Inspectors Snoop Under Bridges to Check Conditions

An under bridge inspection unit, also known as a snooper truck, is an odd looking vehicle that causes many who see it to do a bit of a double take. On May 27, there were many spectators at Table Rock Lake in Branson, MO that did just that. While they were watching from the lake front, dam observatory and occasionally from idling boats, a four-man MoDOT crew was assisting the Army Corps of Engineers in the inspection of the dam.

The under bridge inspection unit on location in Branson that day is one of only three in the state. With so few units statewide, each truck and crew covers a large portion of Missouri and its bridges. All three crews are part of the Bridge Management Section of the Bridge Division.

The trucks and the crews that operate them are an invaluable asset when it comes to making sure the bridges of Missouri are safe for motorists. Every bridge in Missouri is inspected regularly for safety. If a disaster happens, a bridge must be inspected immediately before motorists will be allowed to drive on it for their safety.

In order for the crew to inspect under the bridge, the snooper truck can extend its arm allowing the operator to go off the side of the bridge. A counter weight on the truck prevents the unit from tipping over. The arm is then maneuvered into position underneath the bridge for inspection. The truck’s arm can lower itself and reach a total of 62 feet across the width of a bridge for the inspector to check for cracks, damage and deterioration.

If a crack is found, it is measured and evaluated to make sure it is not compromising the integrity of the bridge. Not all cracks are equal. While bridges will have cracks, the crew is looking for cracks in areas of stress, or cracks that show growth from a previous inspection. They also are testing the thickness of the steel in areas of section loss caused by rust to make sure it is still in good condition.

According to the bridge inspection crew, it is not uncommon to close up to two bridges a month in need of immediate repairs. The bridge deterioration can be caused by numerous things. It can be from the salt and abrasives added during winter to help keep ice off the bridges that cannot be reached to wash away, or simply from fatigue over time caused by heavy trucks passing over it.

In Missouri, there are more than 10,400 state bridges. A total of 208 bridges are considered “major” meaning they exceed 1,000 feet in length. Currently 47 of those major bridges are considered to be in poor condition while an additional 97 are only considered to be in fair condition. Overall a total of 6,598 bridges are in fair to poor condition.

Don’t Forget to Wash Behind Your…Bridges?

Starting at MoDOT I knew I had a lot to learn. Each day is a new lesson on how MoDOT works and what we do to provide a world-class transportation experience. While I am trying to take in all of this new information, one thing that I heard recently I didn’t expect. MoDOT washes bridges.

After making sure my coworkers were not pulling a fast one on the new guy I wanted to learn more about this process and why we do it. I reached out to Maintenance Liaison Engineer Michael Shea who was happy to help a new MoDOT employee learn about this maintenance procedure.

During the winter season salt is put on the roads to help melt the ice and provide safer driving conditions for Missourians. When the weather gets warmer it is common to wash your car so the salt and abrasives don’t start to cause erosion and rust.

In order to keep the bridges free from the same salt and abrasives that could lead to deterioration on your car, MoDOT washes Missouri bridges twice a year using flush trucks, sweepers, and other equipment. It doesn’t matter if the bridge is new or old, it will be washed before and after the winter season.

Washing the top surface of the bridge is only half the battle. Many bridges have expansions joints that can start to leak due to the forces of nature hitting them over time. These leaks can lead to salt and abrasives getting down underneath the bridge. Although it can be harder to get to and may require the use of scaffolding, washing underneath the bridge is just as important as the side you drive on in order to maintain a better bridge.

If you ever come across a maintenance crew blasting water on a bridge remember they are there helping keep that bridge healthy for you to drive on for years to come.    

Paging Dr. Bridges

Central Missouri motorists might see a tricked-out van similar to this driving on and around bridges.

It belongs to a company called Penetradar. They use ground-penetrating radar to evaluate pavement - as in this image from their website. It's also great for analyzing bridge decks.

Think of it as a giant CAT scan or MRI. Back in the day, doctors often operated with minimal information - maybe an X-ray and a list of symptoms. Surgery was measured in hours and recovery in weeks. Now before surgery, doctors and technicians gather information so they know what they'll face in the operating room. Some surgeries are down to minutes and often patients go home the same day.

MoDOT is planning to start some bridge work in the Columbia area soon, so the van is gathering data. That information will help identify issues within the bridge that need addressing before a single cut is made in the pavement.

That helps the repair contractor. They'll know what they are facing before they open the surface. Fewer surprises make for less stressful, more profitable work.

It helps MoDOT. Fewer surprises make for fewer last-minute (often expensive) fixes and keep work zone time to a minimum.

But most of all, it helps motorists. When a contractor knows what they'll face, they can "operate" and get out of drivers' way more quickly.

Now...this will only hurt a little bit...

Protecting Shoes...and Bridges

This blog was written by Travis Ellis of MoDOT's Northwest District office.

Everything is more expensive these days, and the need to prolong our items is becoming even more important. Many of you take the time to polish or "seal" your favorite, or most expensive pairs of shoes before the onset of winter. You do this to keep what is inside dry, and to make the shoes last longer, just like the Missouri Department of Transportation does with its bridges.


"We seal our bridges for the same reason folks seal their shoes," says District Maintenance and Traffic Engineer Marty Liles. "Whether you are weather-proofing a pair of shoes, or a bridge, it protects them from the elements and makes them last longer."

In the coming weeks, motorists can expect to see discolored bridge decks, extra work zones and crews around many of Missouri's bridges.

As the sealant is applied, it fills cracks, even those too small for most people to see. That keeps water from seeping into the pavement. When water does manage to get through pavement, it expands when it freezes, causing the crack to grow larger, sometimes creating potholes.

Bridges are selected for sealing, or re-sealing, based on a number of factors. All new bridges are sealed prior to their first winter. After a bridge has been sealed the first time, existing bridges are scheduled for re-sealing on a rotating basis.

"We are taxpayers too, and we want to preserve and prolong our roads and bridges in the most cost-effective means as possible," says District Engineer Don Wichern. "Sealing a bridge deck prolongs the life of the bridge, thereby pushing back the day when it will have to be replaced. It's just another way we are trying to maintain our system for as long as possible with the funds available."

Hot Times

There's one thing on every Missourian's mind today - how to deal with the heat.

Many of MoDOT's employees work in all kinds of weather. Our maintenance folks are experts at staying hydrated and taking breaks when needed. One of them is very concerned for you.

Barrel Bob, Missouri's work-zone spokesbarrel wrote a little piece for our blog today. We hope you enjoy it.

Gracious, people! The last time I was this hot, I was being extruded into existence at the barrel factory! But I was designed to take these temperature extremes. I'm a bit worried about you.

Missouri's work-zone spokesbarrel, Barrel Bob,
tries to provide his own bit of shade as he urges
travelers of all stripes to take extra care in the heat

From my spot here on the side of the road, I'm seeing some folks who treated today as any normal day. They're learning it ain't when they run out of gas or deal a breakdown on the side of the highway. That's a bad deal anytime, but when the world is superheated, the misery is quadrupled!

Do me a favor. Check your car before you head out. Do you need to get gas?

How 'bout them tires? Should you stop and get air or get that slow leak fixed?

If you need to call for help, does your phone have enough juice?

When was the last time you checked the coolant?

What about coolant for your body? Stocking up with water is a good idea for all travelers - those in vehicles, motorcycles and you self-powered movers on bikes and on your feet.

These are the kind of days you learn the true condition of your vehicle. Just try not to learn it on the side of a steamy road!

Nobody Likes a Pothole

It will soon be that time of year; the snow will begin to melt, temperatures will begin to warm up and before you know it we’ll hear the first sounds of spring…our tires falling into potholes. Potholes are annoying – period.

Potholes occur because of expansion and contraction of water under the pavement. This expansion causes pavement to bend and crack, leaving gaps or voids. When cars drive over these gaps, the pavement collapses and pieces of roadway are kicked out, creating a pothole. The more freeze-thaw cycles an area has (like most of Missouri), the more potholes you will see.

Roads with high traffic volumes have more potholes due to amount of use. Bridges and ramps, which receive more salt and snow removal chemicals in the winter, also are more prone to potholes. Older roads tend to have more, as you’ve probably noticed.

Our Maintenance crews try to get out and patch potholes for safety reasons, as soon as the weather allows. Repairing potholes during inclement weather, or when an immediate repair is needed to maintain safety, means using cold patch asphalt until a more permanent repair can be performed. These patches are quick to do, but only temporary.

When the weather warms up, hot asphalt patching of potholes begins. These patches usually take more time to fix, depending on size and location, but will last considerably longer.

The long-term solution to potholes is to reconstruct the pavement, but this is also the most expensive option that takes the most amount of time.

If you notice a pothole on a state route, try using MoDOT’s online form to let us know. So even though we all agree potholes are annoying, please be patient as our crews work hard to patch them as quickly and safely as possible.

For a better look at how roads deteriorate over time, view the Life Cycle of a Highway video: