 One accident at the Mousetrap , a complex interchange , had national ramifications . On August 1 , 1984 , a truck carrying six torpedoes for the U.S. Navy overturned . The situation was made worse as no one answered at the phone number provided with the cargo , and an unknown liquid was leaking from one of the torpedoes . It took more than three hours before any military personnel arrived on the scene , U.S. Army personnel from a nearby base . The incident left thousands of cars stranded and Denver 's transportation network paralyzed for about eight hours . Approximately 50 residents in the area were evacuated . Investigations later revealed that the truck driver did not follow a recommended route provided by officers , and was specifically warned to avoid the Mousetrap . The Navy promised reforms after being criticized for providing an unstaffed phone number with a hazardous cargo shipment , a violation of federal law , and failing to notify Denver officials about the shipment . The Mousetrap was grandfathered into the Interstate Highway system , with some structures built in 1951 . The incident provided momentum to rebuild the interchange with a more modern and safer design . Construction began in several phases in 1987 and the last bridge was dedicated in 2003 . 
