One in six Logan County bridges structurally deficient

[January 08, 2018] 

LINCOLN

The Illinois Soybean Association assisted Logan County with a bridge study that has aided in decision-making in maintaining its bridges.

When the Logan County Regional Planning Commission met in October, one focus of discussion was an assessment of Logan County bridges. Logan County Highway Engineer Bret Aukamp presented a bridge study that the Illinois Soybean Association supported.

Aukamp said in summer 2016, the commission got money from the Illinois Soybean Association, which was looking for ways to help do some planning to improve agricultural commodity transportation in Illinois. The Association had already supported studies for a couple of other Illinois counties and Aukamp had seen some presentations, so he asked if they would be interested in doing one for Logan County.

Aukamp worked with the Illinois Soybean Association to "hone in" on something that would be beneficial to both the Soybean Association and Logan County. They decided to look at bridges with problems.

Aukamp went on to say, the county has 208 bridges that are 20 feet or longer and many of them are beginning to be in bad shape. Routine inspections of all bridges are done every two years to make sure they are safe for travel and each one is evaluated for needed repairs and replacements. He prioritizes where to use limited funds and leverage money as best as possible.

The study looked at the 20 worst bridges to figure out which ones would be the most beneficial to repair providing a benefit/cost ratio for each bridge.

To determine the benefit of each bridge and the costs for replacement the study considered adverse travel that would be caused if the bridge were not there and then added in the cost for people to drive and the costs of pollution.

The study looked at the various types of bridges and the number of vehicles travelling on them daily. Some bridges had 25 vehicles a day, while others had 500 or more.

Aukamp said these ratios varied from 7:1, all the way to 113:1 for a bridge on 600th Avenue just north of Emden. The 113:1 ratio was the best benefit/cost ratio.

Aukamp said when bridges are in pretty bad shape, they are described as "structurally deficient" and become eligible for federal funds. He said in 2006, there were about nine structurally deficient bridges and for the next several years there were about 13 structurally deficient bridges.

Aukamp said from 2012 onward that number skyrocketed. They found all kinds of problems with bridges such as cracked deck beams or piling underneath that was rotting and rusting.

Of the 208 Logan County bridges, 34 are now considered structurally deficient, which is nearly one out of every six bridges.

Aukamp said with the county highway department budget they can replace one bridge per year.

Looking at square footage, Aukamp came up with rough replacement costs. He said it can be between a quarter million dollars and $1.5 M just to rehab a bridge.

Aukamp said the benefit/cost ratios help him make better decisions and determine which bridges need to be replaced first. Bridges near the top of the list will be replaced before the others. Bridges with little travel are not likely to be repaired.

Aukamp said he is trying to lower the percentage of structurally deficient bridges. Five on the list have already been repaired or programmed for repair.

Commission Chairman Bill Graff asked about having another study done on more bridges.

Aukamp said another study could be done down the line to give the department some new numbers.

Commission members at the presentation were Bill Graff, Seth Goodman, Blair Hoerbert, Jeff Hoinacki, Gerald Lolling, Ryan Murphy, Chuck Ruben, Scott Schaffenacker, Becky Werth and Jim Vipond. County Highway engineer Bret Aukamp and Zoning Officer Will D’Andrea were also present.

[Angela Reiners]