President Post – Impact of Heat on Train Operations

August 14, 2012

The August heat in Texas is tough on man and machine.  While DCTA’s new rail cars are handling the heat well, there have been some occasions where the heat has slightly impacted our operations.  This has been related to the temperature of the rails, and has caused some limitations on our maximum speed.

The A-train (like most passenger rail lines) operates on continuously welded rail.  This greatly improves ride quality and reduces maintenance requirements.  Depending on the temperature at the time the welds are made, the rail is stretched or compressed to maintain an optimum tension.  If it is stretched too much, the contraction during cold weather can break the welds.  If it is not stretched enough, extremely high temperatures can create kinks or buckling in the tracks which pose a risk to train operations at higher speeds.  During a normal range of temperatures, the normal tension level is well within limits, and there is no impact.

In cases where the track temperature does get too high, train speeds must be reduced.  When the track temperature reaches 150 degrees, we must lower our maximum speed from 60mph to 40 mph.  This usually only has a marginal impact, and our crews can often make up the time.  Our partners at the Trinity Railway Express are more often impacted than us.  This is due to their higher maximum speed (79 mph) versus the A-train maximum speed (60mph), and a lower temperature threshold for speed reduction of 140 degrees to lower speeds from 79 mph to 60 mph.

These practices are for the safety of our passengers and to protect our infrastructure.  Stay cool, Fall is on the way!

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