What is a guideway?
The O-Train Confederation Line’s ‘guideway’ is the footprint along which the Light Rail Vehicles (LRV) will travel. The guideway will span 12.5 kilometres across the City and feature a mix of at-grade, elevated and tunnel sections along which tracks will be laid and an Overhead Catenary System (OCS) will be installed. The guideway is being built mostly in the footprint of the existing Transitway.
Construction of the guideway began in 2014 at Hurdman Station. This summer, guideway work will continue in the east and will be ongoing throughout the alignment until 2017. Trackwork and OCS installation began in spring 2015.
What is trackwork?
The Confederation Line track has been designed to optimize many factors including safety, end to end travel time, passenger comfort, vehicle performance, and system maintainability.
Two types of track support will be used on the O-Train Confederation Line: ballasted tracks and direct fixation tracks. Each is selected to best suit the needs of the track’s environment along different portions of the guideway.
Types of track
Ballasted Track: Ballast, comprised of crushed stone, forms the trackbed where railway ties are laid. Railway ties consist of rectangular timber or precast concrete track supports that are laid perpendicular to the tracks.
Ballasted tracks will be installed on the guideway located outside of the tunnel, the LRT stations and Belfast Yard. This type of trackwork represents 2/3 of total guideway.
Direct Fixation Track: Direct fixation tracks, also known as ballastless track, use a rail fastener system that is directly anchored to a concrete trackbed instead of being placed on ballast.
Direct fixation tracks will be installed on the guideway inside the tunnel, the LRT stations and Belfast Yard. This type of trackwork represents 1/3 of total guideway.
Special Trackwork: Special trackwork (or crossovers) allow LRVs to transfer from one track to another or to cross intersecting tracks.
Special trackwork will help LRVs navigate at strategic locations along the alignment. This type of trackwork is found in the Belfast Yard and at over half a dozen other locations along the guideway.
How are tracks installed?
Confederation Line trackwork will be assembled by first joining rail lengths together using two welding techniques; thermite welding and flash butt welding. The welding method selected depends on the track’s location. The 24m long rails are first flash butt welded together in 150m long strings or sections and then the strings are pulled to their designated location where they are thermite welded together.
Thermite Welding: Thermite welding, also known as exothermic welding, is the process of pouring molten steel into a cast placed around a cross section of rail. The molten steel is created by an exothermic chemical reaction between aluminum and iron oxides. Thermite welding will be done in situ.
Flash Butt Welding: Flash butt welding is a forged weld created by placing an electrical charge between the cross sections of rails until the steel is malleable. The lengths of rail are then forged together using no filler material. Flash butt welding will generally be done before track work sections are moved on site.
How will the tracks be maintained?
The O-Train Confederation Line’s design approach has used a combination of architectural landscaping, track structure and periodic maintenance to minimize the build-up of snow, ice and vegetation and guideway.
Once in operation, regular maintenance will include visual inspections and removal of debris such as branches. Additional maintenance will be performed on an as needed basis.
In the winter, significant accumulation of snow on the rails will be removed with plows. In the event of heavy snowfall or ice, LRVs can be run along the alignment in the overnight hours to prevent build up.
How will the system be powered?
In addition to trackwork, guideway construction includes an Overhead Catenary System (OCS). The OCS is comprised of physical supporting structures, such as poles and wires. The OCS system distributes DC power from the Traction Power Sub Stations (TPSS) to the vehicle through a pantograph; a device mounted on the roof of an LRV that collects power through contact with the overhead wires. A total of nine TPSSs located along the alignment, integrated into stations and Belfast Yard structures, will convert electricity from the local power supply.