Optimisation of a railway sanding system : adhesion tests

Contamination on the railhead such as crushed leaves, oxide formation or even changes in atmospheric conditions can cause adhesion loss between the wheel and the rail. In these situations, trains can lose some or all of their braking capacity leading to vehicles coming within dangerously close proximity to one another. Low adhesion situations are traditionally combatted by firing sand directly into the wheel/rail contact from on-board the train. Previous testing has been carried out to investigate the optimum sanding system set-up which delivers the most amount of sand to the wheel/rail interface. The testing presented in this paper is a continuation of the previous set-up tests and focuses on adhesion differences when sand enters the contact under low adhesion conditions. A full-scale test facility was used for these tests. Firstly, tests were undertaken which investigated the effect of sand density on the rail head and how this affects adhesion restoration. A second set of tests looked at how adhesion was restored when sand was fired into the contact using the ideal sanding system set-up found in previous testing.