Preventing rail kinks

Rail kinks can occur on the prototype as well as on our model railroads. As materials are heated or cooled they expand or contract at different rates. Back in January, after a period of cold and dry weather, the Tri-State Model Railroad club noticed a couple of areas where the rails had kinked. In the photo you can see the left hand rail of the turnout has been displaced and is up against the point rails of the turnout, even though the turnout is lined for the straight route. These types of rail kinks can occur when the wooden bench work or layout base layer shrinks in periods of cold weather and low humidity. By keeping the temperature and humidity in the train layout room at a consistent level, it will help reduce the expansion and contraction of the wood, but may not totally eliminate the problem. The question is, how can you prevent these types of rail kinks from happening?

The easiest solution is to leave slight gaps, about the thickness of a business card, between each section of track at the rail joiners as you lay the track during construction. The gaps will allow the rails to move slightly and prevent them from breaking off the little plastic spikes that hold the rails in gauge when the bench work expands or contracts and places stress on the rails. Many modelers advise against soldering all rail joiners just for this reason. If the joiners are soldered, then the rail can't move and the only place for the stress to go is to the weakest point, which usually is on a curve or at a turnout. These expansion rail gaps are not to be confused with electrical isolation gaps which are used between different power districts. Electrical isolation gaps should have a piece of styrene inserted to prevent them from closing up and possibly causing a short.

Once the rail kink occurs, the only solution is to cut gaps to relieve the stress and then glue the rail back to the ties, or replace the turnout or track section. In the situation that occurred at the club, the only solution was to replace the turnout as repairing it was not feasible. I used a Dremel tool with a cut off wheel to cut through the all rail joiners on the rails that were soldered to the turnout. I was amazed how much stress was on the rails as I completed the cuts. After soaking the ballast with alcohol, I removed the old turnout and cleaned the cork roadbed base. I installed a new turnout after trimming the main line track rails to fit, as the turnout was from another manufacturer and longer than the old one. I left slight gaps at the rail joiners to prevent rail kinking again at this location in the future.