State officials say they have found and solved the problem that caused five recent breakdowns that blocked the Craig Memorial Bridge to I-280 traffic. (Diagram of bridge problem)
But they caution that the bridge's 1950s-vintage electrical control system includes scores of contacts, switches, and relays that are vulnerable to failure and difficult to replace.
It took just one balky electrical switch to disable the bridge five times between March 27 and May 3.
“We're not expecting any more problems with this [switch],” said Gary Weinandy, the Ohio Department of Transportation's district highway management administrator. “But six weeks from now, another one could act up.”
During 1,938 bridge openings between 1997 and 2000, only 13 malfunctions occurred - a 99.4 percent success rate that is “good by anybody's book,” said Richard Martinko, ODOT's district deputy director at the Bowling Green office.
But he said even a flawless opening is a hassle for motorists, and a breakdown “just exacerbates the situation.”
The Craig has become disabled six times since March 26 - almost half as many times as during the previous four years - forcing I-280 traffic to detour through downtown Toledo streets. Last year, an average of 63,000 vehicles used the bridge each day, including 11,930 trucks.
“It's really difficult with all the trucks, because they can't use the King bridge,” said Toledo police Lt. Louis Borucki, head of the department's traffic section. “It saps our manpower quite a bit, especially when the bridge breaks down during the afternoon rush hour.”
The March 26 breakdown, which occurred during the predawn hours, involved a problem with the bridge's center locks that was corrected within 21 minutes and caused only minor traffic delays.
But the next afternoon, the bridge was closed for three hours when an electrical circuit, which allows safety gates to go up once the draw spans are properly lowered, would not connect. On four subsequent occasions - most recently May 3 - one half of the bridge remained in the upright position because a circuit failure kept the brakes that held that draw span in place from releasing.
Both problems were traced to an electro-mechanical switch that completes one circuit when the bridge is down and another circuit when the bridge is up, Mr. Martinko said.
The reason the problem took so long to find, he said, was that after the first brake-release breakdown April 6, the switch and its counterpart on the other half of the bridge were replaced, and one of the new ones proved defective.
“We were saying, `It can't be the switch, we just replaced the switch,'” Mr. Martinko said. “So we thought the problem had to be with the brakes themselves.”
Electricians discovered that a plunger that throws the switch sometimes stuck in the compressed position, which caused the bridge's brakes to malfunction.
ODOT is having the bridge's original, spring-equipped switches reconditioned so they can be put back in place, Mr. Martinko said. In the interim, an electrician is called to supervise each bridge opening so that any problems with the replacement switches can be corrected quickly. All bridge tests are being done late at night to minimize traffic problems.
The ultimate solution to the Craig bridge's problems would be to replace most of its controls with a modern, solid-state system, Mr. Weinandy said. But that would require disabling the lift mechanism for a period of months and closing it to motorists, because river traffic legally cannot be blocked.
Computerizing the bridge “would be a nightmare - it would take probably a year to shake it out. And you can't do that as long as it's part of the interstate system,” agreed Jim Bradley, an ODOT bridge engineer.
But once a new, high-level I-280 bridge opens in 2004, the Craig will become a local bridge, and a long-term closing to replace the control system will be feasible, Mr. Weinandy said.