A recent analysis of federal bridge data confirmed the ASCE (American Society of Civil Engineers) report card bridge grade of C+ with an overall Infrastructure grade of D+.
The Importance of Infrastructure for Economic Growth, Jobs, Access to Markets and Services globally is of an importance so far reaching and often ignored … From air and marine transport links, to good roads, bridges, telecommunications and energy generation, all are needed for provision of reliable services, and to enable local businesses to grow and expand.
Bridges are a key component of all nations infrastructure. Poor bridges mean goods are delayed to both market and port. Billions are wasted in lost productivity with commuters stranded in traffic instead of being productive at work. A bridge collapse can result in terrible loss of life as well as disruption of traffic and loss to the economy of any nation.
Keeping bridges safe as they age requires doing away with the current manual, subjective inspections and adopting modern technologies and robotics to provide more quantitative data. Quantitative data allows bridge maintenance and asset owners better manage and budget for maintenance and repairs.
The highly publicized collapse of the I-35W bridge over the Mississippi River took place on Aug. 1, 2007. It resulted in 13 deaths and 145 injuries.
In addition, it caused significant collateral damage and economic costs. The bridge was Minnesota’s third busiest, carrying 140,000 vehicles daily.
A design flaw was found to be the likely cause of the collapse. Experts believe a too-thin gusset plate ripped along a line of rivets because additional weight on the bridge at the time of the collapse put significant stress on this weak component of the design.
Previous inspections over many years had rated this span as one of the most vulnerable in the United States. It was inspected annually except for the year of the collapse because construction was taking place on the bridge. In their final report, officials noted that inadequate inspections were a contributing factor to this tragedy.
Current Bridge Inspections
There are approximately 650,000 bridges in the National Bridge Inventory NBI. These only include bridges over 20feet. There are tens of thousands of smaller bridges not represented in the NBI.
These bridges are owned and maintained by countless state, local, federal and other entities. Most of these agencies are consistently strapped for cash and have limited resources available to conduct adequate in-depth inspections.
The federal guidelines require inspections of NBI bridges every 2 years, however each state and in many cases DOT (Department of Transportation) district may of may not conduct these inspections in a timely manner based on their budgets and availability of funds.
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The National Bridge Inspection Standards (NBIS) are regulations that were first established in 1971 to set national baseline requirements at a federal level regarding bridge inspection frequency, inspector qualifications, report formats, and inspection and rating procedures.
The NBIS (National Bridge Inventory System) can be found in the Code of Federal Regulations, Part 65, Title 23, Subpart C which is on the Bridge Technology site located on the FHWA (Federal Highways)
The NBIS set minimum, nationwide requirements. States and other owner agencies can and do establish additional or more stringent requirements
There are currently various types of bridge inspections as outlined by the FHWA in order for the states to have a guideline to follow based on national experience. Some of these include:
This is the first baseline inspection when construction is finished and a bridge is first open to the public. Baseline structural condition information is collected to compare against future inspections.
It typically includes mostly manual and subjective techniques. Future initial inspections should require more quantitative data and not just visual. Confirming rebar placement, cover thickness of the deck and proper grouting of post tension tendons would be a few areas where technology can help insure that the contractor did not cut corners and the bridge is at its highest level of safety for public use.
The routine inspection frequency should not exceed 24 months unless FHWA approval is given for a 48-month routine cycle. The adjusted date should not extend more than 30 days beyond the scheduled inspection date, and subsequent inspections should adhere to the previously established interval. The routine inspection is used to determine the physical and functional condition of the bridge from the last inspection.
A special inspection is defined in this regulation as “an inspection scheduled at the discretion of the bridge owner, used to monitor a particular known or suspected deficiency.”
In Depth Inspection
A close-up inspection of one or more parts of the bridge above or below the water surface. This type of inspection is done to identify any issues that are not easy to detect using more routine inspection procedures. This is usually a very hands-on process. This is an inspection that is ordered at the discretion of the bridge owner and is used to detect or monitor a particular known or suspected deficiency. Once again a “hands on” inspection should include the best technology available to determine the seriousness of any abnormality.
There are other types of inspections mentioned in the NBI but ultimately the safety of any structure is in the hands of those that are inspecting that structure. There are many variables that can affect the quality of that inspector outside of the fact that most of the current inspection methods are still manual and have not been updated in 50 years or more. But just think about it. If inspections go to the lowest qualified bidder is there a possibility of that asset manager cutting corners to save money. We hope not, but by upgrading to modern inspections and robotics that record the entire structure being inspected this is much less likely.
It is interesting to note that the contractor managing the FIU bridge that collapsed in Florida was having financial difficulties and although that is not a guarantee that corners will be cut it is still hard to believe that a contractor was working on a bridge tightening a main cable over live traffic.
Following standard protocols and proper procedures to have the road closed and traffic stopped would certainly have been more costly, but could have saved lives.
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Problems With Current Bridge Inspections
The bridge maintenance and inspection process in the US is a complicated one. From managing budgets to having to handling multiple maintenance issues, new construction and updating failing structures, the DOT has their hands full. The methods used to inspect the infrastructure has not changed in 50 years. As the bridges age and continue to deteriorate not updating these methods pose a risk to the traveling public and a nations economic viability.
Lane Closures and Traffic Disruption
Because all of the bridges that the FHWA maintains are also public roadways, traffic must be considered when planning a bridge inspection.
Depending on the location and design of the bridge, traffic might even have to be rerouted or stopped in order to perform the inspection properly. This can cause delays, complaints, or potential traffic hazards. Traffic control often also necessitates the involvement of local law enforcement.
Dangers to Personnel
Inspecting bridges can be quite dangerous (Minnesota’s Department of Transportation, Bridge Inspector’s Reference Manual, 2.2.1).
In addition to inherent dangers that can include being suspended from significant heights, moving around and over potentially unstable structures, and working in and around water, personnel are regularly exposed to outdoor elements, inclement weather, traffic, and more. Significant training is required to ensure safe working conditions for bridge inspectors to minimize risks. Updating inspection processes can minimize this risk. Stop climbing cables or lowering inspectors into shafts and utilizing technology is one way to minimize this risk.
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Varying regulations affect bridge inspection procedures. Bridge inspection must be performed in ways that will not disturb endangered and protected fowl migration and nesting periods.
Inspectors must also keep current on other protective environmental measures, such as for water or plant life, to avoid compromising or damaging protected flora and fauna during their inspection efforts.
Regulations also stipulate other aspects of bridge inspection including managing personnel qualifications, controlling scheduling procedures, requiring thorough record keeping, and more. Following these procedures and ensuring that all state records are kept up to date can help asset managers maintain structure safety.
Bridge Collapse- Morandi Bridge Collapse
The Morandi bridge tragedy killed 43 and left 600 homeless – but also dealt a hammer blow to Italy’s engineering legacy.
The bridge is a main road in and out of Genoa, linking it to the A10 motorway and the road to France.
According to one study state DOT’s need to utilize more human resources for bridge inspections. From the survey some states do not have enough engineers and inspectors in their maintenance departments causing delays in inspections.
The problem with this theory is that it is not a budgetary issue but a matter of a diminishing workforce. Graduating engineers and technicians do not want to spend their careers working in an antiquated industry that does not adopt new and modern technologies.
As odd as it sounds the bridge inspection industry is still mostly manual and visual. In the 21st century that would leave anyone out of a job permanently if they were fired from a bridge inspector role with no skills to move into other industries, something graduating engineers are keenly attuned to today.
The speed adoption of modern methods, robotics and software needs to be more efficiently integrated into the field of bridge inspections. Utilizing technology, fewer engineers are required to conduct the same amount or more inspections than ever before in the same time period.
With the diminishing availability of qualified inspectors, the consequences are not only a matter of manpower but economic security and literally life and death.
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How To Perform A Better Bridge Inspection
A better bridge inspection must first start with changing the way we conduct inspections, gathering, recording and storing information. It must start both at the Federal level as well at the state and county levels.
DOT maintenance offices need to be encouraged to find and adopt better inspection solutions. These solutions exist today and are being used in the field today.
From Drones to robotic inspection services like those offered by Infrastructure Preservation Corporation.
Our infrastructure is ageing and business as usual needs to change. We are in an amazing time of advancing technologies and robotics, unlimited cloud storage and artificial intelligence and yet we still drag a chain across a portion of a bridge deck, still wedge open load bearing cable and still put inspectors at risk and lower them into dark, dangerous bridge columns to look for issues and corrosion.
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Did you know: Repairing all U.S. bridges would cost about $140 billion, three times what the federal government receives in taxes annually for road, mass-transit and bridge projects, according to the engineering society.
We can perform faster, smarter bridge inspections safer and at a lower cost. We can re-train experienced inspectors to get the value of their experience along with more quantitative data at a lower price than ever before.
Regarding budgets..This is the United States of America. One of the wealthiest countries with one the largest economy in the world. We may not have the money to make all repairs and replacements in the budgets in every state today, at this moment, but we certainly do have the money to pay for proper inspections to locate the most severe issues, if allocated funds were directed properly and inspections updated and conducted properly. How much more expensive is it to wait for a bridge to collapse.
How much better do you think you could budget for repairs…How many more repairs do you think you could make with the same taxpayer dollar if we utilized technology and had more quantitative data to work with?
IPC’s BridgeScan® costs the same price to scan an entire bridge deck that a manual visual inspection costs. The difference is that IPC scans the entire bridge deck and approach roadway. It can tell you cover thickness, rebar placement, delamination, debonding, compactness of gravel and soil, find voids, water intrusion and more.
This device and the subsequent report can also provide quantity of materials required for repair and budgets per bridge to make those repairs.
How much further do you think you can stretch that taxpayer dollar knowing what needs to be fixed, where and how severe that issue actually is on each of your structures. The ability to look at deterioration progression over time during subsequent inspections…
How do you perform a better bridge inspection??? It starts by having the desire to.
The cost of not doing so is much greater… to the nations economy and public safety.
Management and allocation of resources and budgets may be the immediate cry, but their is certainly enough money to conduct proper inspections if to was a priority.
In fact it may not be a matter of spending more money at all, but in conducting more modern inspections that cost less, produce more data and enable a much more efficient budgeting of maintenance and repairs.
It is certainly sexier to build bridges than conduct maintenance and there are certainly bridges being built all over the USA from the $1.2 billion Gerold Desmond bridge in California to the newly finished Tapanzee.
Maintenance and repairs certainly wont win any votes but why not collect the critical data that can help the department of transportation properly budget for and conduct the necessary repairs.
One of the questions that so frequently arises is how do we quickly without years of government bureaucracy move from manual visual inspections to utilizing modern technologies and inspection methods that can cut the inspection to a fraction of the cost and supply more quantitative data for the asset owners to make more efficient budgetary decisions for repairs and maintenance with a higher degree of safety?
The answer is by utilizing technology today that has been proven in the field and where multiple inspectors can realize consistent results and that can replace current methods at the whim of the project manager, maintenance supervisor or department of transportation lead. Every department of Transportation contract allows the DOT to pull any part of a contract from any asset manager or vendor if it is in the public’s interest. As far as I know public safety is in the public interest.
Bridge Collapse -Cần Thơ Bridge
There are certainly headwinds to the adoption of anything new. Even proven technology that exceed the safety and reporting guidelines.
From “man hours” billed by the engineering firms to the DOT that they may be giving with more efficient inspections. To those that are just reluctant to change as well as long term relationship that may be disrupted, updating and industry safely is certainly no easy task.
Then again if the asset management and engineering firms took a closer look, what they are giving up in inspection revenues they will gain by a large multiple in design, repair and maintenance work for identified problems that need repair. They can more efficiently manage their contracts, scheduling, budgets and field crews with more data.
How can the DOT quickly adopt these inspections?
So long as they meet current requirements they can adopt them today. Current inspections may say that you need to inspect a cable from 6″ away. Today’s robotics can climb the cable and not only meet the FHWA and AASHTO requirements but exceed them by a long shot. It can inspect 360 degrees from 6″ away with high def video and stills of issues showing the size and position of problems that can be compared against future inspections to quantify deterioration progression over time.
What else can adoption of new and modern technology do for us?
Modern technology will minimize lane closures.
This in itself is a huge savings to the Department of Transportation, the traveling public and the economy overall.
Modern technology will reduce budgets.
Utilizing non destructive testing and robotic engineering will minimize lane closures and heavy equipment rentals on structures. It is more efficient and less costly and safer than current methods.
Modern technology will be safer for the public
Without obstructions on the road, there will be fewer accidents. Keeping the structures safe will help ensure public safety.
Modern technology will be safer for the inspector
No more repelling down large structures to inspect or lowering an inspector into a bridge column. Fewer inspectors on foot on the bridge with safer methods will ensure safer infrastructure inspections.
Modern technology will save billions in infrastructure costs.
Modern technology and robotics that are able to locate early stage deterioration will help asset owners make better maintenance and repair decisions. Insuring fixes prior to them becoming a concern and helping to extend the service life of critical infrastructures worldwide. Bridge maintenance is much less costly than building a new bridge.
Modern technology will allow for more efficient budgeting for maintenance and repairs.
By utilizing a much higher degree of of quantitative data and producing more advanced inspection reports the department of transportation can better allocate assets for repair.
Bridge Collapse -Florida
Just hours before a pedestrian bridge collapsed and killed six people at a Miami university, engineers confirmed that cracks in the concrete structure “increased in length daily,” according to meeting records released Monday by the Florida Department of Transportation.
Utilizing Modern Tech For Bridge Inspections
Bridge inspections have primarily been conducted the same way for 100 years. There have been very few upgrades to the way bridge inspections are conducted and major legislation seems to be only tendered after each major disaster.
The Silver Bridge was an eyebar-chain suspension bridge built in 1928 and named for the color of its aluminum paint.
The bridge carried U.S. Route 35 over the Ohio River, connecting Point Pleasant, West Virginia, and Gallipolis, Ohio.
On December 15, 1967, the Silver Bridge collapsed under the weight of rush-hour traffic, resulting in the deaths of 46 people. Two of the victims were never found.
The safety of the bridge network came into question in the late 1960s when, on December 15, 1967, the Silver Bridge spanning the Ohio River between West Virginia and Ohio collapsed during rush-hour traffic.
This catastrophic event resulted in 46 fatalities and a number of other injuries. This prompted national concern about bridge conditions and safety. Following this disastrous event, programs were established to ensure periodic safety inspection of bridges and provide mechanisms for funding of bridge replacement and rehabilitation needs.
The primary bridge programs include the National Bridge Inspection Program (NBIP) and the associated Highway Bridge Replacement and Rehabilitation Program (HBRRP).
Summary of major Bridge Inspection and Bridge Program Funding. Legislation and Noteworthy changes. https://www.fhwa.dot.gov/policy/2004cpr/chap15a.cfm
Summary of Major Bridge Inspection and Bridge Program funding Legislation and Noteworthy Changes
|Act and Date||Requirements|
|Federal Aid Highway Act of 1970 (P.L. 91-605)||Inventory requirement for all bridges on the Federal aid system.|
Establish minimum data collection requirement.
Establish minimum qualifications and inspector training programs
|Surface Transportation Assistance Act of 1978 (PL 95-599)||Provided $4.2 billioin for the HBRRP over 4 years|
Expanded inventory requirement to all bridges on public roads in excess of 6.1 meters.
Establish highway bridge rehabilitation and replacement program (extending funding to rehab) to replace Special Bridge Replacement Program
|Highway Improvement Act of 1982||Provided $7.1 billion fo rthe HBRRP over 4 years.|
|Surface Transportation and Uniform Relocation Assistance Act of 1987||Provided $8.2 Billion in HBRRP funding over 5yrs. |
Added requirements for underwater and fracture critical inspections.
Allowed increased inspection intervals for certain types of bridges.
|Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA)||Provided $16.1 billion for the HBRRP over 6 years. |
Mandated state implementation of bridge information management systems
Increased funding in HBRRP
|National Highway System Designation Act of 1995||Repealed mandate for management system implementation|
|Transportation Equity Act of the 21st Century||Provided $20.4 billion in HBRRP (Highway Bridge Replacement and Rehabilitation Program) funding over 6 years.|
As worldwide infrastructure continues to age, it is more important than ever to update inspections to incorporate modern technologies and robotics with advanced infrastructure reporting to provide the required data to help insure public safety and the safety of our infrastructure.
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Manual, Subjective Cable Stay Inspection. Lane closures and heavy equipment required on the bridge. More dangerous for the inspector and the public. Less data, more expensive.
A cable stay inspection may require an inspector be viewing the cable from 6″away. It does not require the inspector to be dangling from a rope or swinging in the wind on a bucket truck viewing 1 side of a cable stay.
Bridge Collapse -New York State
Schoharie Creek Thruway bridge collapse. A New York State Thruway bridge over the Schoharie Creek near Fort Hunter and the Mohawk River in New York State collapsed killing 10 people.
Better Bridge Inspections With Modern Technology and Robotics
Magnetic Flux Leakage “MFL” has been used to detect corrosion and pitting in steel structures. MFL is an electromagnetic non-destructive testing method that is proven
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Thank you Icons Of Infrastructure in helping to build awareness of the importance of updating current bridge inspection methods. With the state of current infrastructure and budgets
ABSTRACT: A non-destructive evaluation (NDE) of long steel bridge cables is required to avoid structural damage during an inspection . Therefore, a robotic cable monitoring