Arc flash shield on A Line bridge. Photo:courtesy of RTD.
The Denver area's Regional Transportation District (RTD) is preparing to do track and system work on the North Metro Rail Line.
Before work can be done on the track, RTD is installing various measures to protect the train and surrounding objects from the electricity used to power the train. Arc flash shields are being installed on the underside of existing bridges that pass over the North Metro alignment. These will protect the concrete structures from an arc of electricity generated between the train pantograph (framework mounted to the roof of the train car to collect power) and contact wire as the train passes underneath.
Arc flashing is generated by the electricity from the Overhead Catenary System (OCS wires) that run above the rail to power the rail cars. An occasional variance in track and rail height causes the car to lose contact with the wire. A flash of electricity occurs from the wire to the car in the shape of an arc. An aluminum shield is installed directly over the OCS wires to prevent damage to the bridges above from this occasional arc flashing.
Installation of the shield took place in July at Park Avenue and under Interstate 70.