Tram braking distances under the influence of MgCl2 as a dust binding agent

A field study of friction loss during tram braking under the influence of MgCl2 has been carried out. The work was initiated after a collision in Trondheim, Norway, where a tram ran into a stagnant bus from behind. During the studded tyre season, an MgCl2 solution was regularly applied to the street surface as a dust binding agent, and was applied only hours before the incident. The objective of the project was to determine whether the use of this MgCl2 solution for dust attenuation may have contributed to a reduced top-of-rail friction at the moment of the accident. The study comprised of a literature survey, brake tests with trams and analyses to determine the friction conditions at four different top-of-rail conditions, i.e. dry, wet by water, wet by MgCl2 solution and dried/moist MgCl2, three braking modes, i.e. with friction controlled disk brakes, electromagnetic track brakes, and with one of four track brakes deactivated and three levels of target speed, i.e. 5 km/h, 15 km/h. and 30km/h. Around 110 individual tests were carried out. A main conclusion was that the use of MgCl2 resulted in significantly longer braking distances, especially for normal braking. Dried MgCl2 induced the longest braking distances, followed by wet MgCl2 applied to the track. The third longest braking distances went to the track wet by water, and the fourth, with the best friction, was for the dry track. One disabled magnetic track brake did not seem to have a major impact on the stopping length compared with all four magnetic track brakes activated. As a result of the investigation, Trondheim municipality has stopped the use of the MgCl2 solution as dust binding agent in streets where there is tram traffic.


  • English

Media Info

  • Pagination: pp 495-500
  • Monograph Title: Bearing capacity of roads, railways and airfields: proceedings of the ninth International Conference on the Bearing Capacity of Roads, Railways and Airfields: Trondheim, Norway 25-27 June 2013. Vol 1-2

Subject/Index Terms

Filing Info

  • Accession Number: 01596547
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • ISBN: 9788232102853
  • Files: ITRD, VTI
  • Created Date: Apr 21 2016 12:27PM