Broad guage -- or any non-standard gauge limits what you can buy on the open market. Lots of equipment has to be custom-built or at least specially ordered.

Third rail is not really a problem. Most heavy rail transit systems use third rail. It simplifies clearance issues in tunnels.

But, let's say you need a ballast tamper or ballast regulator. You cannot buy a standard model or contact a contractor to just haul one in. Even hi-rail equipment to be mounted on road vehicles has to be custom built -- and the road vehicle tire spacing (the tires ride on the rails for propulsion, the flanged wheels are only for guidance) has to be adjusted.

You may never see maintenance equipment while the system is in operation, but it is still needed.

If I recall, BART uses concrete ties. These had to be custom made to the wider gauge. If there are any wood ties in use, they have to be custom cut to a longer length and have the pre-drilled spike holes located at a different spacing.


Being able to connect to the national rail system has some small but important advantages. Let's say you need to bring in ballast. You can find side or bottom dump cars that would otherwise still fit within a transit system's clearances.

Transit systems receive a variety of heavy equipment and may need to send out equipment for maintenance that cannot be performed locally.

Let me give just one example: The Denver light rail system (RTD) has a connecting track with UP. It's located near the downtown RTD shops. Normally this track is blocked by derails on both side and a locked gate.

But the RTD Unimog not only has transit couplers to be able to move a disabled (or stranded in a section without electric power) light rail train. It also has a knuckle coupler for moving standerd freight cars.

Not only can RTD receive new light rail vehicles by rail (loaded on special flat cars) and then winch them off those car via a ramp in the shop area, but let's say it needs anything from a replacement truck for a light rail vehicle to new rail sections.

Anything heavy on a flat car can be pulled into the shop building, where the heavy-duty overhead crane can lift it off.


No, a non-standard gauge is not a huge impediment. But it does impose a number of inconveniences.

-- Ernest