Economic Impact of Closing Low-Volume Rural Bridges in Kansas

Eric J. Fitzsimmons, Ph.D.Tom Mulinazzi, Ph.D., P.E., L.S.Steven D. Schrock, Ph.D., P.E.

Mid-Continent Transportation Research SymposiumAmes, Iowa

August 15-16, 2013Session 3F: Local Roads Considerations

Background and Objectives

• The state of Kansas has approximately 25,500 bridges

• Limited county resources restrict rebuilding or repairing bridges

• Structurally deficient bridges

• Functionally obsolete bridges

• Bridge inspection and engineering studies have shown the need to close or repair/replace a low-volume bridge

• The decision to act on this lies with the county commissioners

Study Objective and Research Gap

• To determine a cost comparison of replacing and/or repairing a rural low volume structurally deficient bridge versus closing the bridge and finding the change in vehicle operating cost based on the proposed driver detour

• Very limited research in this area, however studies have investigated closing segments of rural roadway – particularly in Kansas (Babcock and Alakshendra, 2012)

KDOT Data

• National Bridge Inventory Database• Two-wheel path unpaved roads (very low volume)• Average Daily Traffic (ADT) = 25 vehicles per day or less• 1,321 bridges met this criteria

Data Reduction and Detour Length Determination

• Each bridge was verified that it existed through Google maps• Inspection dates were as far back as 1994• Variables included

– Latitude/Longitude, structure type, inspection date, deck area• In many cases bridges were removed or culvert installed• 992 total bridges were found to exist in the data set

Data Reduction and Detour Length Determination

• If bridge 380 was to be closed and a farm was located at point A:

– What is the detour distance from point A to point B?

– Distance measured in Google Earth

– Shortest detour length approximately

3 miles AB

Location of Structurally Deficient Bridges and Detour Length

Descriptive Analysis

• Significant number of structurally deficient bridges had a detour of less than or equal to 2 miles

• Most bridges were found to be steel followed by timber

• 6 bridges had at least an 11 mile detour

• Longest detour found was 20 miles in western Kansas

Analysis

• Study assumptions– Rural roadway volume and the typical number of daily trips was unknown

– 80/20 split cars and trucks

• Estimated user and infrastructure costs– $0.60 per mile for a car

– $1.00 per mile for a truck or farm implement

– $150,000 estimated bridge replacement cost by KDOT

– 75 year bridge lifespan

– $2,000 per year assuming yearly maintenance and inspection costs

Study Results

• Based on the stated assumptions a threshold was developed

• It was found a bridge should be closed with an ADT less than 8 and detour length less than 9 miles

• Increasing vehicle operating costs to the driver over the life of the bridge far outweighed the cost of a new bridge

Survey of Practice

• An electronic survey was conducted in March 2012• Sent to all 105 Kansas counties• 29 counties responded

Survey of Practice

Q1. Has your jurisdiction ever closed a bridge on a low-volume roadway?

• Saline County• Leavenworth County• Montgomery County• Sherman County• Generally a limited number or no bridges have been closed

during their careers

Survey of Practice

Q2. What criteria were used to determine that the bridges needed to be closed?

• Saline County’s plan• Maintenance costs and traffic operations• If land-locked, repair the bridge• Low-water stream crossing is always an alternative• Bridge substructure condition

Survey of Practice

Q3. Has your jurisdiction ever tried to close a bridge, but was unable to due to other reasons?

• Local politics• Land owners requested to keep the bridge open• County commissioners did not want to make the tough call• Counties have worked with the Kansas Historical Society to

keep a structurally deficient bridge open

Survey of Practice

Q4. Does your jurisdiction have a standard cost to repair a structurally deficient or functionally obsolete or unsafe bridge on a low-volume road?

• Most did not• Seven responses• $50 to $100 per square foot• $50,000 to $250,000 for typical bridge replacement

Survey of Practice

Q5. Would your jurisdiction be interested in an electronic copy of the final report?

• All of the counties responded “yes”

Now available online or through the Kansas DOT libraryhttp://ntl.bts.gov/lib/47000/47000/47089/KS-13-1_Final.pdf

Discussion and Conclusions

• A significant number of rural bridges in Midwest states are structurally deficient or functionally obsolete that are maintained by local jurisdictions

• Repairing or replacing these bridges are expensive for counties with limited infrastructure budget

• It was anticipated at the beginning of the study that a large number of bridges would be in the “close bridge” category

• This study was designed as a complimentary information in which county commissioners can use to determine if a bridge should be close or kept open to traffic

Acknowledgements and Contact Information

• Kansas Department of Transportation– Ron Seitz, Bureau of Local Projects

Steven D. SchrockAssociate ProfessorDepartment of Civil, Environmental and Architectural EngineeringThe University of Kansas2159B Learned Hall, 1530 West 15th Street785-864-3418schrock@ku.edu