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Report No.
2 Government Accession No.
KS-09-4
Title and Subtitle
Economic Impact of Closing Low-Volume Rural Bridges
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Author(s)
E.J. Fitzsimmons, T.E. Mulinazzi, S.D. Schrock, R. Roth
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Performing Organization Name and Address
The University of Kansas
1530 W. 15th Street
Lawrence, KS 66045-7609
12 Sponsoring Agency Name and Address
Kansas Department of Transportation
Bureau of Materials and Research
700 SW Harrison Street
Topeka, Kansas 66603-3745
15
3
Recipient Catalog No.
5
6
Report Date
November 2012
Performing Organization Code
8
Performing Organization Report No.
10
Work Unit No. (TRAIS)
11
Contract or Grant No.
13
Type of Report and Period Covered
14
Sponsoring Agency Code
K-9063-01
Supplementary Notes
16 Abstract
The State of Kansas has approximately 25,464 bridges that are located on state, county, and city roadway networks. As of May, 2012
approximately 1,229 bridges on very low volumes roads were determined to be structurally deficient and candidate structures to be
potentially closed, replaced or repaired. This study was designed to provide critical information for county commissioners or practicing
engineers by providing critical information including: (1)Where structurally deficient bridges on low-volume roads are located in
Kansas; (2) How long is the shortest drivable detour if the bridge were to be closed; (3) Whether to recommend closing or repair/replace a
bridge based on detour length and Average Daily Traffic (ADT); and (4) Results of a state-wide survey of country road supervisors,
county engineers their experience with closing a rural bridge on a very low-volume roadway. This study found that many of the
structurally deficient bridges have a detour of two miles or less, steel bridges were the most common structurally type of deficient bridge
in Kansas, and candidate bridges for closing had and ADT under 8 vehicles and detour length of nine miles or less.
17 Key Words
Rural Bridges, Structurally Deficient and Functionally Obsolete,
Travel Time and Detour Length, Low-Volume Roadways
18 Distribution Statement
No restrictions. This document is available to the public through
the National Technical Information Service www.ntis.gov.
19 Security Classification (of
this report)
Unclassified
21 No. of pages
8
20 Security Classification (of
this page)
Unclassified
Form DOT F 1700.7 (8-72)
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22 Price
Economic Impact of Closing Low-Volume Rural Bridges
Final Report
Prepared by
Eric J. Fitzsimmons, Ph.D.
Thomas E. Mulinazzi, Ph.D., P.E., L.S.
Steven D. Schrock, Ph.D., P.E.
Rachel Roth
A Report on Research Sponsored by
THE KANSAS DEPARTMENT OF TRANSPORTATION
TOPEKA, KANSAS
November 2012
© Copyright 2012, Kansas Department of Transportation
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NOTICE
The authors and the state of Kansas do not endorse products or manufacturers. Trade and
manufacturers names appear herein solely because they are considered essential to the object of
this report.
This information is available in alternative accessible formats. To obtain an alternative format,
contact the Office of Transportation Information, Kansas Department of Transportation, 700 SW
Harrison, Topeka, Kansas 66603-3754 or phone (785) 296-3585 (Voice) (TDD).
DISCLAIMER
The contents of this report reflect the views of the authors who are responsible for the facts and
accuracy of the data presented herein. The contents do not necessarily reflect the views or the
policies of the state of Kansas. This report does not constitute a standard, specification or
regulation.
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ECONOMIC IMPACT OF CLOSING
low-volume rural bridges
Thomas E. Mulinazzi, Ph.D, P.E., L.S.
Professor of Civil Engineering
The University of Kansas
2150 Learned Hall, 1530 W. 15th St.
Lawrence, Kansas 66045
Phone: 785-864-2928
Email: tomm@ku.edu
Eric J. Fitzsimmons, PhD.
Lecturer / Post-Doctoral Researcher
The University of Kansas
2159A Learned Hall, 1530 W. 15th St.
Lawrence, Kansas 66045
Phone: 785-864-1921
Email: fitzsimmons@ku.edu
Steven D. Schrock, PhD., P.E.
Associate Professor of Civil Engineering
The University of Kansas
2159B Learned Hall, 1530 W. 15th St.
Lawrence, Kansas 66045
Rachel Roth
Layout Designer
The University of Kansas
Lawrence, KS 66045
Background
The State of Kansas has approximately 25,464 bridges that are located on the state, county and
city roadway network. As the infrastructure in Kansas ages, bridges can become structurally
deficient or functionally obsolete. The Kansas Department of Transportation (KDOT) defines
a bridge as structurally deficient if an inspectors determines the bridge deck, superstructure,
substructure, culverts and retaining walls are not able to support today’s federal legal
loads (KDOT, 2008). A bridge that is defined as functionally obsolete consists of design
characteristics, which could include narrow width, inadequate clearance beneath, condition
of the structure, or deficient approaching roadway alignment (KDOT, 2008). Limited research
has been performed that specifically investigates advantages and/or disadvantages of closing
a bridge on a rural low volume road. The objective of this research project was to determine
a cost comparison of replacing and/or repairing a rural low volume structurally deficient
bridge, versus closing the same bridge and finding the change in vehicle operating cost based
on the proposed driver detour.
Data
The structurally deficient bridges located on Kansas rural low-volume roads were identified by
the Kansas Department of Transportation in May, 2012 using the National Bridge Inventory
Database (NBI). These bridges were located on two-wheel path roads where the average daily
traffic (ADT) was estimated to be 25 or under. A total of 1,229 bridges met these criteria. The
earliest bridge inspections occurred in 1996 with the newest inspections occurring in 2012.
The identified bridge data also included the latitude and longitude as well as the type of bridge
(Concrete, Steel, Masonry, or Timber)
Kansas Department of Transportation. What are Deficient or Obsolete Bridges?
Available: http://www.ksdot.org/KsBridgesDefObs.asp, accessed September, 2012.
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MAP COLOR PALETTE
NORTH ARROW
N
detour length 0–2 miles
detour length 0–2 miles
detour length 2–6 miles
detour length 0–2 miles
detour length 2–6 miles
detour length over 6 miles
detour length 2–6 miles
detour length over 6 miles
Figure 2. Location of structurally deficient bridge and respected detour length
detour length over 6 miles
Analysis and driver detour length determination
Using the latitude and longitudinal coordinates provided for each
bridge, each bridge structure was identified in Google Earth. The
research team ensured, based on the coordinates, that: (1) the
bridge existed on the 2012 aerial imagery knowing the inspector
data may have been off, and (2) that the existing bridge had not
been closed, replaced, or converted to a culvert or an engineered
low-water stream crossing. After the initial screening, a total of
992 structurally deficient bridges were identified.
With an assumption that a vehicle could safely detour around
one of the identified structurally deficient bridges, the research
team investigated the length of the shortest driver detour around
each of the 992 identified bridges. To determine the short driver
detour length, the structurally deficient bridge was identified on
Google Earth, adjacent private properties were investigated to
ensure farmsteads would not be landlocked if the bridge were to
be closed, and there was a safe detour route that included a paved
or two/three wheel path gravel road. The driver detour length was
assumed to be the length a vehicle had to travel out of its way to
get to the nearest intersection after the closed bridge. For example,
if a closed bridge was located on one side of a one-mile grid, a
driver detour length of two miles was recorded since the vehicle
would have to travel one mile whether the bridge was closed or
not. Shown in Figure 1 are the number and types of bridge with
the respected driver detour length.
As shown in Figure 1, 648 out of 992 bridges (approximately
65%) had a potential driver detour of 2 or fewer miles which
indicates if these bridges were to be closed, a relatively short
driver detour would be required of the driver. Also shown in
Figure 1, a total number of six structurally deficient bridges with
a driver detour length of over 11 miles were found. Based on
the driver detour length alone, these bridges would be excellent
structures to be considered for repair or replacement. Overall, the
number of structurally deficient bridges was much higher for steel
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bridges than any other type of bridge material. With the driver
detour length assigned for each structurally deficient bridge, the
locations of the bridges were plotted using latitude and longitude
as shown in Figure 2.
As shown in Figure 2, a significant number of structurally
deficient bridges on rural low-volume roads are found generally
in the northern and eastern counties of Kansas. The dots in yellow
indicate bridges with the longest driver detour length of over 6
miles, and the green dots indicate bridges with the shortest driver
detour lengths of 2 miles and under. Very few bridges, let alone
structurally deficient bridges, were found in the southwestern part
of Kansas due to geography and non-existing rivers and streambeds.
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CONRETE
STEEL
MASONRY
423
TIMBER
400
300
200
143
100
79
145
50
43
30
0
4
0-2
3-4
16
13
11
3
1
5-6
3
1 5
7-8
4
8
0 2
9-10
0 1 0 0
11-12
0 1 0 0
13-14
0 0 0 0
15-16
0 1 0 2
0 1 0 0
17-18
19-20
DETOUR LENGTH (MILES)
Figure 1. Number and type of bridges versus detour length
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REPAIR OR REPLACE BRIDGE ZONE
10
CLOSE BRIDGE
1
1
10
20
AVERAGE DAILY TRAFFIC (ADT)
Figure 3. Determining bridge closure / repair / replace based on ADT and detour length
Analysis and driver detour length determination continued
knowing the driver detour length for each structurally deficient
bridge, vehicle operating costs can be established. For this
project, it was assumed the structurally deficient bridge is located
on a two-wheel path secondary roadways where the ADT was
25 vehicles or less. It was assumed that the operating cost for
a passenger car was $0.60 per mile and for a large-truck/farm
implement was $1.00 per mile. It was also assumed than an 80/20
split between passenger cars and large truck existed for each
bridge ADT. For example, if the ADT was estimated to be 10, 8
vehicles would be passenger cars and 2 vehicles would be large
trucks. The research team assumed the 80/20 split would account
for season changes when planting and harvest occurred.
is very low ADT and a detour less than 9 miles, justification could be
made to close the bridge based on vehicle operating costs.
Discussion and Conclusions
Once vehicle operating costs were established, a conservative
bridge replacement cost was determined by the research team
and representatives from KDOT. A bridge on a rural low-volume
roadway replace cost was estimated to be $150,000 with a
lifespan of 75 years. This equals approximately $2,000 per year
assuming the yearly maintenance cost and periodic inspection
costs was included. Knowing the price of replacing the bridge at
an annual rate, the driver detour length, and vehicle operational
costs, Figure 3 was developed.
As Kansas bridge infrastructure ages on low-volume roadways,
the cost of repairing or replacing a structurally deficient bridge
can be a serious hardship for any county. This research project
investigated the economics of closing a structurally deficient
bridge by quantifying driver detour length, vehicle operating costs,
and bridge replacement costs. Locations of structurally deficient
bridges were provided by KDOT and their respected detour
lengths determined. It was found that there are 648 structurally
deficient bridges, if closed, would result in a driver detour length
of 2 miles for less. Many assumptions were made by the research
team and KDOT including vehicle operation costs and bridge
replacement cost with known data limitations. Conservative values
for vehicle operating cost for a passenger car and a large-truck
were determined to be $0.60 and $1.00, respectively, and bridge
replacement cost was set at $150,000 with a 75 year life-span.
It was anticipated that this study would have resulted in a large
number of bridges in the “closed bridge” category (see Figure 3).
However, in reality the number of vehicles daily traveling on these
bridges need to be very low with a short driver detour.
As shown in Figure 3, a relationship was developed between
driver detour length and ADT on the road the structurally
deficient bridge was located on. Based on the previous section
which developed a yearly cost to replace a bridge, the vehicle
operating cost and detour length were then computed and
compared to the bridge replacement cost. As shown, the cost of
operating a vehicle and adding a detour due to a bridge closure is
much higher than the cost of replacing a bridge. However, if there
Overall, the research team found an genuine interest by local
highway agencies in Kansas that are forced to work with county
commissioners in determining an economical plan to close or
repair a rural bridge while considering the safety of drivers. The
research team believes this study provides a basic framework for
discussion between commissioners and engineers in determining
if a structurally deficient bridge on a rural low-volume roadway
needs to be closed on repaired/replaced.
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Figure 4. Counties that responded to research project survey
In March, 2012 the research team conducted a survey of
practice by contacting county engineers and road supervisors
in all of the 105 counties in Kansas. The survey was designed
to evaluate whether counties in Kansas have considered or have
closed bridges on rural low-volume secondary roads. A total of
29 counties responded as shown in Figure 4, which represents
all geographical areas of the state. The list of questions and
summary of answers are as follows.
Q1. Has your jurisdiction ever closed a bridge on a rural
low-volume roadway?
A rural low-volume roadway for this study is considered
gravel or dirt with two wheel paths. Counties reporting bridge
closures: Saline County has closed approximately 28 bridges
since 2005, Leavenworth County is currently attempting to
close bridges, Butler County has closed six bridges in the last
23 years, Montgomery County has closed four bridges in the
past ten years, Sherman County converts closed bridges to
non-engineered low-water stream crossings with no concrete
bottom or tube. Generally, all responding county engineers /
road supervisors stated that bridges have not been closed during
their careers.
Q2. What criteria were used to determine that the bridge(s)
needed to be closed?
Many reasons were given by counties that included the
following: Saline County proposed a bridge closure program
which has been accepted by commissioners after careful
explanation. Many counties reported that maintenance costs
and traffic operations were two very important variables.
Counties also reported that land-locked farmstead property
also heavily influence the need to repair a bridge. Almost all of
the counties reported that an non-engineered low-water stream
crossing is always considered for an alternative. Two counties
reported that the decision to close a bridge was based on the
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bridge substructure condition. One county reported a bridge may
be considered for closure if it is located in a flood-prone area, and
finally all counties reported that local politics heavily influenced the
decision to close or repair a bridge.
Q3. Has your jurisdiction ever tried to close a bridge, but was
unable to due to other reasons?
Responses from the counties indicated that only a few cases of
proposed bridge closure met resistance from the public. One county
reported included local politics, three counties reported that the land
owner requested the bridge remain open, and one county reported
that the county commissioners did not want to make the tough call
to close a bridge. Additionally, one country reported resistance but
found a fair and friendly way to work with the Kansas Historical
Society to keep a bridge opened.
Q4. Does your jurisdiction have a standard cost to repair a
structurally deficient or functionally obsolete, or unsafe bridge
on a low-volume roadway?
The responses for this question indicated that many counties do not
have standard cost to repair or replace a bridge. However, it was
found that seven counties did and that many did the repair work
in-house. Prices indicated by the respondents included a price per
square foot of $50 to $110. For counties that responded based on
bridge replacement cost, the prices ranged from $50,000 to $250,000.
Q5. Would your jurisdiction be interested in an electronic copy
of the final report?
All of the counties that responded to the survey stated they would
be interested in the findings of the report. This indicates that bridge
closure on rural low-volume roadways is an important topic as
counties are faced with aging bridge infrastructure.