Friday’s heat in the mid-90s requires that the University Bridge take frequent cold showers to protect its steel decks from excessive thermal expansion that could prevent the bridge from being opened for boat traffic.
A sprayer truck will spend about 10 minutes of every hour soaking the bridge Friday, causing a temporary closure to motor vehicle. Crews will frequently measure the bridge midpoint between the two drawspans to ensure there is at least a half-inch gap.
The city hopes the all-day sprinklings on Friday will keep the gap wide enough to skip a rush-hour bath that stalled traffic around 5:30 p.m. Thursday.
Though the Ballard, Fremont and Montlake bridges also have steel components, it’s only at University Bridge that expansion has played havoc with openings, said Seattle Department of Transportation spokeswoman Marybeth Turner.
Bicyclists and motorcyclists are urged to beware of wet surfaces after each sprinkling.