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McIntosh Perry

Accelerated Bridge Construction and its Advantages

Trio of McIntosh Perry engineers takes top CSCE prize for bridge innovation

Prior to joining McIntosh Perry, he was head of the MTO Structural Research section of the provincial Bridge Office. He and Tharmabala, now the head of the Bridge Engineering Office of McIntosh Perry in Burlington after serving as manager of MTO’s Bridge Office, started proving the project could be applied by performing initial tests at the MTO bridge laboratory in Toronto more than 10 years ago. Islam, who has 38 years of bridge engineering experience working with MTO and consulting engineering firms, also joined the McIntosh Perry team in January. He is working out of the Kingston office as the managing engineer for the MTO Bridge Design Team.

“We started lab testing scale models in 2001, as part of our research work,” said Lam. “That helped us gain enough confidence to try it in the real world,” he said. In 2005, the first truly pre-fab bridge was constructed near Timmins, Ont.

Lam said there is a huge benefit to accelerating construction. The conventional way of building and replacing bridges can span more than one construction season (year), with traditional construction using a staged process in order to maintain traffic. The project team developed a system replacement in which the bridge is actually built off-site and put in place within a matter of hours – shifting the construction paradigm to actually close the bridge site for a time.

“This way, you’re only handicapped for one weekend,” Lam said. “It’s short-term pain for long-term gain. You’ve just replaced two years of headaches with one weekend.”

Lam said there are many benefits to this method: environmental benefits in terms of reducing carbon emissions during long traffic delays, safety considerations when staging construction next to live traffic for long periods of time, as well as societal impact. In fact, the award entry form states that by implementing ABC and pre-fabrication, the Ministry has been able to reduce construction duration, traffic congestion and user costs.

“Studies have shown that the user costs of traffic delays in North America run into the hundreds of millions, if not billions,” Lam said, noting that residents around a bridge replacement site also benefit from accelerated construction.


Three engineers with McIntosh Perry are being honoured nationally for their roles in advancing the way bridges are constructed and replaced in Ontario.

Clifford Lam, Quazi Islam and Bala Tharmabala, are part of a team receiving a Canadian Society for Civil Engineering Excellence in Innovation in Civil Engineering award at the end of May for their contributions to the evolution of prefabrication and accelerated bridge construction (ABC) over the past decade, while working with Ontario’s Ministry of Transportation (MTO).

Lam, who joined McIntosh Perry as a senior engineer in January after 30 years of bridge engineering service with the Ministry, submitted the award entry form. He said winning the award gives the entire team who worked on the evolving project a sense of professional satisfaction. “It’s nice to be recognized by your peers – told that you have achieved something beneficial,” he said.

The entry form notes that the evolution of ABC has occurred along two themes, using prefabrication and traditional equipment to replace entire bridges in a matter of weeks, and secondly, the ability to replace bridge superstructures in less than 24 hours. Lam said this translates into a significant societal benefit by drastically reducing the duration of construction, traffic congestion and delays to the travelling public.

On the project, Lam and Tharmabala, who joined McIntosh Perry as Head of Bridge Engineering Office in January 2012 after 29 years of bridge engineering experience with the ministry, were responsible for the initial R&D work to develop a workable prefab bridge system through an extensive laboratory testing program. In addition, they also championed the first prefabricated bridge in Canada. Islam championed heavy lift projects in the Ottawa Queensway and successfully completed the first weekend bridge replacement in Canada. As such, they played a pivotal part in the development and implementation of the prefabricated bridge technology currently used by the Ministry to accelerate bridge construction in the province.

Lam is now a member of the McIntosh Perry MTO Design Group and is focusing on MTO design work and design build work in additional to municipal engineering.        

“Three days of road closures versus years of delays saves so many hassles, that from a resident perspective the benefits speak for themselves.”

Another advantage to pre-fabricating bridges is being realized in remote regions of the province. “In those areas the closest ready-mix plant could be 100 miles away,” Lam said. “Bridges were having durability problems because of difficulties in obtaining reliable and good-quality material.” Pre-fabrication in this sense means that the bridge would be built in the south and transported to the remoter sites, essentially providing a better product while offering more quality control.

He admits that in the beginning of the process they met resistance and struggled to get people on board with their vision for accelerated bridge construction. “We had to be persistent,” he said. “But after the first one was built, that successful trial showed that it could be done – and it could be done faster.”

Lam acknowledges that moving forward, the old-fashioned way can still work and is still beneficial depending on circumstances. But he knows that there is now a growing trend towards using the new pre-fab methods, noting the idea has taken root. “The use of this type of construction is getting more attractive,” he said.

The CSCE award entry form notes that the successes of various ABC projects will create future opportunities to reduce the impact of construction on society. “The demographics of bridges in North America necessitate a growing number of bridge replacements over the next 20 years or more,” Lam wrote in the form.

Lam, Tharmabala and Islam will receive their awards at the CSCE awards banquet in Montreal on May 31.


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