Why are Tokyo subways so quiet, even though they have metal wheels?

An observation by Frank X. Didik ---February, 2014
Updated January 18, 2024


The reason is simple. In Tokyo, the tracks are completely smooth and the expansion joints merge slowly together, with two angular cuts. Many trains around the world use this same system. Further, the expansion joint can move further, thus potentially the tracks need to be serviced less frequently. On the other hand, here in NYC, we use the earliest methods by leaving a space between the rails, so in the summer time, when the the rail expands, a space is still present. Every wheel that rolls over the expansion joint makes a noise and vibration. Besides being noisy, this vibration ultimately wears the train (and rider) out quicker.

Tokyo subway expansion joint illustrating the interlacing expansion joints that provide for a perfectly smooth transition, from rail to rail.

Tokyo expansion joint illustrating the holding plate surrounding the expansion joint. Though the gauge of Tokyo subway tracks is smaller, this does not have an effect on noise and vibration. For the record, I prefer the wider gauge of NYC subways, since it provides potentially greater stability in softer ground environments.

Typical expansion joint as found on the NYC subway system. A space, measuring over 1/2" is left so that the rails can expand in the heat. This leaves a constant bump with is both noisy and wears the train and joint out quicker. I propose that over time, the rails can either be replaced or retrofitted. This would not effectively increase the cost of maintenance. I will explain this further, when we meet.

If you are a government official or a major contractor, please contact Frank Didik at inquiry [at] didik.com for a full report on how subways can be silenced and by doing so, reduce the damage to the subway car and tracks, caused by vibration, make the ride more comfortable and enjoyable, thus increasing ridership and ultimately save money, when vibration repairs are taken into consideration.

Frank X. Didik

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