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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. Fuel consumption and emissions benefits were modeled based on flow, delay, number of stops, and travel speed data are as observed in the field.
FINDINGS
The table below compares performance between the control site and test site resulting fuel consumption benefit of using DLLMS during the 11 week test period.
| Description | EB I-94 | WB I-94 |
|---|---|---|
| Length of advance warning area (ft) | 21,120 | 20,064 |
| Average hourly volume (veh/hr) | 990 | 1,207 |
| Number of weekdays DLLMS was operational | 55 | 55 |
| Number of hours in peak period | 2 | 2 |
| Total travel in vehicle miles | 435,600 | 504,526 |
| Average delay (sec/veh/10,000 ft) | 181.11 | 67.67 |
| Total delay in vehicle hours | 5,479 | 2,496 |
| Average number of stops per vehicle | 4 | 2 |
| Total stops per hour | 3,960 | 2,414 |
| Average operating speed (mi/hr) | 29.5 | 47.6 |
| Total fuel consumption (gallons) | 21,796 | 18,384 |
| Total fuel savings for the work zone during the worse period (gallons) | 3,412 |
The table below compares the vehicle emissions for the EB I-94 control site and the WB I-94 test site during a congested PM peak period. There was a 15.7 percent reduction in the amount of pollutants produced by vehicle emissions for WB I-94 with the installation of the
DLLMS.
| Description | Control Site EB I-94 | Test Site WB I-94 |
|---|---|---|
| Carbon Monoxide Emissions (grams) | 1,523,540 | 1,285,042 |
| Nitrogen Oxide Emissions (grams) | 296,426 | 250,022 |
| Volatile Oxygen Emissions (grams) | 353,095 | 297,821 |
Total Emissions (grams) | 2,173,061 | 1,832,885 |
| Percent Reduction in Total Vehicle Emissions per congested PM peak period | 15.7% | |
Evaluation of the Dynamic Late Lane Merge System at Freeway Construction Work Zones: Final Report
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