SOUND Transit has awarded a $US 24m contract to Advanced Rail Management (ARM) to perform rail grinding, polishing, and engineering inspection services on the 66km Link light rail network centred on Seattle.
The five-year contract includes five options for one-year extensions and applies to the existing network as well as new extensions, including the I-90 floating bridge across Lake Washington.
Work will involve corrugation measurement and track geometry, ultrasonic, and eddy current testing as part of the inspection and quality assurance requirements, and is described as one of the most comprehensive rail assessment and maintenance contracts awarded by a North American transit agency.
For example, the contract is the first of its kind in North America to require rail polishing that adheres to customised acoustic requirements, which are based on ISO 3095, which is considerably more demanding than the EN 13231-3 standard typically deployed in North America.
To achieve Sound Transit’s goals, ARM, along with the National Research Council of Canada, an ARM consultant on the project, will implement a gradual-preventive grinding programme. ARM will utilise a variety of hi-rail and railbound grinding equipment fitted with coarse to extra-fine-grit grinding stones depending on the metal-removal and surface-finishing requirements. Milling equipment will also be available if needed.
To prepare for the grinding and polishing programme, ARM and its consultants will conduct a comprehensive inspection programme that will quantify rail surface conditions. Measurements will include:
- systemwide track geometry testing of all typical parameters, such as curvature, gauge, profile and alignment. It will also include optical rail profile measurement
- ultrasonic testing (UT), which will identify internal rail defects, including detail fractures from shelling, broken or fractured rail base, defective plant or field welds, and bolt-hole cracks by type, size, and location. Squats and surface cracks that are identified by the UT test vehicle will be verified by hand tests
- pre- and post-grind eddy current testing, which will measure surface crack length, depth, and geometry; proximity to other cracks; and electromagnetic properties of the rail base material. Reports will include measurements, graphs, images, and trending reports; defects will be colour-coded to distinguish the severity, and
- corrugation measurement collected by a Corrugation Analysis Trolley (CAT), including roughness measurements that reference the guidelines of ISO 3095.
ARM will use data from these measurements to prioritise locations, estimate metal removal and the number of passes that will be required, and determine the total number of kilometres to be addressed in order to establish an effective gradual-preventive grinding program. Corrugation measurement data will be used to guide rail polishing efforts to meet Sound Transit’s five-micrometre surface roughness target within the wheel-rail running band.
“Sound Transit’s grinding and polishing acceptance criteria will ensure that the wavelength signature of the finished rail will mitigate the types of noise and vibration-related problems previously encountered on the system,” says Mr Mark Reimer, ARM’s director of business development and projects.