In work zones that use reversible control, two opposing directions of traffic are required to share one lane, typically with flaggers stationed at each end to alternate the direction of flow. Where low volume access points, such as side roads and driveways, are present in the work zone, disruptions to operations and safety issues can be a concern. Researchers evaluated potential traffic control methods to mitigate wrong-way movements from these low volume access points. A literature review of various types of traffic control equipment was conducted, and one commercially available Driveway Assistance Device (DAD) was selected for further testing. The DAD is a portable device with arrows to show the permitted direction that a driver may turn. A test plan and protocol were developed to assess driver compliance and cost effectiveness. A simulated work zone was established for field testing using T-type intersections and including two test locations. Remote control capability of DAD equipment was tested with 11 volunteer drivers in November 2019 and January 2020 to evaluate the efficacy of the DAD equipment and assess various operational considerations.

Estimated costs of using the DAD equipment versus a human flagger at the low volume access point were compared. Costs were organized by three cases:

1. Case 1 (a human flagger): researchers assumed that there was one flagger or operator who required one communication radio, one stop paddle, and one set of safety equipment set (including a traffic vest, hat, etc.).
2. Case 2 (a DAD operating under local control or a dedicated operator): besides the DAD equipment, researchers assumed there would be one flagger/operator, one communication ratio, and one set of safety equipment.
3. Case 3 (a DAD remotely controlled by an existing flagger/operator): besides the DAD equipment, researchers assumed there would not be an additional flagger/operator, communication radio, stop paddle, or set of safety equipment.

When comparing the total costs of each of the three scenarios, the DAD equipment was assumed to be rented for one month, and utilized 50 percent of the time (e.g., for two weeks out of the month). The job was assumed to be active five days a week, resulting in a total of 10 working days. A setup / takedown fee would be incurred twice, once at the beginning and once at the end of the job. The median value of the range ($1,050) was used for the rental price for equipment. The values shown in Table 1 represent the estimated additional personnel, equipment, and costs for low volume access point control, which represent additional costs beyond costs already incurred for the main line traffic control.

Table 1. Summary of estimated additional costs for the three scenarios.