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The Construction Congestion Cost (CO³) System is a tool with which engineers can estimate the magnitude and impacts of traffic congestion, including its cost impact on road users, that can be expected during a construction project. Its name comes from the first two letters of COnstruction COngestion COst, on which the system focuses. From project conception through drafting provisions for maintaining traffic, CO³ provides a useful way for engineers to include construction congestion and its costs to users as an important variable in all project decisions.
CO³ measures the impact of congestion in two basic ways: (1) variables such as delay, diverted vehicles, and backup measure different characteristics of congestion and (2) user cost provides a common unit of measure with which to sum traffic impacts and compare them with construction cost. User costs consist of direct costs of increased travel distance due to traffic diversions and indirect costs that measure the impact of traffic delays and trip cancellations caused by congestion. CO³ helps us select among alternative methods of maintaining traffic during construction, and it helps us select contract period costs for contract provisions that provide incentives for reducing congestion impacts during construction.
CO³ Software and User Manual
The CO³ software is essentially a macro enabled spreadsheet. There are two separate versions of this spreadsheet: one for evaluating work zones with capacity/speed reductions, and another for evaluating work zones using traffic regulators (e.g. “flagger,” temporary signal).
The User Cost per Mile value for cars is the latest operating cost value published by the Internal Revenue Service. This value should be updated based on the release of new values, historically every six to 12 months. For trucks, an operating cost value was calculated from the 2003 Motor Carrier Annual Report (the latest available data), and indexed into 2023 dollars based on the Consumer Price Index (CPI). Please use the following values when using CO³.
|CO³ Cost Value
|User Cost per Hour ($/V hour)
|User Cost per Mile ($/V mile)
The User Cost per Hour values are based on Federal Highway Administration (FHWA) publication number FHWA-SA-98-079, "Life-Cycle Cost Analysis in Pavement Design." Currently, the Michigan Department of Transportation (MDOT) updates these costs yearly using the CPI, which follows the same methodology as detailed in the FHWA publication, with the above costs being based on the 2023 annual CPI value. These values can be revised more often if necessary.
CO³ Training and Other Information
For CO³ training, training requests, and software troubleshooting, contact Ben Krom at 517-636-4966.
For project level questions regarding inputs (diversion rates, volumes, etc.), contact Chris Brookes at 517-242-6486.
CO³ and CO³ Flag were developed by Robert I. Carr, Ph.D., P.E. et al. at the University of Michigan Department of Civil and Environmental Engineering, with financial support from MDOT.