The state of our country’s infrastructure has been a hot topic lately, and for good reason. Truck traffic is getting heavier, bridges and structures are aging, and it’s not unheard of to learn of a structural failure or collapse.
Do you know what condition your infrastructure is in? Are you aware of what kind of truck traffic it can support, or if there are any measures that can be taken to increase its useful lifespan?
State and Federal Requirements
Every qualified bridge or culvert owned by Local Public Agencies (LPAs), such as counties or cities in the tri-state area, must meet state and federal requirements for inspections, maintenance, load ratings, and load postings. It is up to each bridge or culvert owner to stay up-to-date on their jurisdiction’s requirements, generally so they can continue receiving funding for new transportation projects.
Inspection Plans by a Professional
Bridge inspectors and structural engineers can help you determine a suitable inspection plan. During inspections, maintenance measures can be identified to prolong the life of your bridge or culvert, such as keeping channels free of debris, cleaning or replacing bridge joints, concrete repair, scour protection, and many other options. In between inspections, proper maintenance measures should be followed to allow the public to continue to use an asset for as long as safely possible. Developing issues can be monitored to determine your structure’s remaining useful life, and to identify funding options for repair or replacement to meet current and future needs.
Another crucial piece of information that should be a part of each inspection file is a structure’s load carrying capability. Each jurisdiction will dictate which types and weights of vehicles a structure should legally be able to support. When a structure can no longer support (or was not designed to support) a particular legal truck load, proper signage must be posted for the bridge or culvert indicating its safe load carrying capacity. Failure to post this could result in damage to the structure from overloading, possibly decreasing its life span or even resulting in a collapse.
To determine the safe load carrying capacity, calculations are performed to analyze structural members such as girders, decking, truss members, or floorbeams to verify their strength and compare that to the loads imposed by truck traffic. This is known as a load rating.
New! Requirements for SHVs
Recently, the Iowa DOT updated its load rating requirements to include more rating vehicles, called the Special Haul Vehicles (SHVs). The deadline to update applicable load ratings to include SHVs is Dec. 31, 2020, so consideration should be given now to budget for rating updates to stay in compliance.
As a bridge or culvert owner, you may also be contacted by individuals wishing to cross your structures with special permit vehicles. A special load rating must be completed to verify your structure can support unique permit loads. If a standard load rating has been calculated for the structure already, it will be that much easier and faster to update it for a special permit request. The costs to run a permit analysis often can be passed on to the permit applicant.
Having your infrastructure properly inspected, maintained, and being informed of its safe load carrying capacity is paramount to the safety of the traveling public. IIW has a team of bridge inspectors and structural engineers that can help ensure your structures are meeting your jurisdiction’s requirements. This is important so you may continue to receive funding for future transportation projects to keep residents safe and traffic flowing.
Do you need help managing your bridge program? Contact us today.
Courtney Wand, PE is a structural engineer in IIW’s Transportation Department. She has assisted several counties and municipalities in the tri-state area with their bridge programs, including performing load rating calculations on steel, concrete, pre-stressed concrete, timber, and truss type bridges.