WITH AMTRAK’s Northeast Corridor electrification between New Haven and Boston due to come into service later this year, teams from Balfour Beatty Construction Inc and its joint venture partner Mass Electric Construction Co are currently finishing the installation of the 25 kV catenary. They faced a major challenge in wiring two lifting and three swing bridges in Connecticut, which carry the line across rivers and estuaries busy with boats and yachts. With the bridges opening and closing several times each day, special arrangements were needed to energise the moving sections.

BBCI has opted for fixed contact wires supplied by Furrer + Frey of Switzerland. The copper/silver wires are held in a longitudinal aluminium tube which can be rigidly secured to the bridge structure. At each end of the bridge is a portal frame carrying the transition between normal and fixed catenary, linked by undersea cables.

On the swing bridges, short sections of contact wire are hinged vertically, and rotate clear before the bridge is opened. The rolling lift bridges call for a more complex solution, as the catenary must be moved clear of the space where the bridge counterweights descend. To span the gap, the wires are carried on a mobile frame developed from a rail-mounted portal crane (below). The rigid catenary is mounted on hinged insulators, so that it can swing sideways to clear the adjacent section of wire when the frame is retracted. Guide clamps force the swinging section into the correct alignment automatically as the frame rolls to and fro.

Because of severe winters, where freezing rain can deposit ice layers up to 30mm thick, the mechanism was tested in the Swiss National Laboratory for Climate Control prior to installation.

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Balfour Beatty Construction Inc 140 Furrer + Frey 141

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