What is it called when there are two tracks running side by side and then they overlap ( 4 rails through bridge but only a bit wider than 2 rails.) as they go through a narrow bridge that is only wide enough for 1 set of tracks? They do not use the same track.
Gauntlet track?
Jim
That is called a gantlet. Most examples of gantlet track are scales, and the case you mentioned where two railroads use the same bridge.
Four rails, two frogs, and no points, that’s called a gantlet.
They are usually used where there is too little clearance for two tracks, such as in a tunnel. Also, as in the case of the New Haven’s Poughkeepsie bridge over the Hudson River, it served two purposes. Most important was that it prevented two trains from using the bridge at the same time, and it centered the load. Both designed to prevent damage to the bridge as trains got heavier in the modern era.
It seems to me that a scale track is really the opposite of a gantlet track. On a gantlet, there are two tracks that come together and “overlap” across the bridge. But at a scale, one track becomes two overlapping tracks before reverting to one.
Another way to look at it is that on the gantlet there are two frogs, one at each end where the overlap begins and ends, but there are no switch points. However, on the scale track there are two sets of points, but no frogs.
About ten years ago, several passengers were killed when two trains on the South Shore line near Chicago tried to share the same gantlet while traveling at speed in opposite directions. Needless to say, caution must be the order of the day when using a gantlet track.
Tom
I believe that Gauntlet bridge is gone now. Its to save money on bridge building, but in errors like this, its better to change it if you can.