What is a track clearnace car used for?

[Red Horse]

I've been on ebay and have seen auctions for HO train track clearance cars...what are these and do I need one?

Are they used to make sure my tunnels are not too short/low?

[ndbprr]

No you don't need one but the real railroads did.  On a model railroad they are a novelty car and until you run out of otherbthings to buy I would stay away from them.  Often a railroad would use them to make sure clearances remained what the rules called for.

[jeffrey-wimberly]

A track clearance car is used to check the clearance around and above the track. You can do the same with an NMRA Standards Gauge.

Here's a Wikipedia entry about a track clearance car.

 

 

[Texas Zepher]

Are they used to make sure my tunnels are not too short/low?

And wide enough.

[dehusman]

Tunnels,  bridges, rock cuts, buildings, signals, water towers, mail cranes, etc.  Any fixed object along the railroad.

Modern railroads do it with a hirail equipped with laser range finders.  It becomes critical when moving hi-wide loads or large cars (auto racks, double stacks, long/big engines).

Dave H.