The People Who Bring Bridges to Life

The new Samuel de Champlain bridge opened to traffic on two very important days. The northbound lanes heading into Montreal were opened on June 24th, when the province of Quebec celebrates Saint Jean Baptiste Day. The southbound lanes heading to Brossard opened on July 1st, when Canada celebrates the founding of the country.

View of the Samuel de Champlain Bridge (right), alongside the old Champlain Bridge (left).

These opening days are symbolic of how important the original Champlain bridge, and now the Samuel de Champlain bridge, are to North America. According to Infrastructure Canada, this bridge is crossed 50 million times each year (

This translates to approximately 140 000 vehicles per day, or 5 800 vehicles per hour, making the crossing one of the most important bridges in North America.

How does a 3.4 km long bridge, with a final price tag of around $4.5 billion, get built? A project of this scale requires an organized group of thousands of people to achieve such a feat of Engineering. For years these people have been spending their days, nights, and weekends, often in extreme temperatures and weather conditions, ensuring that each individual task gets done on time, and on budget. So, who are these everyday heros?

There are many different roles that need to be filled to complete a project of this scale. To understand the range of specialties needed, consider the following groups of professionals who have contributed to the project:

  • Construction workers: Build the bridge, piece by piece. Includes work on site and in fabrication shops.
  • Construction Engineer: Coordinate construction works on and off the jobsite, ensuring the safety and quality of the works.
  • Engineer of Record: Design the bridge by calculating the exact loading expected from traffic, and create a structural system that can carry these loads safely across the river.
  • Independent Engineer: Check the design of the Engineer of Record, and spot-check the on-site works.
  • Environmental Engineers: Create systems to protect the environment before, during and after construction.
  • Geotechnical Engineers: Verify the condition of the soil and rock to ensure the bridge can rest on solid foundations.
  • Durability Engineers: Ensure that all materials and methods used for construction are going to meet the durability requirements of the bridge, which includes 125 years with no major repair works.
  • Quality Control Engineers: Verify the quality of the materials being received on site, and ensuring the quality documentation is filed per project requirements.
  • Document Controllers: Coordinate and document millions of documents relating to every aspect of the project.
  • Owners Engineer: Develop the overall concept of the bridge prior to awarding the project, in coordination with the Architect.
  • Others: There are numerous other groups that participated in the project, including risk management, finance, law, asset management, etc.

Within these professions, there is a large variation in the types of tasks required. Consider the role of the Engineer of Record (EOR). For the Samuel de Champlain bridge, the EOR consisted of T.Y. Lin International, Systra-International Bridge Technologies, and SNC-Lavalin.

Members of the EOR field Engineering team. Photo credit ©Christian Fleury-CAPA pictures.

From the pre-bid works to final completion, the EOR is constantly engaged on a wide range of different roles to ensure that the bridge gets built according to the project agreement and all relevant design standards. These roles include, but are not limited to:

  • Help develop an estimate of the materials and cost of construction with the contractor, to provide a competitive bid to win the project.
  • When the project is awarded, use the project requirements, design criteria and design standards to determine the size, shape, material and connection of the entire bridge.
  • Independently check the work of the other partners in the EOR team, to ensure the quality and safety of the design.
  • Work with the contractor to verify the method of lifting and installing each of these pieces.
  • Provide construction site support to the contractor at every stage of the construction, as part of the certification process for the bridge.

After the many millions of hours worked on this bridge, there is one final product that will last for at least the next 125 years. That translates to more than 6.3 billion vehicles trips, most of which will be made by people who are not even born yet. This single projection highlights the magnitude of what has just been accomplished in Montreal.

The importance of every single person who contributed to the project cannot be overstated, and has helped deliver a bridge that Montreal, and Canada, can be truly proud of for generations.

Members of the EOR team attending the bridge’s opening ceremony on June 28, 2019.

Engineering Better Conferences

How conferences can provide more value to Engineers

Conferences provide a forum for industry experts to come together to discuss ideas and share progress. The traditional format of Engineering conferences resemble a series of lectures: speakers first present their work, after which the audience is allowed some time for questions. If the presentation runs too long, it comes out of the question period. This limits the academic potential of conferences, as Engineers are forced to sit and listen, while providing limited ideas or input.

Often, conferences are attended by the same people each year, and have evolved into a forum for embellishing accomplishments. Attendees are not likely to recall the size of the prefabricated element that was erected, nor is this information necessarily useful to them. However, if everyone at the conference engages in conversation about the innovative technique that was used to erect the panels, and how it could be improved, then attendees can gain value from the conference.

Question period at the CSCE SMSB 2018 Conference in Quebec.

In addition, more workshop type sessions should be developed to nurture curiosity and teamwork, in order to inspire one another. These workshops should first introduce the major theme, such as the use of high-performance concrete. Following this, Engineers should be given a problem that must be solved based on the theme of the workshop. Working through and discussing these problems will not only foster creativity in Engineers, but highlight new opportunities or tools that Engineers can use in their own practice.

Change needs to start at the conference organizational level. Organizers need to put less emphasis on big dinners, expensive evening events and venues. This in turn will reduce the cost of attending the conference, allowing more engineers from a broader range of backgrounds to attend. In addition, reducing the number of speakers will provide more time per session for open discussion. Each session should have some main topics of conversation, that are supplemented by specific projects from the chosen speakers. No rehearsed speeches, and no wordy PowerPoint slides. If conferences are able to foster good discussions, they can provide real value to attendees. This will then motivate more Engineers to attend, building a stronger and more knowledgeable community.

Have any thoughts on how conferences can be improved to provide more value for attendees? Please feel free to provide input in the comment section below!

Pushing the Boundaries of Bridge Construction

Humans have been building bridges for thousands of years. At first, they were built using trial and error. Recently, humans began to use math and physics to create bigger, safer, and more economical structures. Paired with new materials, economic prosperity, and the development of the Bridge Engineering profession, this has led to the creation of some truly magnificent structures.

When the Brooklyn Bridge was completed in 1883, it had the longest main span (distance between vertical supports) in the world.  Since then, this feat has been surpassed hundreds of times. In 1937, using the same type of support system, the Golden Gate Bridge was constructed with a main span that is 2.5 times longer than the Brooklyn Bridge. Around 60 years later, the Akashi Kaikyo bridge increased that by 1.5 times.

Akashi Kaikyo. The longest bridge in the world.

The five bridges with the longest mains spans in the world are presented in the below table. All of these are suspension bridges, similar to the Golden Gate and Brooklyn bridges.

List of Longest Bridges in the World. Source: Wikipedia.

The theoretical limit on the length of a suspension bridge is governed by the self-weight of the support cable and deck system.  Theoretically, the longest possible length of a suspension bridge, using present day materials, is approximately 5 km. This is 2.5 times longer than the longest bridge built to date. However, there are many practical restraints that would make the construction of such a long span nearly impossible.

In the past century, the materials and methods used for construction have developed at a slow pace, and there have been few significant changes in the general form of long span bridges. Some may believe that engineers have reached the peak performance of construction materials, while others may argue that the current base of knowledge is sufficient for the majority of bridges that society needs. So why would engineers continue to push the boundaries of bridge construction?

Because, we are engineers – and that’s what we do!

Engineers are always looking for ways to improve bridges, either by building them faster, cheaper, or safer. However, only a small group focus on a very interesting challenge – how to make them longer. In a recent paper (link to paper), an analytical model was developed using a numerical layout optimization procedure to study the theoretically optimal form that a very long span bridge should have. One of the most interesting concepts that comes out of this paper is the split-pylon form, presented below. This bridge is shown with a main span of 5 km, which is 2.5 times longer than the longest bridge ever built.

Optimized concept for a very long span bridge. Reproduced from Figure 5 of this paper.

This new structural form would be difficult to construct using present day techniques, as it may require significant temporary supports when erecting the split pylons. However, the final optimal form provides a brand-new artistic form for a bridge – similar to the forms that became popular after the development of suspension and cable stay bridges. This balance of engineering optimization and form need only find a balance with economy, to become a truly plausible option.

At the very least, this paper significantly adds to our understanding of how long span bridges can be built using present day materials. It also offers hope to the bridge engineering profession, and opens up many new potential problems, and exciting challenges, that we get to deal with.

Even if a bridge like this never gets built, it will help to inspire others to study the feasibility of new structural forms for long span bridges. And that, is very exciting!

Engineers: The Creators and Controllers of Risk

Engineers use scientific knowledge to push the boundaries of the physical world. but how risky is it?

Engineering is a very dynamic industry, and the scope of what engineers do constantly changes. At the core, Merriam-Webster defines engineering as:

“The application of science and mathematics by which the properties of matter and the sources of energy in nature are made useful to people”

This is an incredibly broad description that encapsulates many activities. From building bridges to space stations, engineers design and build the visible (and more recently the non-visible) world around us. What this definition does not convey is that an engineer’s job is understanding and taking on risk.

With every new bridge, the engineer of record uses their theoretical knowledge to design the structure to an acceptable level of safety. In modern times, this level of risk is defined in technical and regional design codes and specifications. In the past, however, the acceptable level of safety was defined based on the experience of the engineers involved. This has created some engineering folk tales, including one where clients were forcing engineers to stand underneath their new bridges during load tests. This ensures that the engineer is literally held accountable for any short-comings in the design. I have heard this tale in many different countries around the world, and hope it was not true!

Load test on a new bridge. Photo Credit:

In modern society, a governing body licenses engineers by region. For each project, the engineer takes on the responsibility to protect the investment and safety of the public, client, and all stakeholders. As a result,

“each engineer must walk a tight line between being a designer and a lawyer.”

Each and every decision that an engineer makes can impact cost, schedule, and safety. It is therefore imperative that engineers understand the scope of risk that they are taking on, with relation to the project agreement.

The Project Agreement – The Holy Book of Risk. Photo Credit:

This is something that engineers, both junior and senior, can struggle with. In design-build contracts, for example, it is imperative that the scope of risk is understood by everyone, and maintained throughout the duration of the project. However, these lines can often get blurred when quick decisions are needed. It is at times like these that engineers must use caution in how they respond to each question, as small changes in wording can significantly impact the level of risk that engineers are exposing themselves, and their companies, to.

Since understanding this aspect of engineering can often govern the way we work and interact with clients and the public, it is imperative that this be taught to engineers in school, and early on in their careers.

This will not only help protect the public by maintaining accountability for risk, it will also protect our engineering firms from taking on unnecessary risk.

Bridge Engineering – The Lost Art

Like many, I grew up fascinated with how things work – how they are put together, how they stay together, who makes them – and how I can become involved with them. After some research (with books, dial-up internet time was restricted so my father would not miss a call), I found out my true calling – to be an Engineer.

Of all the interesting and challenging engineering disciplines, I decided that I wanted to be a Bridge Engineer. To put it simply: we take a problem (river), add a requirement (need to cross said river), and come up with a solution (bridge). Believe it or not, in most cases designing the bridge and its components is not the hardest part – it’s having to build them fast, cheap, and sometimes beautiful (more on this last point later). As the American Civil Engineer, Arthur M. Wellington put it,

An engineer can do for a dollar what any fool can do for two.

This is the key to the engineering profession. We innovate to save society money, which increases the number of infrastructure projects, which leads to more innovation and cost-savings. It’s a wonderful cycle! But there is something that seems to be missing in the modern day definition of a Bridge Engineer. In the below image, we have a bridge. This was designed by an Engineer, and is a common form for a present day highway overpass – but not many people would refer to this bridge as beautiful.

Typical Concrete Bridge. Photo Credit: 570 News.

Many people believe that this can be solved, simply by adding a “Bridge Architect” to these projects. Indeed, the Ministry of Transportation of Ontario (MTO) has taken this to heart, by recently making it mandatory on some signature projects. The most famous example of this is the engineer turned architect, Santiago Calatrava. As shown below, he cares deeply of the artistic originality of his bridges.

The Peace Bridge. Photo Credit: Global News.

However, this all comes at a large price tag – which is always paid for by tax payers. For example, the Peace Bridge was built for $24.9 million, and construction was delayed by 1.5 years. In addition to the high initial cost, the city has needed to repair broken windows ($152 K) and install new lights ($700 K), partly due to design problems (read more: Calgary Herald). This seems to be a recurring issue with Calatrava projects (read more: D Magazine).

Luckily there is a solution, and it’s very simple – education. Engineers study long and hard for years to master the physics behind bridge structures. However, very little time is put aside to teach students how to use this knowledge to create beautiful structures. As engineer David Billington put it, the art of bridge engineering is to balance form, function and economy. If you need proof, consider the Salginatobel Bridge shown below, designed by Bridge Engineer Robert Maillart.

Salginatobel Bridge. Photo Credit: Structurae

This bridge was the cheapest solution submitted, and for this reason only, was it built. Because Maillart had studied both the physics and form of bridges, he was able to create this masterpiece. But this is an extreme case. Consider this simple flyover bridge in Ontario. It was clearly not designed to be a signature bridge – but the attention to detail and form paid by the Bridge Engineer resulted in both an economical and arguably beautiful structure.

Hwy 401 Flyover. Photo Credit: Ontario Ministry of Transportation

Therefore, it is essential that bridge engineers stop selling their services as a commodity, and start re-discovering the influence that a good Bridge Engineer can have on society.

This must start in the classroom.

Why we need a New Champlain Bridge

The new Champlain Bridge corridor project in Montreal, Canada will cost up to $4.5 billion, and is planned for completion on December 1, 2018. But what’s wrong with the current bridge? Why was the decision made to build a new one, with such a large price tag?

Main span of the existing Champlain Bridge

Spark-Notes (Easy Read)

This section provides a quick, non-technical summary of this post. For more details, including some more technical information, continue to the following section.

  • Current Champlain Bridge, open to traffic in 1962.
  • Designed by engineers at SNC.
  • Designated a life-line route off the island during emergencies.
  • A 2011 report found that the main span was in good condition, but the concrete girders were deteriorating faster then expected.
  • If one of these beams fails, the bridge could collapse.

If the new bridge is finished on time, experts predict that a total of $550 million will have been spent on repairs. In October 2017, experts announced that it would cost an additional $250 million to keep the current bridge in service until 2020.

As a result of this assessment, and after years of discussions, the government of Canada finally decided to proceed with  construction of the new Champlain Bridge. Stay tuned for a future post on the construction of the New Champlain Bridge!

Detailed Notes (Technical)

This section provides more details and technical information, expanding on the points discussed in the spark-notes section.

Condition of the existing bridge

For years, experts were discussing potential options for repairing or replacing the existing bridge. However, the findings from the study conducted by the engineering firm Delcan (see full report) was the catalyst that started the process of designing and building the new bridge. The study was commissioned in August of 2010 to determine the current state of the Champlain Bridge. Although the bridge is considered a lifeline for the island of Montreal, it was found that the bridge would not be able to withstand extreme seismic events.

Prestressed Concrete Girders on Champlain Bridge

The steel main span superstructure was found to be in relatively good condition, but the prestressed concrete girders, used for the approach spans, exhibited significant deterioration from the salt water running off the bridge roadway. The condition of the steel reinforcement in these girders cannot be determined, due to the potential dangers of damaging the pre-stressed strands. However, there is evidence of damaged and broken strands inside the concrete. The report also found that failure of the edge girders could lead to the progressive collapse of the bridge.

Steel truss under edge girders

These findings confirmed that critical repair work was needed on the existing bridge in order to maintain its safety in service. However, the cost to repair the bridge over the next 40 years was found to be equal to the cost to maintain the existing bridge for 15 years while building a new bridge. This point made it very clear to all parties involved that a new bridge was needed – and fast.

Repair work needed

At first glance, the current Champlain bridge looks like it is using every bridge rehabilitation technique ever invented. For civil engineering students at the city’s various universities, it would be a perfect case study, and an easy field trip.

External post-tensioning installed on pier caps

Sensors have been placed across the length of the entire bridge, to monitor its behaviour and deflection during service. In addition, the following repair techniques have been applied:

  • A total of 74 steel truss supports have been installed under concrete edge girders, found to be in critical condition.
  • External post-tensioning applied longitudinally along the edge girders.
  • External post-tensioning applied transversely along the pier caps.
  • External fibre reinforced polymer (FRP) wrap applied applied to the exterior of many girders.

View of repair work done on edge girders

Assuming that the new bridge is delivered on schedule, the total repair bill is expected to reach $550 million (CBC).  But with the majority of repairs completed on the existing bridge, and the new bridge planned for completion in December 2018, it seems that Montrealers can rest assured:

The life-line crossing across the Saint Lawrence – one of the busiest bridges in Canada – will continue to be a safe choice for everyone.

For more photos, visit: Existing Champlain Bridge Photo Album

For more information, see below resources:

Revolutionizing the Bridge Replacement Industry

The goal of every bridge replacement project is to minimize traffic disruption. Although this can be achieved using temporary structures, it results in high construction costs. More recently, modular construction has been used to cut down the on-site construction time. However this method still significantly impacts traffic flow.

A new technique, known as Accelerated Bridge Construction (ABC), has been developed to mitigate traffic disruption. This process begins with the construction of the new bridge superstructure alongside the existing bridge. Once this is completed, the existing bridge is quickly demolished and the new bridge is slid into place. The final few pieces are installed, and the bridge can quickly reopen to traffic with minimal disruption. This procedure is outlined in detail by the Iowa Department of Transportation:

There are a number of projects throughout the United States that are using this new technique.

Michigan’s Department of Transportation (MDOT) is finalizing plans to replace three bridges this year using this process (M Live). MDOT spokesperson John Richard stated, “You’ll definitely see a lot more bridge slides taking place just because of the less impact on traffic. It’s really changing the industry. All the engineers at MDOT are very excited” (M Live).

New York’s Department of Transportation has already constructed a number of bridges using this process. The construction of the I-84 bridges, which began in June, was completed in October of last year. Despite the length of the project, the actual replacement time totaled 18 hours for each bridge, occurring over two weekends. This resulted in savings of $4 million dollars (Roads Bridges). You can view the time lapse construction video of the bridge here: Accelerated Bridge Replacement

Replacement of the I-84 Bridge in New York. Photo Credit: Wired

It is evident that the use of ABC as a bridge replacement technique will increase in the coming years. However, it is important that researchers around the world continue to develop more efficient ways to replace the  worlds ageing infrastructure. This includes reducing construction time, reducing costs, mitigating the effects on traffic and recycling materials from the demolished bridges.

For more information regarding ABC see the brochures recently published by Aspire Bridge:

Part 1 – Winter 2013

Part 2 – Spring 2013

Part 3 – Summer 2013

The Great White “Vanilla” North

On October 27, the well known street artist Banksy posted a short piece on his blog describing the new One World Trade Centre building as “Vanilla”. Banksy claims that the new tower is a betrayal to those that lost their lives on September 11. The backlash was swift as numerous news outlets, including the BBC and the NY Daily News, have criticized the article. One of the comments Banksy makes is that the new tower is “something they would build in Canada”. But does this statement have any merit? Is Canada’s architecture something to mock?

Oh Canada

Having claimed the title of the worlds tallest tower for 34 years, the CN Tower has garnered both praise and criticism. On the one hand, it attracts millions of tourists each year, and is one of the top attractions in the country. On the other hand, critics have often identified the tower as an eyesore. Colin Vaughan, an architect and political specialist for CityTV from 1977 to his passing in 2000, claimed:

“The first disappointment comes at the main entrance. There’s no sensation of arriving at the base of a tall structure to be overwhelmed by the vision of the tower ahead… But none will experience the unique sensation, the vertigo and the straight excitement which should accompany a visit to a structure of this scale” (TorontoIST).

Toronto’s CN Tower. Photo Credit: CBC

This aside, the CN Tower is one of the American Civil Engineering Societies Seven Wonders of the World and is second place in the world federation of towers (CN Tower). There can be no doubt, this icon is a masterpiece that has put Canada on the map.

Award Winning Architecture

According to the official website, the Emporis Skyscraper Award is the world’s most renowned prize for high-rise architecture and has been awarded on an international basis every year since 2000. In 2012, the Emporis Skyscraper Award was given to the Absolute World Towers (also known as the Marilyn Manroe Towers) in Mississauga, Ontario (Emporis).

The Bow building in Calgary, Alberta is the tallest office building in Canada outside of Toronto.  In 2012, it finished fourth in the Emporis Skyscrapper Award and was also ranked in the top ten architectural projects of 2012 by Azure Magazine (Azure).

Bridges Eh?

Canada is also home to some truly spectacular bridges. The Peace Bridge in Calgary, Alberta was ranked in the top ten architectural projects of 2012 by Azure Magazine. In addition, CCN composed a list of the top 24 most spectacular bridges in the world, and both the New Brunswick Hartland Bridge and Confederation Bridge in Prince Edward Island were among them (CNN)

Producing World-Renowned Architects

Canadians can also be proud of the fact that many esteemed architects around the world are Canadian. Frank Gehry was born in Toronto and was revered by Vanity Fare as the most important architect of our age (Vanity Fair). Gehry has designed iconic buildings around the globe, including the famous Guggenheim Museum in Bilbao, Spain. Back in Canada, he designed the new addition to the Art Gallery of Ontario, which has been given outstanding reviews by architects around the globe (NY Times).

The Renovated Art Gallery of Ontario. Photo Credit: Jamie Sarner

Final Thought

As Canadians, we all agree that everyone is entitled to their own opinion. I will not say that Banksy should take back what he said, nor will I attack him as an artist for having an opinion. However, this article has provided you with enough information to allow you to formulate your own opinion regarding the amount of “vanilla” architecture in Canada. There is much to be proud of as Canadians, and I believe that the quality of architecture in Canada is something that speaks for itself.

For an indepth look at various other Canadian masterpieces, see the recent article by The Glove and Mail.

2013 New York City Bridge Conference

On August 26th and 27th, the world’s top bridge engineers and architects congregated to New York City for the 2013 New York City Bridge Conference. This conference was first hosted by the Bridge Engineering Association in 2003, but has quickly emerged as one of the leading bridge conferences in the world.

This year, the conference played host to a number of esteemed guests and industry leaders. The lead designer for Istanbul’s new Bosphorus Bridge presented the design and discussed the current specifications for long span suspension bridges. In addition, Thomas Lavigne, a partner in Lavigne Cheron Architects, presented his design for the new Jacques Chaban-Delmas lift bridge in Bordeaux, France. The projects are illustrated below.

The Third Bosphorus Bridge (left) and the Jacques Chaban-Delmas lift bridge (right). Photo Credit: Today’s Zaman and the American Society for Civil Engineering.

The conference also included many other speakers from around the world. The topics discussed include: Cable Supported Bridges; Bridge Rehabilitation; Seismic Analysis and Design; Bridge Monitoring; and Bridge History and Aesthetics.

Innovation in Bridge Rehabilitation

Corrosion of reinforcing, concrete degradation and concrete spalling are the three main concerns when dealing with concrete bridges. Traditional technologies employ a host of testing machines, causing the process to be quite inefficient; typically only 1000 sq. ft. of bridge deck can be inspected within one hour. Not only does this inefficiency increase the total cost of the project, but it creates traffic congestion and puts the worker’s lives at risk.

Researchers from Rutgers University have now developed a fully autonomous robotic non-destructive-evaluation platform. This product is an ‘all-in-one’ bridge inspection tool, and has the potential to drastically change the face of the industry.

The new product comes equipped with four resistivity probes, two surface imaging cameras, a laser scanner,and a GPS tracking system. This allows the robot to conduct all necessary testing, including: impact echo; ground penetrating radar; ultrasonic surface waves; and electrical resistivity testing. Furthermore, it is designed to move laterally and to turn at zero radius along a pre-set inspection path.

This product is able to inspect 4000 sq. ft. of bridge deck per hour (four times faster than traditional techniques). It also requires fewer workers on site, providing a higher level of project safety and efficiency. In addition, real-time data analysis is undertaken in a nearby van, allowing engineers to quickly address any concerns that arise.

Rapid Replacement of US 6 Keg Creek bridge

In an effort to reduce traffic congestion and fatalities during bridge construction, the US Congress approved the formation of the Strategic Highway Research Program (SHRP) in 2005 (Transportation Research Board). The SHRP has since developed an aptly named Accelerated Bridge Construction (ABC) process, which makes use of pre-fabricated modular construction.

The US 6 Keg Creek Bridge replacement in Iowa took place in 2011 and was a pilot project for the new system. This project would typically take six months to complete. However using ABC, the replacement took only two weeks. The fourteen day bridge assembly was made possible by the use of an on-site fabrication plant. However, this could not be done in densely populated areas. A time lapse of the bridge replacement is presented below.

The old bridge was demolished in just one day, using what Bala Sivakumar of HNTB Architects refers to as a “chop and drop” system. The cost of the replacement totalled $231 per sq. ft..

To connect the ‘lego’ pieces, joints were filled with ultra high performance concrete (UHPC). This created full moment connections, emulating a typical cast-in-place construction. The use of UHPC also allowed the six inches of overlapping reinforcing steel at joints to fully develop. However some problems did arise when applying the UHPC to the old concrete. This was resolved by installing post-tensioned rods which created compression within the joints.

Further Advancement

The new concepts and ideas discussed at the conference show how advanced the industry has become. However, there are still many aspects of bridge engineering that require improvement and optimization. As the industry grows, new research will continue to bring forth ideas that revolutionize construction practices. It is therefore imperative that conferences continue to occur, providing a platform for researchers to both share and inspire.

A Revolution in Bridge Repair

Today’s infrastructure is in disrepair, particularly our bridges. The issue, discussed in my previous post entitled The Age of Disrepair, has become a hot topic for discussion. As a result, research is being conducted across North America to develop new systems to find economical and environmentally friendly solutions.

Hannah Loring is a Civil Engineering graduate student at the University of Maine. Her research, under Professor Bill Davids, is focused on repairing the countries ageing bridge infrastructure. One of the major concerns with older bridges is weight capacity, as they were originally designed to withstand smaller, less frequent truck loads.

A proposed solution is posting weight limits on the bridges.  This will however cause traffic congestion. Alternatively, researchers at the University of Maine are developing a new product called a ‘polymer reinforced flexural retrofit system’.  This system uses strips of carbon and glass composites which are installed to the undersides of bridge decks using adhesive and concrete screws. The system increases the flexural capacity and lifespan of the bridge (Bangor News Report).

This product has the potential to revolutionize the way bridges are retrofitted. Professor Bill Davids suggests, “We’re giving a low-cost alternative for the short term that would increase the strength and durability of the bridge, prevent it from having weight [limits] posted, and allow the bridge to remain safe”. A typical deck replacement for a flat-slab bridge costs over $120,000. Using the composite strips, this can be reduced down to about $70,000. In addition, concrete beams reinforced with the polymer strips exhibit an increase in load carrying capacity from 15,000 lbs to 21,000 lbs (Bangor News Report). This research was presented at a recent press conference.

Press Conference Video

“Band-Aids” Aren’t Always The Right Solution

In some cases a full replacement of the bridge is required. Acrow Bridge, a company based out of the United States, specializes in prefabricated modular steel bridge solutions for permanent, temporary and emergency use. Acrow’s website claims that, “Through the simple addition of prefabricated modular steel bridge components, Acrow bridges are easily customized to the desired length, width and strength, allowing for diverse applications and uses”.

Acrow’s Temporary Bridge Being Used Adjacent to the Construction of a New Bridge. Photo Credit: Acrow Bridge

Acrow prefabricates the temporary bridge off-site, allowing for a quick assembly and minimal traffic disturbance. In addition, each section of these bridges can be re-used for different projects. Not only is this environmentally friendly, but it drastically reduces the overall cost. The product has been a huge success thus far. Bill Killeen, CEO of Acrow, said, “Consequently, more and more customers are expanding their inventory of modular steel bridges to deal with both emergency and scheduled repair work”.

There is no perfect solution for deteriorating bridges. However, with each passing day the process for repairing our bridges is being refined. If cities continue to take an active role in repairing bridge infrastructure using these technologies, bridge collapses may become a thing of the past.