Harbor Drive Bridge

Harbor Drive Bridge

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History -

Harbor Drive is a major road South from downtown into National City. In the 1930's a bridge replacement project built the current structure over the AT&SF tracks as they leave the freight yard and head North past the Union Station Depot. Many upgrades occurred over time, including the installation of lights down the bridge median.

The Prototype -

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The bridge is approximately 1400 ft long. Construction is reinforced concrete with usually three round concrete bents at intervals as it rises to clear the tracks. At the point where it crosses the tracks, the bents become rectangular, and in places are cantilevered to provide support while clearance for trains is preserved. The side railings are also concrete to insure automotive crashes would not go over the edge onto the tracks below.

Pedestrian traffic is also permitted on the bridge. Sidewalks are an integral part of the structure.

Lights are installed down the median at fairly wide intervals. Early historical photographs of the bridge do not show lighting fixtures, so it is assumed they were added some time later. Nobody is sure when the lights were finally installed, or if the present lights replaced earlier fixtures.

Building the model -

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The model of the Harbor Drive Bridge was built by Charles McGill beginning in 2012. Detailed planning took several weeks including trips to photograph the prototype details and take measurements where possible.

Ed Carey also assisted by cutting materials and drilling holes for the bridge bents.

A construction mandate of this structure was that the center portion be removable. Directly under the bridge is a switch that might need maintenance, and trolley wire poles are also under the bridge in a couple of places. In fact, the trolley wire was broken many times during construction of the Harbor Drive Bridge model, and the contact wire was spliced with small brass washers as needed to maintain trolley and traction freight traffic. Upon completion of the bridge, the trolley wire was replaced with new wire for a distance of about 20 feet.

Built into the removable section are electrical contacts to provide power to the median light fixtures. The non-removable section lighting feeds wires down a tube next to the bents. On the prototype, these tubes are drainage pipes for storm water removal.

Aerial photographs of the prototype courtesy of Google Maps
Photos of the model: © Brian Satterlee