September 2018 Vol. 26, No. 3

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Historic local bridges: What you need to know

I recently had the opportunity to visit with two of Minnesota’s foremost experts in local historic bridges: Kristen Zschomler, director of the Minnesota Department of Transportation (MnDOT) Cultural Resources Unit, and Patti Loken, manager of the MnDOT State Aid local bridge funding program.

Kristen supervises 12 staff dealing with historic issues for roads and bridges and for rest areas, buildings, and other features that may be affected by transportation projects. Work includes facilitating historic-related conversations with the Federal Highway Administration (FHWA), Federal Railroad Administration (FRA), Corps of Engineers (COE), and State Historic Preservation Office (SHPO). Patti manages the local bridge funding program and has been instrumental in developing strategies for dealing with historic bridges.

After dealing with local historic bridges for years as a county engineer, I learned some things I would like to share with you.

Alan Forsberg, P.E., retired Blue Earth County Engineer

Swayback bridge
Redwood County's swayback bridge features an overflow section for high flows.
Photo: MnDOT

Does age alone determine if a bridge is historic?

Age is only one consideration of whether a bridge is historic. Also important is the historic integrity of the bridge, its role in opening the area for early settlers, and relationship to other historic features. Its engineering characteristics, especially innovative design, are very important. It is not surprising that 80 to 85 percent of historic bridges are on the local system. Bridges were essential to early development and were often built by local governments before the state transportation system was developed.

Do historic bridges have public value—how do they contribute to the “Public health, safety and welfare?” With 12,000 local bridges and 900 on the replacement priority list, how is investment in historic bridges justified?

There is value in preserving history for its own sake, celebrating the past to benefit the future, and understanding our engineering heritage. There is also an economic tourism benefit in preserving historic structures, such as generated by the Stone Arch Bridge in Minneapolis, the Aerial Lift Bridge in Duluth, or Jones Ford Bridge near Amboy. In some cases, historic rehabilitation can cost less than replacement.

As democratic evidence of the value of preserving these historic resources, our elected officials have recognized the public value, crafted state and federal laws, and invested tax dollars to preserve and rehabilitate historic bridges.

mult-plate arch
Todd County's mult-plate arch has a rock façade and early steel plate design.
Photo: MnDOT

What are the federal and state laws protecting and preserving historic bridges?

If federal funds are used for a project or if a federal permit is needed, the National Historic Preservation Act of 1966, Section 106, and in some cases Section 104, applies. In Minnesota, the Minnesota Historic Sites Act and Minnesota Environmental Protection Act apply. Both federal and state acts have rules on implementation. The definition of when a bridge is historic is a bit fuzzy. All this creates a complex situation when a local government is faced with a decision about an obsolete and deficient structure.

How are the federal and state historic bridge laws implemented in Minnesota?

Fortunately, MnDOT State Aid has taken a leadership role in helping local governments. In the 1990s, local governments were often not clear on how to proceed. MnDOT surveyed local bridges constructed before 1956 and determined which bridges were eligible or on the historic register.

In 2010 this list needed updating. A survey was done of problems local governments were having with historic bridges, the earlier list was reviewed and updated, and a report was prepared on each of the eligible or listed bridges. This list includes about 3 percent of all local bridges. The report documented the bridge description and condition and included a management plan for maintaining the bridge as a historic structure. Historic American Engineering Record documentation requirements are met by the reports.

When the federal process must be followed due to funding or permits, the report provides a head-start. Each report is located on the MnDOT Bridge Office website. Why a bridge is historic, and a discussion of its historic nature, is already done for you. See the MnDOT website, A-Z, Historic Bridges, for a wealth of information on historic bridges in Minnesota.

The challenge is to meet the local transportation need while respecting the historic value of a structure. The goal of the historic review process is to foster a conversation between all affected parties on how best to meet this challenge.

Is help available?

Franklin Ave bridge
The new deck and substructure repairs of the Franklin Avenue bridge
in Minneapolis respect the original design.

Photo: MnDOT

If you have an eligible historic bridge or one on the historic register, you are fortunately not on your own. Help is available!

Suggested first step—contact Kristen Zschomler or Katie Hawn Schruing, MnDOT Cultural Resources staff. The Cultural Resources Unit may also be able to assist with grant applications for historic funding. MnDOT’s Patti Loken can assist with funding options and status. David Conkel, State Aid bridge manager, can assist with structural preservation and rehabilitation options. There are several bridge engineering firms with historic bridge expertise.

The FHWA, COE, and SHPO will become involved depending on funding and permits. After groundwork is laid with MnDOT State Aid and Cultural Resources and perhaps an assisting bridge engineering consultant, direct coordination with these agencies and development of a collaborative relationship is important in moving your project forward. (Note: SHPO is no longer an independent agency but is now part of the Department of Administration.)

As always, one of the most beneficial sources of information are your professional county engineers.

Historic bridge preservation project examples

After 10 years, significant progress has been made in preserving historic bridges, and there are many successful examples. See the MnDOT Bridge website for examples in both the Twin Cities metro and Greater Minnesota areas. Some excellent ones are pictured on this page.

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