A dynamic late lane merge system decreased vehicle stops by 47 percent at a highway work zone in southern Michigan.
Case study of wok zone ITS applications in Kalamazoo, Michigan
Made Public Date


United States

Evaluation of the Dynamic Late Lane Merge System at Freeway Construction Work Zones: Final Report

Summary Information

This study evaluated the effectiveness of a dynamic late lane merge system (DLLMS) installed at work zones on I-94 during the 2006 construction season in southern Michigan. The system used microwave traffic sensors, wireless communications, and a series of portable dynamic message signs (DMS) to direct drivers when to merge. When congestion was detected in the open lane (lane without the tapered closure) and average traffic speeds dropped below a preset threshold level of 35 mi/hr, dynamic message signs upstream were activated to advise drivers to “Use Both Lanes to the Merge Point” to preempt queuing and improve traffic flow.


Evaluators compared freeway performance data collected at the DLLMS site with data collected at the control site equipped with only traditional work zone controls. A statistical analysis was performed to quantify the differences in mean travel time delay, the mean travel speed, and crash frequencies, and evaluate the economic viability of the system.


Results from t-testing indicated there was a statistically significant difference in performance at sites with and without DLLMS.

Description (congested PM peak)
Control Site
EB I-94
Test Site
WB I-94
Average travel time (sec/10,000 ft/veh) (pre-taper)
Average travel speed (mi/hr) (pre-taper)
Average number of stops per 10,000 ft/veh (pre-taper)
Average delay (sec/10,000 ft/veh) (pre-taper)
*Average total throughput (veh/hr)
990 (269)
1207 (172)
*Average percentage of merges at the taper
49.15 (53.33)
66 (74.1)
*Average percentage of merges prior to the taper
50.85 (46.67)
34 (25.9)
*Note: Total of all vehicles (commercial motor vehicles only)

A benefit-to-cost analysis conducted during the study. Results indicated the DLLMS is cost effective where the dollar value of motorists time can exceed $4.85 per hour. The analysis consisted of multiplying the value of motorist time by the travel time saved, adding the related fuel savings, and comparing this value to the actual cost of the system. With respect to travel time benefits, travel time savings were converted to a monetary value based on estimates of what drivers would be willing to pay for travel time savings. Note that safety benefits were not included in the analysis since the calculated change in crash frequency was not statistically significant.

Evaluation of the Dynamic Late Lane Merge System at Freeway Construction Work Zones: Final Report

Evaluation of the Dynamic Late Lane Merge System at Freeway Construction Work Zones: Final Report
Publication Sort Date
Datta, Tapa; Catherine Hartner; and Lia Grillo
Michigan DOT
Other Reference Number
Report No. RC-1500

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