Indian Mill Bridge Rehab
Wyandot County, OH United States | 2015
The Albert Gravel Bridge is now at its 50-year milestone of service as one of the first fully hot-dip galvanized bridges in North America. Despite the well-known performance of galvanizing since the 1800’s, the first ever fully hot-dip galvanized bridge was only erected in 1963 and it is just down the road from this bridge.
A half century of proof positive corrosion protection from hot-dip galvanizing's zinc coating.
The Albert Gravel Bridge is an example of the "Pennsylvania" style of truss structure. When it was being designed in the late 60's engineers were acutely aware of the corrosion challenges that were accelerating at that time with expanded deicing practices required by postwar speed increases on roadways. Traditional paint on steel or cast concrete bridges required constant maintenance and even with all of this upkeep these bridges were degrading rapidly.
Nowhere was this more evident than in Quebec, The incredibly challenging corrosion environment for bridges here in Eastern Canada probably explains why the province of Quebec holds the distinction of pioneering hot-dip galvanized bridges. The Albert Gravel bridge couldn’t be in a better environment to test the mettle of HDG. Brutally cold winters, high humidity the rest of the year, De-icing road salts spread incessantly on the road and sidewalk surfaces for about six months of every year, heavy applications of sand and other traction enhancers that both erode surfaces and trap salt laced moisture wherever they accumulate.
This corrosive mess is sprayed around the entire structure by almost 3,000,000 vehicle crossing per year but yet despite all these challenges galvanized steel exceeded all expectations with almost no degradation after 50 years of use and abuse. That this amazing performance could be achieved with a solution that costs no more and often less than vastly inferior traditional paint systems is an incredible testament to the unparalleled value equation of hot-dip galvanizing.
The amazing performance of galvanized steel on the Albert Gravel Bridge and the others built near it in the 1960's clearly document the superiority of HDG as a cost effective corrosion solution. Fifty years on it is still the solution of choice and hundreds and hundreds of newer bridges built right up to this year are equally well protected by hot-dip galvanizing!
According to engineer Ghislain Boucher of the bridge owner, the provincial roads department (MTQ), a recent inspection (2018) after 48 years of maintenance free service showed almost no degradation of the original galvanized coating on the steel structure. Only minor areas of coating reduction were noted on the extremely corrosion prone lower cords where they meet the deck, but even in these areas zinc coatings still meet minimum average coating thickness requirements for new fabrication. This 48 years of maintenance-free corrosion protection far exceeded the expectations of the MTQ. The previous painted bridge at this location had required nearly perpetual corrosion repair and maintenance over it's service life.
|Desc||Read. 1||Read. 2||Read. 3||Read. 4||Read. 5||Avg.|
|Beam (height of the road)||314||287||360||373||478||362.40|
|Beam (height of a man)||249||235||319||232||220||251.00|
|Pedestrian crossing ramp (HSS square)||126||172||154||139||199||158.00|
|Beam in height (about 12 feet from the ground)||319||326||338||243||297||304.60|
|Interior of the beams (height of a man) H Beam||381||357||272||310||309||325.80|
Bromptonville, QC Canada
Coating Durability, Corrosion Performance, Initial Cost, Life-Cycle Cost
The entire bridge including all structure, guardrails etc
Ministère des Transports du Québec
Grandmont & Fils
Corbec - Montreal
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