One of the more annoying but common frustrations that model railroaders have to put up with is train derailments. It is common to have to troubleshoot layout issues during design and construction and the occasional derailment due to excessive speed or external causes such as wind, vibration or changes in car placement or order is to be expected; however, when a problem occurs at a specific place on a regular basis it is likely that something is causing the problem.

If you have a problem you first should determine where the cause as well as the location is occurring and if the problem is only occurring with specific cars and locomotives. Just because the derailment occurs on a curve for instance doesn’t mean the curve itself is at fault – the wheels for instance may be jumping on a nail head causing instability that rocks the cars and then allows it to derail on he following curve. This may also indicate a problem with a specific wheel or car in a similar manner – so troubleshooting should test first with just a locomotive, then specific cars to see if specific causes and locations can be identified.

Besides just the wheels couplers also can cause problems – if they are not high enough to clear switch points or items and begin to swap or dip at specific points this can cause derailment. The fix is simple: adjusting the coupler by shims of plastic or a washer is usually enough to take out excess slack up and down movement.
The trucks also can be a problem, although this is very rare – when this occurs it is often that the screw holding the truck in place is too tight and needs to be backed out a bit.
Bumps or rises in your track caused by uneven surfaces or improperly secured rails can also be at fault. If the problem area is at a point where a table connects with another you may need to be certain they are level and securely connected together and not flexing as the system runs.

One of the most common areas to locate problems with the rails themselves are the switches – if you believe a switch is at fault first check that the frog and guide rails are clean and working smoothly as even a very small amount of dirt can cause problems. One tip on testing a switch is to run a spare truck across the switch with your fingers and see if you feel any instability. Using a NMRA track gauge and confirming the width and clearance for the switch points and adjusting if necessary is also a common fix that is necessary.