Bridge Operation Willamette River Swing Truss Railroad Bridge, Portland Oregon
Bridge communications and signals between the operators and the trainmasters and with river traffic has been modernized. Except for the signal system and derail operations, which are still manually operated from the bridge, most communications are now by telephone and radio. A double air horn signal is still used to give warnings of impending opening or closing of the draw and to signal operating troubles and opening and closing delays. Most river traffic now requests that the draw be swung by means of VHP radio-telephone, and information on train movements similarly comes by radio. Bridge 5.1's whistle signal is one long and one short blast.
Railroad safety rules and U. S. Coast Guard rules govern the operation of the bridge and the conduct of its operators. The record indicates that there have been regular improvements made in the bridge's clearance lighting and marker lights throughout the years. Lighting has changed from kerosene lamp fixtures to incandescent electric lighting (exact date not recorded). According to Burlington Northern Railroad Company Timetable and Special Instructions No. 5 October 1984, maximum speeds on the bridge are 25 MPH for passenger cars and 15 MPH for freight trains. Trains frequently cross the bridge in both directions at the same time. The present Coast Guard permit and rules require that the bridge be attended by an operator at all times, A single operator is on duty each of three shifts per day. A helper is on duty four days a week to perform the routine lubrication of the machinery and maintenance work. The helper is also a relief operator for one day, rotating as needed between the three draws of the Vancouver-Portland bridge system.
Bridgetenders are usually non-specialists who have been hired for the job after progressing from other railroad maintenance positions. Training as an electrician is considered to be desirable but not essential. Operators appear to have been trained for the tending job by observing other operators and on-the-job experience. The job is a lonely one, uneventful at best and accented by pure terror at the worst. Some operators spend the time reading. Watching from their high perch and seeing the seasons and weathers change are reported to be some of the rewards of the job; sunrises over the Cascade Mountains to the east are said to be especially dramatic from this viewpoint. Operators become familiar with the regular ships and towboats and their crews who pass through the draw. One operator reportedly completed his studies for college credits during his shifts. Their regular duties include recording information on all significant traffic through and across the bridge and reporting on all accidents and on the bridge's condition. Accident reports include notes on the time, weather condition, and visibility when the event occurred. Operators give their interpretation of any cause or fault in an accident. Except for the helper during the day, there are few visitors to the Bridgetender's house.
Bridge operation is relatively simple. When the operator receives either a signal or radio telephone request from the trainmaster in Vancouver to swing the draw, he knows whether or not a train is due to cross during the time the draw would be open. If a scheduled passenger train is in the immediate vicinity or if another train is so close as to be difficult to stop, the operator will determine whether or not the requesting vessel can be slowed or stopped to permit the train to cross before opening the draw for the river traffic. The VHF radio telephone usually gives the operator long advance notice of a request to swing. Smaller vessels which do not have radio-phones are usually able to stop or circle while waiting for a train passage. Whenever possible, precedence is given to river traffic over trains.
Before opening the draw, the operator acknowledges the signal or phone request and sounds his horn. He must first reset the signals to indicate no passage over the bridge and open the derails. The rail locks and shore boxes (signal connectors are withdrawn). The ends are unlocked and the jacks retracted. The draw motors can then be energized to swing the draw. A stepping resister circuit, located in a wire mesh enclosed rack in the northeast corner of the control room, is used to regulate the speed of the motors. As the span is swinging, its momentum is used to continue the opening or closing, and the motors are turned off. Carefully judged timing of motor cutoff can bring the draw to its stopping point over the draw protection or the end support piers with little use of the air brakes. When motors are off and the bridge is "coasting," there is a remarkable sound of meshing gears and inertia driven motors, accented with occasional pulses of gear train backlash.
Under emergency conditions, when one or two motors fail or other mechanical difficulty, the bridge can be swung with only one motor or by manually engaging the auxiliary motor by sliding its drive pinion on its splined shaft. The duplexed drive system was designed so that any one of the four bull shafts could swing the bridge if necessary, although they all operate simultaneously under normal conditions.