Rail Expansion

[BaltACD]

To hold welded rail in place as the temperature rises several technologies are applied, begining when the rail is initially laid. The rail is heated or cooled to the temperature specified by the engineering department for the geographical terrirory where the rail is being laid. A higher temperature is specified for the South, where it is warmer longer, the for rail laid in the North.

The second technology that gets applied is a heavy use of rail anchors that are applied as specified to ties surrounding a rail joint..

The third technology that is applied is increasing the shoulder ballast distance from the end of the ties.

The 'normalized' rail temperature at the time of rail laying is designed to minimize the amount of expansion and contraction during the normal weather extremes of the territory. The rail anchors anchor the rail to the ties. The increased ballast shoulder distance provides more resistance against movement of the ties.

Having said all the above, welded rail creates many broken rails when there is a sharp temperature drop, and 'sun' kinks when the temperatures are high.

The reality is that Welded Rail is a technology that has yet to be FULLY MASTERED!

[AntonioFP45]

A few years back the Amtrak Auto Train derailed here in Florida on it's northbound run. I think at least one person was killed and numerous others injured. Temperature was very hot that day and while terrorism was thought off, the culprit was heat and the effect it had on the rail section which had been repaired recently.

[Modelcar]

....We expanded this topic on this forum last season for days on end....Dig back and I'm sure one can read pages and pages of this very subject here. I remember we even figured out by theory how much expansion would be in the 300 miles of tangent track stretching across Australia...and the answer was....Massive...!!! But the rail has been put down in a temp. bracket along with fastener design that allows it to be functional. But it sure is an interesting subject and we sure did discuss it right here.

[Trainman2001]

With all of this talk about cross-ties and rail joiners, I was thinking... (I knew I smelled smoke).

With ribbon rail being up to a mile long without a joint, how do they allow for expansion of the steel in hot weather. It seems to me that the change in length could be so great as to cause the rail to buckle. What do they do to control this?

BTW.. for the unititiated, rails are not soldered, but they are Thermite welded, Here they use metal powders containing aluminum and the steel alloys held above the open rail joint. The joint is surrounded with fire clay and the powder ignited generating a molten steel alloy they breaks though the bottom of the container above the rail and thoughly fills and welds the gap between the rails. I wouldn't recommend this method on a model RR.

Myles Marcovitch