Bridge – Rami Mansour

January 6, 2014

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

September 4, 2013February 25, 2018

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 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.

August 15, 2013February 25, 2018

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.

August 12, 2013February 21, 2018

Electrified Concrete: Creating Smart Cities

Lightning Hitting San Fransisco’s Bay Bridge. Photo Credit: Daily Mail

The concept of electrified concrete is not new. In 1980, W. Hymer wrote a research paper outlining the advantages of allowing current to flow through concrete. These included: protecting against lightning, eliminating static electricity, environmental healing and radio frequency interference (Concrete Construction). Despite this, little research was done to develop the concept.

Until now.

Researchers at the National Research Council of Canada (NRC) have begun developing a concrete which allows electricity to flow freely through it. This “smart concrete” can be used to prevent ice from forming, detect micro-cracks, and create cyber secure buildings. The concrete is mixed using conductive aggregates, which allow current to flow freely through the concrete (Txchnologist). However, this technology is expensive, and would only be implemented on critical sections of road and for bridge decks. In these cases, the cost of implementing the system is overshadowed by the amount cities spend on repairs.

Electrified Concrete Could Create “Smart Bridges”. Photo Credit: Cement.org

According to NRC’s Rick Zaporzan, “With a few tweaks, it can be used for developing a crack-detection system if it’s hooked up to proper sensors that can monitor and interpret that data”. In addition, the concrete could be used to block electromagnetic signals from entering or leaving, creating a cyber secure building. Rick Zaporzan claims that, “The concrete can also be used to protect extremely sensitive medical equipment, and that’s a huge application” (Txchnologist).

Implementing “Smart Roads”

By allowing electricity to flow through concrete roads, vehicles will be able to “recharge” their batteries while driving. Researchers at Japan’s Toyohashi University of Technology have created a process, wherein current sent through concrete decks is able to power objects on the surface (so far they have used the electricity to light an incandescent bulb). Although the technology is in the early stages of development, it could be used to power electric cars, eliminating the need to pull over and recharge (Engadget).

In addition, the Korea Advanced Institute of Science and Technology (KAIST) has developed a 24km strip of road which is able to supply specially made buses with power. Metal plates embedded within the road surface create electromagnetic waves, which provide electricity to the batteries built into each bus. This system eliminates the need for overhead wires, and allows buses to use significantly smaller batteries (CTV News).

The concept is explained in this short video:

Wall Street Journal Video

The possibilities for this product are seemingly endless. As cities begin to invest in smart infrastructure, more ideas will form, creating a much different world. Until then, however, it will remain a popular research topic for institutes around the globe.

August 1, 2013

The Age of Disrepair: What Do We Do With All These Bridges?

The issue of ageing infrastructure has become a serious concern in countries throughout the world. Bridges built in the past century have begun to crumble causing serious injuries, and in some cases death. In 2007, a bridge in Minnesota collapsed, killing 13 and injuring 145 people (I-35W Bridge Collapse) .Below is a video of the bridges collapse:

As a result, an investigation was conducted by the Federal Government of the United States to determine the cause of the collapse. In addition, the National Transit Safety Board was created to help improve the state of infrastructure and prevent future collapses. However, it seems that this issue has not been eradicated. During a speech in Galesburg, Illinois, President Obama stated, “We’ve got more than 100,000 bridges that are old enough to qualify for Medicare” (The Hill Report). According to a report released by Transportation for America, “11% of all bridges in the US are structurally deficient”. Considering that Americans make 260 million trips across bridges each day, this is a major issue (T4 America Report).

North of the border, Canadians are facing similar problems. A report released by Statistics Canada in 2007 stated that, “The average age of bridges went from 21.3 years in 1985 to 24.5 years in 2007, an increase of 3.2 years” (StatsCan Report). The province of Ontario has the third oldest bridge infrastructure in Canada (after Quebec and Nova Scotia) and its ailing bridge infrastructure has received a high degree of media attention. In Toronto, the capital of Ontario, the Gardiner Expressway has been identified as in need of serious repairs. The Gardiner is a major artery in Toronto’s downtown core, and a number of plans have been proposed to help rehabilitate it’s ageing bridges. However, the cost is quite steep. A current estimate puts the cost of repairing the bridge at $505 million (Globe and Mail Report).

Delamination on Gardiner Bridge Piers. Photo Credit: CBC News

It is well known that repairing older bridges drastically reduce maintenance costs. As a result, many engineers are starting to develop creative solutions to help restore these bridges. Innovation, unfortunately, comes with a price tag. As cities face more funding cuts, engineers are forced to use cheaper, less effective techniques to restore bridges. Professor Paul Gauvreau of the University of Toronto states, “When engineers are repeatedly requested to implement yesterday’s solutions – that is, not to innovate – engineering becomes a mere commodity that can be bought and sold at the lowest price” (Globe and Mail Report). As is often the case, these low-cost repairs are not very effective, and can lead to higher repair bills in the future.

A number of solutions have been proposed in the last few years that could potentially save cities millions of dollars on their repair bills. Some of these solutions include increasing the frequency of inspections, providing better drainage to current bridge decks, using domes to protect the bridge from rain and snow, and installing steel mesh beneath the bridges to catch any falling concrete (National Post Report).

Inspection of the Underside of a Bridge Deck in Missouri. Photo Credit: Missouri Department of Transportation

These solutions, however, are not always practical. More research needs to be done to find cost-effective repair techniques. Researchers all across the world are investing time and funding to help develop better, more efficient procedures for rehabilitating old bridges. As this research progresses, it will be interesting to see which solutions are adopted by the industry. In the meantime, cities will continue to pursue a ‘band-aid’ response to bridge deficiencies, leading to a higher potential for future accidents.