On October 13, 2026, the Ohio Department of Transportation (ODOT) closed the Barnhill Road bridge, County Road 68, over U.S. Route 250 in Midvale, Tuscarawas County. Several weeks earlier, a vehicle hauling heavy machinery had struck the bridge and damaged several beams, and ODOT had narrowed traffic to one lane controlled by temporary signals. During the monitoring and inspections that followed, inspectors found significant cracking in one of the damaged beams, and ODOT closed the bridge to all traffic as a precaution. U.S. 250, which is positioned below the bridge, stayed open, and ODOT is working on a permanent repair with no reopening date yet.

The process worked as intended, because inspectors found the crack and the bridge was closed before anything worse happened. Still, the damage found on October 13 was not the damage found on the day of the strike, and bridge strike statistics, which count impacts, rarely capture that difference.

Bridge strikes and hidden damage

Bridge strikes happen often. According to the NCHRP guide on preventing bridge and tunnel strikes, NHTSA, the federal agency that collects crash data, records more than 14,500 crashes involving bridges every year. State transportation departments see the same problem on their own structures, and in a national survey most of them reported between 2 and 30 strikes a year. The consequences can be serious, because FHWA, analyzing the data of the National Bridge Inventory, lists vehicle and vessel impacts among the most common causes of bridge failure.

The damage is not always visible, because it can be inside. In fact, a research report for the North Carolina DOT describes the assessment of impacted prestressed girders as particularly challenging, because of internal damage that is hard to detect. In a pooled fund study led by the Missouri DOT, researchers tested girders that had lost 3 and 6 of their 12 prestressing strands in controlled impacts, to measure how much strength remained. Research at the University of Pittsburgh found that impact damage rarely causes immediate collapse, but if left untreated it can accelerate deterioration, often through corrosion of the prestressing steel.

Some strikes are not even reported. Researchers at the University of Wisconsin–Milwaukee working on a new NCHRP study have pointed out that many strikes go unreported or undetected until the next scheduled inspection.

Between the strike and the closure

After a strike, the owner inspects the damage, decides whether the bridge can stay open and schedules follow-up inspections. In some cases the damaged beam continues to carry the weight of the vehicles passing the bridge, and a crack that starts at the impact zone can extend under repeated loading. In Midvale, it became significant enough to close the bridge within a few weeks.

Commenting on a strike on the County Road 87 bridge over I-65 in Calera, Alabama, Mohamed ElGawady, who studies impact-damaged girders, explained that after a strike engineers look for more cracking, sagging or deflection of the girders, shifted beams, and movement or damage at the supports. Apart from the cracks, every item on that list is a structural response that can be measured with sensors.

A DECK002-X displacement sensor under the struck beam could record its deflection at every crossing, and the same sensor under an undamaged beam would give the reference measurement, while tiltmeters at the supports record rotations and any movement of the bearings. If the damaged beam started to deflect more, or the adjacent beams started to carry more, the load would be redistributing because the damaged beam is losing stiffness.

Accelerometers such as the AXE-STD-LR-2 can also add a record of the impacts themselves, because a strike produces a short, high acceleration. Since the same structures tend to be struck again (unfortunately), measuring all hits is important for the general overview of a bridge. In New York State, which records about 200 strikes a year, a City College of New York study found that most strikes happen on a small number of bridges, and one bridge in Rye Brook was struck more than 100 times in ten years.

As a consequence, inspectors could visit the site on an on-demand basis rather than following a regular interval. With alarms set on the difference between the damaged beam and the others, the team responsible for the bridge receives a notification when something changes, and the next inspection can start that day.

The limit is that small cracks, or broken strands inside a prestressed girder, can reduce capacity long before they change the response under traffic. For this reason the data do not replace the follow-up inspections, but they help decide when the next one is needed.

Frequently Asked Questions

Can sensors detect a bridge strike?

Yes. An impact on the superstructure produces a short, high acceleration that stands out from traffic vibration, so accelerometers on the span record when it happened and how strong it was. This gives the owner a reason to inspect even when no driver or witness reports the strike.

Does every bridge strike require closing the bridge?

No. Many strikes cause minor or local damage, and owners decide after inspection whether to keep the bridge open, restrict traffic or close it, depending on the damage found and on how the damaged member is expected to behave under traffic.

How soon after a strike should sensors be installed?

As soon as the damage assessment is complete and the bridge stays open. The first days of data after the strike become the reference for the damaged beam, and any later change in its response is measured against that reference.