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.

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."

Bridges Bounce



The wonderful thing about bridges,

Is bridges are flexible things.
The structure is made to move up and down,
Sometimes it feels they’re on springs.

Bill Emerson Bridge in Cape Girardeau, Mo.

My apologies to Tigger and his fans. I just couldn't help myself. 

The idea for the verse popped in my head one evening as I waited for a crash to be cleared from my lane on a Missouri River bridge. As cars and commercial trucks rumbled by, I felt a bounce that was a bit unnerving. It wasn't the first time I'd felt the bounce. It happens on any type of bridge - overpasses and elevated lanes included.

Luckily, several bridge experts work just a short elevator ride from my desk. They helped me to understand that bridges are designed with some flexibility built in. They’ve got to perform in temperature extremes – contracting and expanding with cold and heat – in still and windy conditions, and under differing weight loads.

That flexibility means there will always be some movement. In fact – the Golden Gate Bridge in San Francisco is built to swing up to 27 feet mid-span in the unlikely event of a 100 mph broadside wind!



Setting the supports for the Miami Bridge.

It's hard to understand how something that looks so stable and solid could move up and down, but have you ever walked on a board laid across two supports? The further apart the supports are, the more vibration you feel as you walk across the board. This vibration, called resonance, also plays a part in bridge movement as vehicles move across a span.



Designers and engineers have to strike a careful balance of distances and supports, because a too-stiff bridge has its own issues.

If you are ever stopped on a span and become uneasy with the bouncing movement, maybe this will help - MoDOT's bridge inspection teams, who sometimes use a special truck to view the undersides of bridges, sheepishly tell stories of seasickness suffered when they spend too much time in the bucket attached to the flexible arm of the truck parked on a bouncing bridge. They might be uncomfortable, but they’re never scared. They know why bridges bounce. And now, so do you!


Inspectors examine the underside of the
Hurricane Deck Bridge using a snooper truck.

Bridge Building Ballet

Imagine trying to build an overpass above one of central Missouri's busiest highways. You'd have to lift long, heavy steel beams across two lanes of highway and affix them to supports while imposing the least possible impact to traffic.

It takes a lot of choreography among people who can move quickly and easily amid seeming chaos. It's a lot like a large-ensemble ballet. And the professionals who set the first four beams for the U.S. 63/Route H overpass in Boone County are virtuoso.

In dance, timing is everything. In this case, everything was timed. The crews' arrival, the delivery of individual beams, the traffic interruptions. Everything had to happen in the correct order.

The beams arrived individually and each was connected to a crane

which hoisted them into place as a captive audience of travelers watched a few minutes of the performance.





Once the beams were aligned safely on the piers, traffic began to move below as carpenters and welders affixed the steel.











Meanwhile, another beam arrived on-site and the dance repeated until all were in place.

Soon, the completed overpass will be just another piece of the local landscape, but several groups of travelers will be able to say they saw this vital movement in the creation of a bridge. Thanks again, U.S. 63 motorists, for your patience!

Hybrid Composite Beams

If it works for boats, why not for bridges?


As part of its Safe & Sound Bridge Improvement Program, MoDOT received a $1 million federal "Highways for Life" grant to utilize hybrid composite beams on three bridge projects -- in Douglas, Shannon and Dade Counties. These innovative structural elements are much lighter than conventional steel or concrete beams, which make them easier to transport and install. The exterior of HCBs is fiberglass, materials also used to construct boats and sulfuric acid storage tanks. The fiberglass makes them more resistant to water and chlorides, and therefore longer lasting.


Check out some photos and the video below that explains this technology. Happy Sailing!







http://www.flickr.com/photos/modot/sets/72157627384391038/

500 Bridges, Safe & Sound!

One year ago, we were celebrating the completion of the 200th bridge constructed under the Safe & Sound Bridge Improvement Program.

Yesterday, that number climbed to 500.  Before the program is complete by the end of 2012, more than 800 bridges across Missouri will be rehabilitated or replaced.

We're more than halfway there! Better yet, the average closure of bridges across the state has been about 40 days -- that's half the time a typical bridge replacement takes.

How Do You Pour Concrete Under Water?

Bridges have always amazed me. As someone who works with engineers but does not have that background, the process of constructing a bridge just seems incredible. My burning question has always been about how the foundation is built and holds strong. Really, how DO you pour concrete under water?

How do you pour concrete underwater?

My question has been answered, and with a neat little graphic to boot. The New Mississippi River Bridge project in St. Louis is offering a virtual tour that answers all of your questions about how these massive structures take shape. Don't miss the pictures of the coffer dam, where crews are able to work on the riverbed.

If you're in the St. Louis area, you can see these steps in person. On the last Friday of each month, schedule a tour where you can see the action up close. Check out the specifics here. 

Light Up the Sky

D5411_CM_03, a photo by MoDOT Photos on Flickr.

The new Christopher S. Bond Bridge in Kansas City took on a whole new light on July 3, and it became a real blast.

The bridge features a unique lighting system with a series of interconnected color-changing panels - 106 of them - able to display thousands of colors in a variety of patterns. There are nine lighting packages that can be used throughout the year to reflect the city's seasons, holiday and regional events.

The inaugural lighting debut kicked off just minutes before the fireworks extravaganza celebrating KCRiverFest over the Fourth of July holiday.

Don't miss the rest of these photos on Flickr!

Happy Fourth of July!

If you gotta go, go big. This explosive video is two years old, but makes just as big of a bang today.
Happy Fourth of July!

Safe & Sound Bridge Program Reaches Halfway Milestone

Fourteen new bridges opened to traffic last week, pushing the number of completed Safe & Sound Bridge Improvement Program projects past the halfway point.

There are now 410 new or rehabilitated bridges that have been constructed all over the state, and on average, another is opening every two days. When completed, the Safe & Sound program will have repaired or replaced 802 of the state's lowest rated bridges. Just this year alone, 80 new bridges have been built.

The program's original goal was to complete 802 projects in five years, or by the end of 2013. At the current rapid pace, the program should be complete a full year early, or by the close of 2012.

So far, 231 new bridges have been constructed under MoDOT's design-build contract with KTU Constructors, and 179 bridges have been rehabilitated through the department's regular monthly lettings.

The average road closure associated with the Safe & Sound projects has been 40 days, or about half the time it normally takes to replace a bridge.

Currently 77 bridges are under construction, with another 12 scheduled to start next week.

Making Impossible, Possible

Moving something that weighs four million pounds seems impossible. Now imagine the four million pound object is 670 feet long and 55 feet above the Gasconade River. Well, MoDOT likes to make the impossible… possible.

The westbound lanes of the I-44 Gasconade River Bridge needed to be replaced and so to minimize motorist impact, MoDOT utilized an innovative method of bridge construction called bridge jacking. This method includes building a new bridge deck on a temporary substructure right next to the existing bridge, and when the new bridge deck is finished, sliding the new addition into place using hydraulics.

This amazing feat closed the westbound lanes of the I-44 Gasconade River Bridge for just 19 days, while traditional bridge reconstruction methods would have closed this same stretch for at least 60 days. Talk about a traffic headache reduction!

Know Before the Cones

It's the time of year when you're likely to see orange.Though MoDOT's construction budget is down, there are plenty of opportunities for those orange cones to appear in your windshield. Here are a few websites that can help you learn which highways have lane and bridge closures:


www.modot.org/tim - The map you use to check winter road conditions also provides the location for work zones. Use the interactive map link in the upper left corner to zoom in for a closer view.

www.modot.mo.gov/safeandsound - We're in the middle of a five-year program to fix 800 bridges. This summer, hundreds of bridges get a makeover. To complete the projects as quickly as possible, most bridges are completely closed. Go to the Safe & Sound site to learn which bridges are under construction, which are planned to start in the next several months and which will wait. The interactive map makes finding those on your routes easy.

www.modot.org/workzones - Visit this page to tell us how we're doing. Rate our work zones and let us know how we can improve. Do you have a suggestion or did we cause a problem? Let us know.

As always, you can call 1-888-Ask-MoDOT for questions, or visit www.modot.org.

Everyone Loves This Bridge!

Last week, beams were set on a bridge on Route U in Pettis County, near Sedalia. No big deal, really, since this scene has been repeated hundreds of times as MoDOT has completed 314 new bridges since the Safe & Sound Bridge Improvement Program got rolling in April 2009.

But this one was a little different, since one of the beams was displayed at the State Fair in Sedalia in August. Visitors to MoDOT's Highway Gardens were encouraged to sign the beam to demonstrate their support for new bridges in Missouri. And sign it they did ... by the thousands. One lady who lived nearby the bridge site signed it on the bottom "so that I can see it when I float underneath it next summer."

Now the beam is at its final resting place in a multi-span bridge over Spring Fork Creek. The latest signature added to the structure, as you'll see in the picture, is from one of the construction workers at the site. He and others like him will be plenty busy in 2011, when MoDOT and its design-build contractor KTU Constructors plan to build more than 300 new bridges across the state.

Golden Hour

 
The Eads Bridge photo above has been chosen for the cover shot and January photo for the 2011 American Association of State Highway and Transportation Officials calendar. It was taken by Cathy Morrison with MoDOT.
The photo shows the golden hour of Eads Bridge, a combined road and railway bridge over the Mississippi River at St. Louis, connecting St. Louis and East St. Louis, Illinois. Today the road deck has been restored, allowing vehicle and pedestrian traffic to cross the river. The rail deck has been in use for the St. Louis MetroLink light rail line since 1993.