Car under Lions Gate Bridge - 1982
From hEUStory
Reprinted from The UBC Engineer, 1982
Contents |
An Engineering Experiment
(or How to hang a Volkswagen under a Bridge)
By Alan Burgess
A stunt is commonly defined as a feat displaying notable skill and strength. An Engineering stunt such as hanging a car beneath the Lion's gate Bridge requires careful planning and design. In order to be sanctioned by the Engineering Undergraduate Society, a stunt must not endanger life or damage property. The following narration of the Lion's Gate Stunt illustrates the planning and thought that made this stunt successful.
CONCEPTION
In October 1981, a group of students suggested that a shell of a car be hung, beneath the Lion's Gate Bridge. A reconnaissance of the bridge was subsequently done in mid October. At that time, four students ventured to the base of the main structure on the North Vancouver side. They climbed down from the deck of the bridge into a maintenance platform in order to study the deck’s construction. From the platform, the students noted that a cable could be looped around the main floor beam or be fastened to the box beams which ran down each side. It was decided that the project was feasible. Preliminary plans were formulated before being temporarily shelved pending final approval.
PREPARATION
The project was finally approved in mid-January. A group of students were assigned the task of finding a suitable car. After spending an unsuccessful day rummaging through wrecking yards, they tried the 'Buy and Sell', which listed used automobiles, and were successful in finding a red VW beetle shell complete with four wheels. After purchasing the VW, the car was then towed to an undisclosed private garage a mile from the north end of the bridge.
The preliminary plans called for the car being attached to cables beneath the bridge, and then pushed over the side. The students involved in the stunt consulted a group of practicing engineers who suggested that if the car was too heavy and fell too far, a beam could be bent or the cable could snap, sending the car into the harbour. The problem of weight was resolved by careful stripping and cutting of the car-body until it weighed under 800 pounds.
The problem of the length of drop was resolved by using two cables. One cable was to be connected to either side of the deck and a second cable was to be attached to this spanning cable and the car. When the car dropped, it would drop the distance of the second cable and slide into the middle of the spanning cable. The spanning cable would transfer part of the impact into compression on the deck, rather than bending in the bridge beams.
EXECUTION
The stunt was executed over two consecutive nights. On the first night, the spanning cable was attached. Around 4:00 a.m. when the bridge traffic was sparse, a group of students were dropped off beside a lookout on the bridge. The students ventured over the guard rail and fastened one end of a half inch cable to a box beam using three aluminum cable clamps. Then one student put on a safety harness and crawled beneath the deck along a cross beam. Once across this beam, the student pulled the cables across to the other side where it was attached in the same way.
The second night, a system of cables were attached to the car's frame, and spliced over the estimated center of mass of the shell. The car was towed to Stanley Park and eight students were dropped off on the bridge at the 'throw over' location. Because of an accident, the Vancouver City Police and the Highway's Department had blockaded the north bound lane and diverted the southbound traffic through Stanley Park about 250 meters away from the 'throw over' point. This allowed the students to pull into the traffic free north bound lane and tow the shell to the rendezvous point on the bridge. Within thirty seconds, the car was unhitched, the cable was attached to the spanning cable, and the car was lifted over the side to drop into place beneath the bridge.
The beams did not bend, the cables did not break, and the rest is public knowledge.
