She would not say what those anomalies were but said simulated crash tests would be conducted to try and determine what caused the deadly accident . The findings could mean that the striking train , which was on automatic , did not know to slow down because another train was stopped on the track ahead . Hersman said investigators walked the tracks Wednesday , finding markings on the track that indicated emergency braking had taken place . Investigators hoped Thursday to interview the operator of the struck train , who was released from a hospital Wednesday . The driver of the striking train was killed . The crash , the worst in the history of Washington 's transit system , known as the Metro , occurred along the congested Red Line just before 5 p.m. Monday on an above-ground track section near Takoma Park , Maryland . Both cars were on the same track , traveling in the same direction -- southward from Fort Totten Metrorail station to the Shady Grove station . The struck train had stopped behind another train undergoing service and was awaiting directions to move ahead . The striking train was pulling some of the oldest cars in the fleet of the Washington Metropolitan Area Transit Authority . On Wednesday , House Majority Leader Steny Hoyer said he plans to seek $ 3 billion for Metro transit capital improvements , some of which would likely be spent to replace some those old Series 1000 cars , purchased between 1974 and 1978 . Upon impact , the train pulling those Series 1000 cars jumped on top of the other train . All the fatalities were on the striking train , Train 112 , Metro transit spokeswoman Angela Gates told CNN on Wednesday . In the collision , the front car of the striking train was severely damaged , leaving minimal space for survivability , said Hersman . According to one report , 50 feet of the 75-foot length of that lead car were lost to the accident , leaving only one-third of the space after the crushing impact . Watch Hersman talk about previous warnings » . The NTSB recommended in 2006 that Metro transit replace or retrofit all of its Series 1000 trains , to bring them up to current safety standards . Metro transit responded that because it was constrained by tax-advantage leases , it intended to keep the 1000 Series until the end of 2014 . `` Our recommendation was not addressed , so it [ the case ] has been closed in an unacceptable status , '' Hersman said . The NTSB has no regulatory powers and ca n't force implementation . Watch Hersman talk about the computer systems » . `` The safety of our citizens is our highest priority and we must take every precaution that this loss of life does not occur again , '' said Hoyer , a Democratic congressman from Maryland . He said he would soon introduce a final measure to authorize dedicated federal and local funding for Metro . The Series 1000 cars comprise a quarter of Metro transit 's 1,126 cars , or nearly 300 cars , Gates said . At $ 3 million per car , the agency ca n't afford to replace them all at once , Gates said . Each car has a 40-year life and can last until fiscal year 2015 , she added . `` So we 've taken steps to keep them in good condition . '' She said they have been phasing out the outdated cars as new cars are bought , she said . That plan has n't gone as quickly as anticipated , however , because of an increase in ridership , Gates added . The lead train in Monday 's crash contained newer 5000-Series and 3000-Series cars . These have data recorders , which will aid the investigation a great deal if they are n't damaged , Hersman said . The recorders provide information on such things as speed , braking and emergency applications . She said there were no recorders on the rear train . The rear train was being operated in automatic mode , which is the normal operating procedure during rush hour . Washington transit trains are being operated manually until the cause of the crash is determined , Hersman said . She said there is no indication that any of the brakes on the rear train failed before it rear-ended the other train . `` Our investigators on scene yesterday did find some evidence of emergency brake application . They found the emergency mushroom , which is a button that was depressed in the control cab , and they also examined the wheels and the brakes , and they found that the rotors showed some bluing , '' Hersman said . `` That bluing is consistent with an emergency brake application , '' she said . Bluing indicates the rotors have been subjected to extremely high temperatures , and this can be caused by hard stops .
House majority leader to push for $ 3 billion in Metro transit funding . The transit authority wants to replace its aging Series 1000 cars . A train of Series 1000 cars rear-ended another train Monday , killing nine . Investigators question why computerized emergency system failed .