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Motorists want to travel through work zones with as little inconvenience as possible. MoDOT tries to minimize travel impacts by shifting work times and using technology in work zones that provides valuable information to customers and by using innovative traffic control devices to promote efficient traffic flow. To measure the effectiveness of these strategies, MoDOT monitors the performance of work zones with the greatest potential to impact traffic each quarter. The goal is to minimize the number of times a work zone creates a traffic delay of 10 minutes or more.

In 2023, the highest number of delays and overall congestion occurred as compared to the previous five years. Calendar year 2025 is trending lower for both the number of delays and overall congestion as in 2024. When comparing YTD 2025 with YTD 2024, there is a 6% decrease in the number of delays and an 11% overall congestion decrease. MoDOT has monitored 512 work zones consisting of 974 work zone delays of at least 10 minutes and total congestion of 397 hours.

This quarter, pavement addition on I-70 in Northeast (Warren), and bridge work on I-55 in St. Louis were the largest contributing projects, causing 26 hours and 17 hours of congestion, respectively. These projects have contributed a total of 43 hours of the 193 hours (22%) of congestion this quarter. Pavement reconstruction/widening along I-70 has contributed to 116 hours of congestion. For the year, bridge improvement projects continue to be the largest contributor of delays at 186 (47%) hours of congestion. 

The target for the cumulative work zone congestion statewide was set at 588, an average of the completed previous three years of data. This will remain a rolling three-year average. The average is based on data from CYs 2022-2024.

Purpose of the Measure:

Work zones are designed to allow the public to travel through them safely and with minimal disruptions. This measure tracks the performance of significant work zones.

Measurement and Data Collection:

Work zone impacts are identified using automated data collection and visual observations. An impact is defined as the additional time a work zone adds to normal travel. Impacts resulting in a delay of at least 10 minutes are included in this report. The targeted hours of work zone congestion are based on previous years' data and an acceptable tolerance of 30 total minutes for work zone congestion statewide. The target for this measure is updated quarterly.