by ModyCity, Monday, 14 March 2022 (2 months ago)


America’s bridges are struggling. More than a third of the nation’s bridges are in need of repair and over 43,000 are in poor condition and classified as structurally deficient. A structurally deficient bridge is one that requires significant maintenance to remain in service. It is often posted with weight limits, but is considered safe to use. Each day, about 167 million trips are taken in the US across structurally deficient bridges.

The state of bridges in the US is not good and we’re losing the battle, if you will. America used to have the best roads, bridges and airports on earth and now, our infrastructure is ranked 13th in the world. Hours ahead of President Biden scheduled visit to Pittsburgh in January 2022. to discuss infrastructure, one of the city’s more than 440 bridges collapsed. Ten people were injured, including first responders. I think what we found is that we deferred maintenance for a long time and then all of a sudden, we’re at the point where, oh, we have this big backlog of maintenance that we have and we don’t really have the funding to catch up at this point.

Another bridge collapsed in Washington State in 2013 and in Minneapolis in 2007.And while most of the country’s structures were designed for a service life of about 50 years, the average age of bridges in the US is 44 years. Older bridges with fewer lanes and restricted access can add to congestion impacting commerce and the response time of emergency services. Because we are working on the busiest bridge in the world we’re over the Hudson River 200 feet above the water at the roadway level. The towers are 600 feet above the water. It proposes a tremendous amount of difficulty.

But innovations in bridge building, new building materials, as well as additional funding is showing signs of some modest improvement for the nation’s bridge inventory. In January 2022, President Biden announced his administration would distribute $27 billion over the next five years to fix or rebuild thousands of the nation’s bridges. The current estimate to repair all bridges in the US is $125 billion. So why are so many of the nation’s bridges in a state of disrepair and what steps are being taken to fix them?

Building Bridges Is Costly.

The US had more than 618,000 bridges in 2020, almost 44% were in good condition, 50.9% were in fair condition and 5.2% were in poor condition. Those bridges are also facing a midlife crisis. As of 2022 to 42% of bridges in the US are at least 50 years old, an increase from 39% in 2016. More than 10% of the country’s highway bridges are 80 years or older.

In the 1950s, 1960s, we built a lot of roads and highways and bridges in the United States. Most of them were designed for traffic loads that were 30 years into the future. So that would have taken us capacity wise to like the 1980s or 1990s. The population in this country has continued to grow, and commercial traffic has continued to grow. So we’ve put increasing wear and tear on the bridges in this country.

California home to more than 25,000 bridges that handled 673 million crossings each day has about 1,500 structurally deficient bridges. The 8.4 mile long San Francisco Oakland Bay Bridge opened to the public in 1936 at a cost of $77 million. But in 1989, an earthquake hit the Bay Area, causing a section of the structure to collapse, killing one person. Another 42 people were killed when a one mile section of the nearby Cypress viaduct in Oakland also collapsed. The bridge was designed of course in the 1930s when our understanding of earthquakes and our understanding of how steel and concrete react to those types of forces was not as advanced as it was come 60s, the 80s and 2000.

The Bay Bridge was quickly repaired, but a decision was later taken to rebuild the entire eastern span. One of the very first designs that was proposed for the Bay Bridge was a very plain vanilla quote unquote, type of structure and the Bay Area objected to that uninspired aesthetic, let me put it that way. So there was a halt to the design process and a rethinking and we ended up with of course a more striking type of structure. But even that had its problems because the redesign envisioned a 700 foot tower that was going to lean on a 15 degree angle. And that led to extremely complicated technical issues and expensive issues. Skyrocketing costs and design issues plagued the project.

According to Ibbs the revised project came in over budget and had to be redesigned yet again, safety issues were another factor. Prior to the opening, a survey found 32 of the more than 2,300 steel rods used to withstand earthquakes were damaged. All told it took almost two decades to really rebuild the project and somewhere north of $5 billion to rebuild this really important structure that was crucial to the Bay Area commerce and Bay Area travel. The new section the Bay bridge opened in 2013 five times over budget, and six years behind schedule, at a cost of $6.4 billion.

Privately Owned A Bridged

While most bridges in the US are owned by either a local or state agency, about 2,200 are privately owned. Linking Detroit Michigan with Windsor, Canada, the privately owned Ambassador Bridge opened in 1929. The bridge accounts for about a quarter of goods traded between the two countries. Canada is one of the US’s largest trading partners with more than $600 billion in goods traded in 2019. But congestion and concerns related to pollution, as well as bottlenecks due to increase security have led stakeholders to call for a new river crossing.

We go back 100 years when the Ambassador was first built, the amount of traffic going across there was quite small compared to today. I don’t think anybody at that time could predict the integration of the two countries in their economies. In 2020, there were over 2.2 million truck crossings annually on the Ambassador Bridge.

That seems to be a classical problem with many, many bridges in the US not just this private one is you build them today to last 50 years, you build them based on a traffic count of today and with some projection. But then people grow. People travel across and maybe migrate from one state to the other, traffic volume increased significantly. Now there is not enough lanes that are always heavier traffic than design loads. And that would create some of the deteriorations that we see on bridges.

In 2018, construction began on the Gordie Howe International Bridge located just a few miles away. So you probably see there a lot of the steel and they’re going to be pouring concrete all around this location here. One of the reasons why the government of Canada went down this path of building this new bridge is to ensure that there is always this connection, and that there’s a redundancy in the area to make sure that even if the Ambassador Bridge, for instance, had to close to do renovations to enhance his life, we don’t want to lose that capability to put goods back and forth between the two countries.

In addition to the cost building a bridge on an international border has its own set of challenges, including coordinating with local, state and federal authorities as well as Border Services in two countries. So how to you build a bridge over water when the next support you have for it is 1000 feet away, half a mile away. It’s quite the engineering feat and the construction feat that we’re going through to actually construct this infrastructure project, it is something to see. Construction of the bridge is being done using a balanced cantilever method.

This involves building to 720 foot towers on both sides of the Detroit River and then building the bridge deck piece by piece outwards until the two cantilevers meet in the middle, costing an estimated $4.5 billion the Gordie Howe International Bridge. A six lane 1.5 mile long cable stay design is set to open in 2024.

The George Washington Bridge.

The bridges designed for a service life of 125 years. While 77% of all US bridges are located on rural highways, 73% of all bridge traffic takes place on urban bridges. The George Washington Bridge is one of the world’s busiest bridges. In its first full year of operations in 1932, more than 5.5 million vehicles crossed between New York and New Jersey.

By 2019 the bridge was handling more than 122 million vehicles annually. Those additional cars and trucks have led to gridlock for commuters and truckers making the bridge the top ranked US truck bottleneck, according to 2019 data. Congestion on the nation’s highways cost the trucking industry more than $74 billion in 2019, the equivalent of over 425,000 truck drivers sitting idle for an entire year. The relentless traffic has also brought with a decades of wear and tear on the 90 year old bridge whose to 604 foot towers, along with their suspended structures contain more than 43,000 tons of steel.

This is probably one of the most vital links in the I-95 corridor along the entire highway system. We pretty much connect everything from down south to Florida all the way up through New England. If you can’t cross this bridge, New England gets cut off. In the mid 2010s.

The bridges owner the Port Authority of New York and New Jersey kicked off a decade’s long construction project in a bid to rehabilitate the structure. One key component was to replace all the bridges 592 vertical suspender ropes, which have been in place since it opened in 1931. Here you have the cable bands that go around the main cable and support the suspender ropes that go down to the bridge structure below.

So we would remove the existing suspended rope, remove the cable band, take that off site, clean it up, paint it, bring it back and reinstall it, and then reinstall the new suspended rope. Other projects include the installation of a dehumidification system, replacement of the bridge’s sidewalks and the replacement of roadways leading to the bridges bus station. The project is expected to cost about $1.9 billion.

But are US bridges safe for travel? Yes, according to one analyst. The role of evaluating bridge deficiencies lies with the Federal Highway Administration that provides guidelines for bridge inspections in States Department of Transportation units, who are usually the arbitrator of whether an overpass is safe for operation. In general, bridge inspections occur every 12 to 24 months. From an industry perspective, we want to find urgency.

And one way to find urgency is to say that, look, we have all these poor bridges, this is a dire situation we need to but really from the engineering and safety side of it that does not necessarily match up with people are in danger right now. Because our processes are working. Our safety factors are working, our inspection is working.

Our mitigation is working once we find that there are issues with bridges. And while the backlog of bridges in need of repair or replacement is massive and the cost daunting innovations in bridge building, along with new materials is allowing engineers to keep structures in service for even longer. You’re seeing advances in terms of new materials of construction, new concrete, new steel, new asphalt, you’re seeing advances in terms of the way in which we build bridges. There are now programs that emphasize modularization and pre-fabrication of components of bridges so that we can get in and get out real quick with renovation of bridges.

The bridge was built in 1931 it’s been here for 90 years it is still functional and in a state of good repair. And the work we’re doing is to ensure that it lasts for another century to come.


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