Impact des véhicules lourds sur la sécurité aux passages à niveau – Développement d'un outil de conception adapté (TP 14172F)

Summary

As part of a study commissioned by Transport Quebec aimed at evaluating the impact of commercial vehicles on the safety of railway crossings, various heavy vehicles were tested (buses, straight trucks and tractor-trailer combinations) in order to determine their acceleration and braking performance. The goal of these tests was to identify typical braking and acceleration performances of various classes of commercial vehicles used in the calculation of sight triangles at railway crossings. Results were used to develop a railway crossing design and verification tool to be integrated in the new RTD 10 standard.

A total of 21 commercial vehicles were tested during the period of 3 August 2002 to 11 February 2003. Testing was performed in Quebec on the test tracks of the Centre de formation en transport routier (CFTR) in Saint-Janvier, on the test tracks of PMG Technologies in Blainville, on eight railway crossings located in the area between Blainville and St-Jérôme, and on a railway crossing located in a logging area north of La Tuque. Brake tests were conducted on a wet asphalt surface while acceleration tests were conducted on a dry asphalt surface and on dry railway crossing sites. Acceleration tests from the stop line to the crossing’s safe clearance line were also performed at each of the nine typical railway crossings.

The results of these tests were used in the development of a mathematical model of heavy vehicle acceleration according to the vehicles’ technical specifications. The model helped to identify various classes of commercial vehicles to be used and to determine the worst acceleration performances associated with each class of vehicle. Brake testing results helped to identify typical braking performances of these heavy vehicles. The acceleration and braking performances were then combined with various criteria associated with driver perception and reaction times as well as driver performance and skill during gear shifting and braking. Safety margins were also added to driver performances and vehicle approach speeds in order to better reflect real situations.

Taken together, these typical performance parameters were used to calculate minimum sightline distances or sight triangles according to the class of commercial vehicle as well as the roadway profile of the approach and exit of the crossing. The crossing times are presented on reference graphs and the stopping sight distances in the form of tables. These graphs and tables present typical roadway profiles with 2% and 5% grades. For all other roadway profiles, a simple extrapolation can be performed. This procedure can be adapted to commercial vehicles of all configurations, weights and dimensions, and operational characteristics, as well as all road conditions and all train and vehicle speeds, under normal weather conditions. This tool thus permits the calculation of sight triangles and can be integrated into the draft RTD 10 regulation issued by Transport Canada’s Rail Safety Directorate on 24 July 2001 titled Grade Crossing Regulations – Maintenance, Inspection and Testing.

The final tool consists of stopping sight distance (SSD) tables and crossing time reference graphs. The tables present the SSD according to the type of braking system (i.e., ABS), the roadway profile, and the posted speed limit. The graphs present the crossing times according to the class of vehicle, the roadway profile, the safe clearance distance over the crossing, and the possibility of changing gears. Methods of using the graphs for tanker trucks, grade crossings near an intersection, and grade crossing surfaces in poor condition are also offered.

Finally, some recommendations are made concerning the integration of the tool into RTD 10, the use of standard units of measure and fixed crossing reference times in RTD 10, and the repeal of government legislation prohibiting the changing of gears when going over railway tracks.

Project description

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This report reflects the view of the authors and not necessarily those of the Transportation Development Centre.