Locomotive Exhaust Temperatures During High Altitude Tunnel Operation in Donner Pass

Locomotives in heavy-haul service at high altitude and within unventilated tunnels operate under some of the most extreme conditions encountered in the U.S. with regard to high ambient temperatures and high locomotive exhaust temperatures. Consideration of such conditions is crucial to the design of future catalytic emission control systems for locomotives. Field testing was conducted on two locomotives certified to U.S. Federal Tier 2 locomotive emissions standards operating as part of a four-locomotive consist pulling a heavy-freight train west-bound through the Donner Pass Region in late August 2007. The highest post-turbine exhaust temperatures observed over the entire test route occurred within Union Pacific Tunnel 41 — an approximately two-mile-long, unventilated tunnel located near Norden, California. Engine protection measures within the electronic locomotive and engine management systems of both locomotives limited the peak exhaust temperatures encountered during the tests to less than 560°C.