College Street Pedestrian Bridge

College Street P e d est r i a n B r i d g e

The first bridge was erected on the site in 1839. Burned down by soldiers in 1862, it was rebuilt in 1864 only to be burned a second time in 1915. The existing truss bridge was rebuilt that same year.

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City of Bowling Green / Warren County Greenbelt Commission Bowling Green, Kentucky Engineering

Bridging the Past to the Future

SHOWCASE TWO

A triple-span metal truss bridge across the Barren River has connected Bowling Green, Kentucky, to the northern portion of Warren County since 1839. The College Street Bridge was originally built in 1915 and provided vital access for residents and commerce. No longer used for vehicular traffic, GS&P and the city utilized sustainable practices to completely restore and transform it into a pedestrian bridge, connecting visitors to the greenbelt system and providing a panoramic view of the river. Embraced by the community, the bridge has hosted numerous events, including weddings and festivals, demonstrating the city’s commitment to improving the quality of life for its citizens.

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ABOVE LEFT TO RIGHT Dangerous holes in asphalt covering the bridge prevented some sections from being used by the public. Across the entire bridge, deterioration from rust was resulting in reduced load limits.

Massive amounts of asphalt and concrete had to be carefully cut off the bridge deck in preparation for the restoration. Construction crews hand-bolted each locally harvested pine timber plank to the deck. Galvanized metal clips were developed to connect the timber deck planks to the truss stringers without requiring drilling or damaging the stringers. Readily available hardware was used to cut down on costs and support the park system’s self-maintenance goals. The completed bridge deck is soft on the feet and quiet to the ears.

TEAM

INTERVIEW /

Michael A. Flatt, P.E.

PIC

Ted Kniazewycz, P.E.

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Ted Kniazewycz, P.E.

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T e d K n i a z e w y c z , M i k e F l at t

Describe the College Street Pedestrian Bridge project.

The city of Bowling Green has one pedestrian bridge in their inventory, and they needed help bringing it up to standards primarily because of problems with the integrity of the deck. We were asked to take a look and offer options on how to enhance the bridge and best maintain the structure’s integrity.

MIKE: There was very strong public sentiment to get this project done.

TED:

What is the bridge’s current main use, and why was there a need for a new bridge?

Before you started on the bridge, was it completely out of service or was it just starting to deteriorate?

MIKE: It’s now more about budget than looks these days.

the centerpiece and keystone of their park

In keeping with its history, the city wanted to repair, rather than replace, the old truss bridge. What are some of the inherent challenges of repairing it?

Basically, it’s very labor-intensive to inspect and maintain the bridge, which drives the cost up. It’s also the reason the number of truss bridges in existence falls every year.

TED:

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It was to the point where sections of it were closed off and it had load limit restrictions. Before we got the plans fully developed, they closed the bridge because holes had developed in the deck.

In its day, the truss bridge provided the ability to span a fairly long distance. They were primarily using cast iron, and when structural steel hit the market, like we use today, beams could span distances as long as trusses, and even further. Most old truss bridges have now been replaced with a girder bridge because you can build at a lower cost.

TED:

TED:

Was the public involved in the planning and design of the bridge?

Within developing the park system, the public played a big role identifying how this bridge could support the connectivity of the system. In meetings with the parks service, the public felt that this was a vital link. They wanted it to be a showcase for their city and wanted it to be more than just a walkway.

ted:

SHOWCASE TWO

The bridge is really the centerpiece and keystone of their park system because it provides a connection from their main park in downtown to the greenway system. This bridge was the vital component they needed to connect the two areas. They had received special federal funds to rehabilitate the bridge, and they saw this as an opportunity to tie the system together. The bridge is also used for various private functions like weddings and parties so the city wanted something that would be special and that would connect back to the history of the bridge, which dates back to 1839.

TED:

What are the advantages of a truss bridge?

What were some of the options GS&P presented to the city?

The bridge had numerous problems, some dealing with the structural steel, some dealing with the deck itself. With the structural steel issues, we identified areas that needed to be replaced and put them in a priority order, so that they could address the worst ones first as their budget allowed.

The deck had been resurfaced two or three times in the past using asphalt on metal, so we could obviously point out the inherent problems of that system because they could see firsthand what was happening to the bridge. We presented the option of using concrete, which is standard on bridges.

But, we also pointed out that the extra load that the concrete TED:

would put on the bridge would probably put a limitation on pedestrian uses.

What were the key reasons the client ultimately chose to use timber instead of concrete?

We brought up the idea of using timber for several reasons. It’s more sustainable, it gives the bridge a softer, more attractive look and because it more than likely would have been a wood deck when the bridge was first built. Also, since they wanted to tie back to the bridge’s history, we felt this solution was more in line with the original. Timber was also a viable alternative because of the extra load associated with using concrete. And timber should have a life of 20 years or longer, at least, with good maintenance.

TED:

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SHOWCASE TWO

the sound and feel of it when you walk on it are very nice

Using sustainable products was very important to the client. What type of wood did they choose and why?

They chose to use pine, which is a very renewable source and it’s locally available. The lumber was also pressure treated with a system that does not put chemicals into the environment. Also, it’s resilient, and the sound and feel of it when you walk on it are very nice. They liked that it was green since it was part of the park system, and that was a big issue with the public and the park system since they actually operate the bridge.

TED:

MIKE: I think another big reason for using timber is that it feels like you’re part of the park system and not on a street.

Did the use of timber also save them money?

Yes, because the city can maintain the bridge themselves. They actually purchased the lumber for the deck directly from the lumber supplier because they could save money doing that instead of going through the contractor.

They also purchased about 10% extra material so if a board got damaged, their own crews could do the repairs. They liked the aspect of being able to do their own maintenance.

TED:

get any kind of growth on the timber off, and seal it at least every two years. We also advised them not to let leaves accumulate under the bridge, which causes moisture to get trapped and causes rusting. They’ll also need to touch up the paint occasionally instead of letting it rust, pretty minor things that they felt their crews could handle — nothing out of the ordinary or complex, which is exactly what they wanted.

You mentioned weight as a factor with concrete bridges. Does the use of timber allow the bridge to handle more pedestrians?

Yes. By using timber, it allows more people to be able to occupy the bridge at one time. Using timber takes off dead load from the bridge, which allows you to have more live load on it. Also, they can have a larger service vehicle on the bridge without causing any kind of issues.

TED:

What were some of the biggest challenges you faced on the project?

Because of the age of the bridge, we had to make some of the steel repairs with specially fabricated components. We ended up combining readily available pieces into a system that would work. For example, the old bridge had these cast-iron bars, which are not available anymore. We replaced those with standard, readily available, hardware-like turnbuckles, clevises, threaded rods, and things that they could maintain in the future.

TED:

MIKE: This also allowed us to stay within their budget, which was not a lavish budget in any way, but specially made pieces would drive the price up.

An interesting local fact is the color — Garvin Green. What is the special significance?

In the late 1980s, early 1990s, when the bridge was in disrepair, it was initially taken over by local philanthropist David Garvin. He spent quite a bit of money rehabbing it, and he came up with the paint color, so it’s called Garvin Green. If you go to the local paint store, that is what you ask for and that is what they use.

TED:

What aspects of this project make you especially proud?

What kind of maintenance will the city need to do?

I am pleased at the overall look of the boards on the deck. It really looks good. I’m also very proud of the fact that we were able to use readily available materials today to

TED:

The recommendations we made to them were to pressure-wash the bridge once a year after the leaves fall to

TED:

shy of its 100th birthday from the last improvement.

Will the bridge still exist 100 years from now?

They may have to do a major rehab on some of the steel above the deck sometime in the future, but with proper maintenance, absolutely. ■

TED:

You don’t necessarily have to automatically replace something — it can be rehabilitated and still be successful. And we are very proud and pleased that our clients are extremely happy with the outcome. They were put under the gun by the public to get this job done and do it in such a way that it will continue to be a feature of their park and trail system. We helped them do that, and everyone is very happy.

MIKE:

This is a bridge that in its original conception was built in the 1800s, then had an improvement in 1915. It is now 2009, and we are a couple of years

Ted Kniazewycz, P.E., has more than 20 years’ experience with new bridge design, bridge inspection services, and development of repair and rehabilitation plans. As project manager and project professional for College Street, Ted led the field inspection and plan development process. Michael A. Flatt, P.E., serves as GS&P’s division vice president and has more than 30 years’ experience in transportation planning, design, construction, and management. As principal-in-charge for College Street, Mike’s leadership, direction, and guidance insured that the project was delivered on time and exceeded the client’s expectations.

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go back and retrofit a structure from 90 years ago. It’s just thinking outside the box: not saying “it can’t be done,” but instead figuring out how it can be done.

SHOWCASE TWO

Embraced by the community, the bridge has hosted numerous events, including weddings, family reunions, and cultural events, demonstrating the city’s commitment to improving the quality of life for its citizens. Providing a panoramic vantage point, visitors enjoy views of the river, downtown, park system, and nearby waterfall.