The Johnson Street Bridge could be restricted to two slow lifts a day for several more days, says city engineer Fraser Work.
Typically the bridge would be lifted an average of three or four times a day for marine traffic, he said.
Out of “an abundance of caution,” a decision was made not to lift the bridge at all for much of last Thursday and Friday, after there was a high-pressure indication in the hydraulic system.
After working on the system all week, city crews were taking additional steps Friday to clean the hydraulic oil, Work said. “We’re not worried that we’re going to have some long-standing issue or anything.”
He said the bridge is operating “well and as designed” and there has been no indication from its operations that something major is wrong.
“I’m not staring down the barrel of a huge, big maintenance burden or a huge, big replacement of gear or equipment. No one is talking about anything like that. It’s just about proving the system is working the right way and making sure we get the confidence back in the system,” he said.
The issue was discovered during the first maintenance routine since the bridge came into operation, Work said.
“Essentially, the indicator in the system said the pressure it’s taking to get the oil through has changed and it’s at its limits, so now’s the time to change the filters,” Work said.
That was done, but after the oil was inspected, a decision was made to further clean it, Work said, “We’re ensuring that the oil is clean by running it through an external set of filters and double polishing it, to make sure that it’s safe and sound,” he said.
“Because those systems run at such high pressures and they are so important to the overall health and the longevity of those components, we just said: ‘Let’s go to a slower-speed operation which has less pressure and let’s do that until we prove that the system is doing exactly what it needs to do and the filters are working exactly how they need to work,’ ” Work said.
The $105-million bridge officially opened in March 2018.
“If all goes well today [Friday], we’ll likely move to an unrestricted number of lifts per day based on the needs of the marine community,” Work said.
“Potentially, we’ll still operate in the slow mode and then beyond that we’re going to have to wait and assess that with [bridge constructor] PCL and the system manufacturer.”