Don’t believe the signs at Maple garage

You shouldn’t believe the signs at Evanston’s Maple Avenue garage that claim the garage can accommodate an 8-foot-2-inch tall van.

You shouldn’t believe the signs at Evanston’s Maple Avenue garage that claim the garage can accommodate an 8-foot-2-inch tall van.

Engineering consultants hired by the city to check the condition of the city’s three downtown garages reported to the Parking and Transportation Committee Wednesday night that the actual clearance in the garage is just 7-feet-9-inches.

And to achieve even that clearance, the consultants say, somebody, at some point cut into concrete support beams in the structure, leaving metal reinforcing rods exposed to the elements.

Two adjacent ceiling beams in the garage, showing cuts in the concrete of the lower-hanging one that expose now-rusty metal reinforcing rods.

The consultants, from Halvorson and Partners Structural Engineers of Chicago, say that while the cuts probably don’t impair the structural integrity of the garage, the structural impact should be studied in more depth and the beams should be patched to provide a covering for the metal rods to reduce the chance of further corrosion.

Generally, the consultants said, the city’s garages are in reasonably good shape for their age, but they pointed out a variety of problems with corrosion of metal parts, cracking of concrete and infiltration of water and road salt into the structures that should be repaired.

The consultants estimate the repairs would cost close to $2.5 million, but they predict the work could double the remaining lifespan of the buildings.

The consultants estimated the current projected lifespan of the garages, if repairs are not made at 10 to 15 years for the Church Street and Maple Avenue garages and 25 to 30 years for Sherman Plaza, the newest garage.  

About 60 percent of the repair cost would be to add waterproof membranes to the floors of several heavily used levels of the garages that don’t have such protection now.

The membranes keep road salt tracked into the garage on car tires from penetrating the concrete structure. Without the protection, the salt gradually destroys the structural strength of the concrete.

Committee member Jonathan Perman, the executive director of the Evanston Chamber of Commerce, said the high projected cost of maintaining the garages raises policy questions about whether the city should be in the business of owning and operating garages.

But the committee’s chair, Alderman Melissa Wynne, 3rd Ward, said the committee should come up with a priority list and timeline for making the repairs.

The city generates about $3 million a year in parking garage revenue.

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