Research Paper Points to Major Infrastructure Deficit In Saskatchewan

Deteriorated state of an in-service steel culvert

A research paper presented at the Transportation Association of Canada Annual Conference in Halifax in September 2010 points to a major and growing infrastructure deficit in Saskatchewan.

The Saskatchewan Ministry of Highways and Infrastructure (SMHI) is responsible for approximately 65,000 culverts that provide critical drainage and water control for the provincial highway network. The majority of existing culverts in the province are corrugated steel pipe (CSP). Under normal field conditions, the authors state that CSP culverts have a design life of approximately 30 years. The authors of the report estimate that seventy per cent of SHMI culverts are past their design life. This equates to an astounding 45,000 culverts.

Culverts are an integral component of the road system to manage water infiltration and prevent the flooding of roads. Also, culverts are critical to uphold the expected service life of the highway system. In addition to plugging or washing out, the deterioration of a culvert's performance results from many factors. Corrosion, most often at the invert of the culvert, is accelerated by humidity and moisture combined with freeze-thaw conditions. Also, reduced invert strength causes the culvert to scour and fail in demanding flow conditions. In addition, CSP connections can corrode or be pulled apart, which allows subbase and base cover materials to enter the pipe resulting in cavitations of the structure and a reduction in culvert flow capacity. Once pulled apart, water flow will create voids along the outside bedding of the pipe. There were significant voids underneath the highway that were identified in the Saskatchewan research.

In recent years, the need for functional drainage has been a significant Ministry budget issue with the pronounced increase in precipitation. In Saskatchewan, while some recent years have seen drought weather, others have seen exceptional precipitation. To illustrate, in 2010, Saskatchewan was subjected to higher than average precipitation. For the months of April, May, and June, the climate normal data from 1971-2009 for the Saskatoon area showed averages for monthly precipitation of 22.0 mm, 35.2 mm, and 69.8 mm respectively. In 2010 these averages for monthly precipitation were exceeded significantly, with Saskatoon seeing 72.6 mm, 128.5 mm, and 169.0 mm of precipitation in April, May and June respectively.

The presenter of the research paper in Halifax stated that the cost to reline a typical 600 mm CSP culvert with HDPE for a two-lane highway is approximately $20,000 and the cost to replace the same culvert is approximately $30,000. SMHI is subsequently facing a $1 billion to $1.5 billion infrastructure deficit in the area of culverts alone. With the province of Saskatchewan currently running a $1 billion budget deficit it is difficult to be optimistic that the necessary funds will be made available to fix this major problem.

The Ministry of Transportation of Ontario (MTO) is facing similar problems and challenges with culverts across Ontario. Ontario Concrete Pipe Association recently received thousands of culvert inspection reports and associated pictures of culverts underneath 400-series highways in Ontario. These reports and photos were obtained under the Freedom of Information and Protection of Privacy Act. It is estimated that MTO is responsible for at least 50,000 culverts and Ontario municipalities are responsible for a similar number. The vast majority of these culverts are CSP. Similar to the Saskatchewan experience CSP culverts are badly deteriorated after only 30 years. The province of Ontario is currently running a deficit close to $20 billion and like the Saskatchewan scenario, allocating funding for all these necessary replacements will present challenges. Ontario has the added problem of higher traffic counts. For example, the Average Daily Traffic (ADT) count on Highway 417 ranges between 15,000 ADT and 20,000 ADT on some sections. Traffic lanes on Highway 417 have been closed a number of times in the past three years due to collapsing steel culverts.

Ontario Concrete Pipe Association recognizes that there is a range of applications for drainage pipes made from all materials but asserts that not every product should be used in every application. Concrete pipe has a track record of being the most durable, dependable and safest drainage pipe used in Ontario and across Canada. This was confirmed by the information recently received under the Freedom of Information and Protection of Privacy Act. Budget deficits are here to stay, at least for the foreseeable future. Engineers and other decision makers need to think and plan longer term and solely specify concrete pipe under key transportation arteries in Ontario and other parts of Canada.

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