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Falling off a bridge is a horrific event that truck drivers don't want to happen. But during the commute, it can be easy to forget what prevents bridge traffic from going over the edge: concrete barriers. One Ryerson researcher, however, knows these crucial safety devices need to be improved - and the solution, he has found, is as clear as glass.

Khaled Sennah, chair of the Department of Civil Engineering says bridges built before the 1970s did not use frost-resistant concrete and coated reinforcing steel bars to protect from the effects of freeze-thaw cycles and the application of winter de-icing salt. "This has contributed to corrosion-induced degradation in bridge elements and can lead to reduced performance over time," says Sennah.

Exposed bridge elements likely require expensive replacement on the majority of older bridges. In fact, it is estimated that over 40 per cent of all bridges in Canada are older than 40 years, and require rehabilitation or replacement. The backlog of maintenance, rehabilitation and replacement of highway bridges is estimated to cost $10 billion, and the process of rehabilitating and/or replacing bridges takes a considerable amount of time.  

Safety of these older bridges is also a concern. For example, a 2007 report by the Residential and Civil Construction Alliance of Ontario warned that the integrity of Ontario's municipal bridge infrastructure and public safety are at risk after years of deferred maintenance, irregular inspections and lack of government oversight. Indeed, Sennah says media coverage of bridge collapses in Quebec and Minnesota in recent years has highlighted the serious consequences of postponing actions to rehabilitate or reconstruct deteriorated bridges, and the urgent need to take action to safeguard the public from potential infrastructure failure.

To that end, Sennah's research team has conducted research to promote bridge engineering designs that improve bridges' life expectancy and reduce maintenance costs, thereby optimizing taxpayers' money. He says rust-free glass-fibre-reinforced polymer (GFRP) bars are the best solution. Estimated to cost 15 to 20 per cent more than traditional concrete barriers, GFRP barricades require no maintenance and have an estimated design life of 75 years. Other barriers, meanwhile, must be replaced every 20 to 30 years.

Between 2008 and 2010, Sennah verified the GFRP-reinforced barrier's strength and ability to absorb vehicle impact while using full-scale barrier models in Ryerson's Structures Laboratory. Sennah's research team also conducted the first North American crash test on a performance level three (PL-3) concrete traffic barrier reinforced with GFRP bars. The 2010 crash test, which was conducted at the Texas Transportation Institute (TTI) with funding from Schoeck Canada Inc. (a German GFRP manufacturer), involved a 36,000 kg gross weight tractor-trailer. Travelling at a speed of 80 km/hour, the test vehicle hit the barrier at a 15-degree angle (watch the crash here: http://youtu.be/ilOfKSGWju0).

During and after the collision, the truck remained upright, and did not penetrate or roll over the barrier. In addition, no part of the barrier became detached during the accident, which would save drivers, passengers (and others in the area) from injury and possible death. Finally, only minor cracks were observed on both sides of the barrier - a problem that could be repaired easily.

Based on the crash test and associated push tests to complete-collapse conducted by Sennah's research team, the Ontario Ministry of Transportation (MTO) has developed and released a MTO standard drawing for PL-3 barriers reinforced with GFRP bars. The specifications are for use in future Ontario construction contracts.

In 2011, as a continuation of his partnership with the MTO, Sennah and his research team successfully conducted the second North American crash test on a bridge barrier - this time, reinforced with GFRP bars produced by Pultrall Inc. of Quebec. The test, which was conducted at the TTI, received funding from Pultrall Inc. and the Government of Quebec Consortium De Recherche En Plasturgie Et Composites Du Quebec  (view the crash here: http://youtu.be/i-JVVJYK2Co).