Engineers are converting the 2.6 mi (4.2 km) Anton Anderson Railroad Tunnel that connects the isolated town of Whittier, Alaska, to the rest of the state into a combination highway-railroad facility that supports motor vehicles as well. By June 2000, vehicles will be able to drive through the tunnel, making it the longest rail-highway tunnel in North America and the longest highway tunnel in the United States. This $57-million tunnel is the first one in the United States to use a combination of portal and jet ventilation fans and to be accessible to the public, thanks to a unique computerized traffic control system. One of the most complicated aspects of the project was the design of the tunnel control system (TCS) and its interaction with the proposed train signal system (TSS). The TCS monitors and controls all of the tunnel systems, including vehicle detection, surveillance, illumination, ventilation, driver information, highway signals, and gates. The TSS, which is responsible for train movement through the tunnel, monitors and controls opposing train movements, switches, track conditions, and signals. When placed in highway mode, the TCS signals to the TSS that the tunnel is in this mode and locks out the TSS--denying rail movement--until all vehicles have cleared the tunnel, the gates are closed, and the operator confirms the tunnel is clear. When a train approaches, the TCS will be prompted to clear all vehicles from the tunnel and surrender control to the TSS.


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  • Accession Number: 00790694
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 17 2000 12:00AM