The casscade tunnel in Washington state is the longest railroad tunnel in the united stateit is about 14 the lenght of the seikanabout how long is the cascade tunnel?

It may be l4 miles. the Trans-Hudson ( Goddard) tunnel of the former PRR which will be l00 next year, is probably the longest subaqueous tunnel of it s type - and is rated for 80 MPH operation of heavy duty locomotives, not subway cars. The Goddard is l5,600 feet long or about 2.95 miles and some change- try it on a calculator. it has never been as much in the public eye as the automotive vehicular tunnels, the Holland and Lincoln.The Cascade tunnel ( which has an automatic ventilating system installed in the past 30-odd years with remotely controlled tunnel doors ( also keeping out vandals) and ventilation pumps turned on by approaching pressure waves of locomotives is a massive engineering feat, but is an intermountain ( name defines itself) tunnel and not a subaqueous ( Under water) type, the latter much more challenging to the engineer.