Field investigations into the performance of magnetic track brakes of an electrical multiple unit against slippery tracks. Part 1: Adhesion improvement

Some rolling stock designed for conventional and high-speed railway operation has magnetic track brakes (MTBs) to have an additional brake independent of the wheel-rail adhesion to be mostly activated in emergency situations. In recent years, interest has grown in some railways towards the possible use of MTB against slippery tracks. However, there seems to be a lack of knowledge on the major benefits and possible side effects of using MTB to overcome low-adhesion conditions. This hinders the realization of a cost-benefit analysis to look at possible implementation. In order to contribute to a better understanding, field tests have been performed with the permanent MTB of an electrical multiple unit in a stabling yard. Low-adhesion conditions have been created by three types of contamination representative of slippery tracks, i.e. leaves, water, and grease. The entire work has been divided in two parts. In this Part I, emphasis is put on the adhesion recovery, in particular the benefit for subsequent wheel (or train) passages. Baseline tests (i.e. no use of MTB) have also been performed with water and leaves. Additionally, an adhesion improver widely used in the Dutch and British railways has also been tested with leaves to allow for a comparison in effectiveness with MTB under similar operating conditions. In each test, the wheel-rail adhesion conditions along the initially contaminated track have been measured to evaluate the adhesion improvement under the different testing conditions.