South of Rockhampton in Queensland, Australia, are a number of drawbridge-like crossings that carry 2-feet tracks of the Sugar Cane Railway operated by private sugar mills over the electrified North Coast Line of the Queensland Railway. When locomotives of the Sugar Cane Railway, also known as Tramways, need to cross the mainline, the drawbridges are lowered, and after the trains have passed, the two leaves of the bridges are raised up again. Queensland is (possibly) the only place in the world where drawbridges carrying railway tracks over another pair of railway tracks are found.
From the engineering point of view, drawbridges for tracks-over-tracks crossings are not necessary because such crossovers are easily handled by junctions, sometimes also called diamond crossing in reference to the diamond-shaped center. The two tracks need not necessarily be of the same gauge.
In Queensland, however, the North Coast Line is crossed by the Sugar Cane Railway in no less than 15 locations. Three of these crossings have either an underpass or overpass, but in the remaining 12 crossings drawbridges are used. If regular diamond crossings were implemented in each of these 12 locations, the high-speed “Tilt Trains” operating the North Coast Line would have never ran at its desired speeds, since diamond crossings impose speed restrictions.
So, in order to allow the Electric Tilt Trains, which are one of the fastest trains in Australia having a top speed of 160 km/h, to run at high speed, drawbridges were built instead of level crossings.
The drawbridge is always in the upright position allowing Queensland Railway trains to pass. As a cane train approaches the drawbridge, the driver activates the drawbridge by a remote control in the locomotive cabin. This changes the Queensland Railway signals to stop and starts lowering the drawbridge. Once the drawbridge is in place, the cane train can cross the Queensland Railway line. Once the cane train has passed, the drawbridge automatically lifts to clear the mainline track and returns the line signals to proceed. If a Queensland Railway train is approaching the drawbridge, the drawbridge will not lower even if attempted to by the cane train driver. If the cane train does not stop at the red signal, a “catch point” will derail the cane train to prevent it from crossing the path of the high speed train.
Interesting post. I've always been a proponent of KISS engineering and the "if it works, then it works" style design. Over 40 years in the chemical industry so far. That looks exactly like the type of solution I would have championed.
ReplyDeleteFor where its at and how much its used, I don't think there could be a better solution. And you're absolutely correct, it's 100% KISS.
Delete