The Total Capital Costs of a Dynamic Shoulder System on US-23 near Ann Arbor are Estimated at $60 Million.

Researchers Used Before and After Operational Data and Surveys to Analyze a Dynamic Lane Using Inside Shoulders near Ann Arbor, Michigan.

Made Public Date

Summary Information

Active traffic management (ATM) aims to dynamically manage recurrent and non-recurrent congestion based on prevailing and predicted traffic conditions. Researchers analyzed the effectiveness of the US Route 23 Flex route opened by Michigan Department of Transportation (MDOT) in 2017 to mitigate peak-hour congestion, reduce incident response times, and improve safety. The Flex route uses the corridor’s 11-foot wide inside shoulders as dynamic lanes over a length of 8.5 miles. Researchers analyzed the performance of the Flex route, the safety of the adjusted roadway, driver perceptions, and the costs and benefits provided. Operational performance data was collected using various sources including probe vehicle data, microwave vehicle detection system reports, permanent traffic recorder data, ATM reports, and incident clearance data. Real-world safety data was collected before the lane was installed, from 2012 to 2015, and after, from 2018 to 2019.

The capital costs of the Flex route installed on US-23 (Table 1) totaled $60 million, with $3 million going towards software module, $17 million going towards ITS construction, and $40 million going towards shoulder construction, as reported by MDOT in 2021.

Table 1. Capital costs of the US-23 Flex route



Useful Life


Unit Costs

Software Module


15 years



Harden Shoulder


25 years

18 (Lane-mile)


Telecommunication (modified to be ITS Construction)


25 years



TOTAL $60,000,000      


The annual operation and maintenance (O&M) costs were estimated by the FHWA’s Tool for Operations Benefit/Cost Analysis (TOPS-BC) Version 4.0., which includes $350,000 for software module, $350,000 for ATM Traffic Operations Center hardware, $1 million for harden shoulder (2.5 percent of the capital costs of shoulder construction), and $340,000 million for ITS (2 percent of the capital costs of ITS construction).

Evaluation of an Active Traffic Management System with Part-Time Use of the Inside Shoulder

Evaluation of an Active Traffic Management System with Part-Time Use of the Inside Shoulder
Source Publication Date
Kassens-Noor, Eva; Peter T. Savolainen; Timothy J. Gates; Meng Cai; Qiuqi Cai;
Hisham Jashami; Megat-Usamah Megat-Johari;Travis Decaminada; Gabrielle
Herin; and Ali Zockaie
Prepared by Michigan State University for the Michigan Department of Transportation
Other Reference Number
Report No. SPR-1706
System Cost

Flex Route ATM System along 8.5 mile-segment of US-23: $60 million

System Cost Subsystem