The Sault Ste. Marie Bridge Authority (SSMBA) board of directors, the bi-national body that supervises operations of the International Bridge, heard reports on bridge inspections at the board’s regular meeting yesterday.
The SSMBA board reviewed and officially accepted the results of the annual bridge, fracture critical, and underwater inspections. A team of bridge engineering experts from the lead firm of Hardesty and Hanover (H&H) of Okemos, Mich., along with MMM Group of Mississauga, Ontario, conducted the two-week-long annual inspections of the bridge this fall and presented their findings at today’s meeting.
“The bridge’s ongoing maintenance is outstanding, keeping the overall condition of the bridge good to fair,” said H&H structural engineer Richard Wianecki. “Our inspection found no significant changes from previous years.”
H&H noted some minor items that the International Bridge Administration (IBA) staff has included in scheduled maintenance for 2020.
The fracture critical inspection was conducted on the U.S. half of the bridge. These inspections, conducted on one-half of the bridge each year, provide a closer look at bridge components that are critical to the structural integrity of the bridge.
Great Lakes Engineering Group presented the findings of their underwater inspection. This inspection examined the bridge piers below the water line in the St. Marys River. The inspection, performed by qualified divers and engineers using scuba gear and sensors, probed and recorded the condition of the piers. The inspection is mandated by the Federal National Bridge Inspection Standards (NBIS) and must be performed every five years. The last inspection, originally scheduled for 2014, was postponed due to high water flow and conducted instead in 2015. This year’s inspection returns the bridge to its previous five-year schedule.
“The underwater components of the bridge were found to be in good to fair condition,” said Casey Collings of Great Lakes Engineering Group. “None of the findings of the underwater inspection are considered to negatively impact the structural integrity of the bridge.”
“The IBA has a track record of outstanding bridge maintenance,” said Karl Hansen, the IBA bridge engineer. “Our staff is dedicated to protecting the public investment in the bridge. We repair any structural deficiencies, no matter how minor, found during these inspections.”
In other business, the board heard updates on major maintenance projects completed this construction season.
Several previous bridge inspections identified an area of concern at the top of bridge piers 19 and 20. Cracks had formed, allowing moisture to enter the surface, resulting in deterioration of the concrete pier tops. H&H recommended removing and replacing the delaminated concrete, recapping a portion of the pier top. That work posed some challenges: the pier tops are about 100 feet above the river and it is a complex location for performing cleaning and concrete repair.
While not originally scheduled this year, work on pier 20 began in mid-August and was completed in early October. The total cost of the project utilizing IBA maintenance staff was about $26,000. H&H estimated the cost of performing this work with contracted services at approximately $203,000, an estimated savings of $177,000. Based on the success of this project, Pier 19 will be scheduled for repair in 2020.
In addition to the pier repairs, routine maintenance and yearly activities, some other highlights of the work IBA staff completed this year include:
· Bridge deck – After a high concentration of hairline cracks was identified on some parts of the bridge deck, crews treated the areas with “flood coat” and aggregate to ensure all cracks have been sealed against water infiltration and to make future routine crack sealing more efficient. This year, just more than 35,000 square feet of deck was treated, bringing the total deck surface coated up to more than 134,000 square feet.
· Painting – A total of 560 feet of the bridge’s ivory curb rail was cleaned and coated during 2019. To date, about 4,292 linear feet of ivory curb rail has been cleaned and coated with a high-ratio calcium sulfonate alkyd (HRCSA) one-coat paint system.
· Railings – Staff successfully replaced 17 of 20 green rail posts in 2019. These uprights were sandblasted and coated with the HRCSA paint. Another 20 posts were cleaned and coated.
· Expansion joints – Despite unfavorable fall weather, staff completed three of five planned retrofits of bridge expansion joints. Crews used a new system that helps prevent water collection on the substructure, mitigating corrosion of steel surfaces.
“We want to thank our inspection firms for their thorough scrutiny of the bridge, and the IBA staff for the great work they’ve accomplished this year,” said Hansen. “The bridge has realized enormous benefits from completing a wide array of maintenance work in-house. This has allowed us to be flexible and incorporate innovations while saving money.”