201803 – Moore – Track Circuit Activation Issues for DMUs

The first track circuits were developed in the 1870s. These were used on US Railroads. Over the following years they were used on railways around the world. There have been substantial developments in the engineering and technology used in track circuits through to the present time. However, after one hundred and forty five years we are still having problems with reliable operation of the track circuits in some applications.

This paper will examine the type of trains, track circuit configurations and infrastructure conditions that contribute to the performance limitations of the track circuit. The paper will cover engineering solutions and recent testing to address the reliable performance of the track circuits.

The issue is complicated and involves the signalling equipment, rollingstock and the track infrastructure. An understanding of these issues will assist the signal engineer in addressing solutions for reliable operation.