How Driveway Assistance Devices Keep Side Roads and Businesses Safe Inside Signal-Controlled Work Zones
Road construction can make it difficult for people to enter or leave homes, businesses, and side roads. When one lane is closed, temporary traffic signals control alternating traffic through the remaining lane. However, drivers entering from driveways or side roads in the middle of the work zone may not be able to see those signals. Without clear guidance, they could turn into the path of oncoming traffic.
Driveway assistance devices help address this problem by showing drivers when to wait and which direction they may travel. These devices work with temporary traffic signals to reduce the risk of conflicting traffic movements while maintaining access to property during construction.
What are driveway assistance devices?
A Driveway Assistance Device (DAD) is a specialized traffic control unit that guides vehicles entering a one-lane, bidirectional work zone from a driveway or another suitable access point.
The device uses illuminated directional arrows and red signal indications to guide motorists. It coordinates with temporary traffic signals at either end of the work zone, allowing vehicles to join traffic moving in the permitted direction without requiring a separate signal phase for each driveway.
Why side roads and business entrances need special attention in work zones
Temporary traffic signals are typically placed at both ends of a single-lane work zone. However, drivers entering from points between those signals need additional guidance because they must merge with traffic already moving through the work zone.
These access points can present several challenges:
Wrong-way entry: Drivers may turn into the path of oncoming traffic, increasing the risk of head-on collisions.
Unclear traffic direction: Motorists may struggle to determine when they can enter the roadway and which direction they should travel.
Restricted access: Construction barriers, lane closures, and equipment can make it harder for residents, customers, and employees to enter or leave properties.
Increased traffic delays: Installing separate temporary signals at each access point may require additional signal phases, resulting in longer waiting times for vehicles traveling through the work zone.
How driveway assistance devices control traffic at access points
DADs coordinate vehicles entering from driveways with traffic moving through the work zone. They do this through three main functions.
Coordinating with temporary traffic signals
DADs communicate wirelessly with temporary traffic signals positioned at both ends of the work zone. As the permitted direction of traffic changes, the devices update their signal indications in coordination with the main signals.
This allows traffic at individual access points to be managed without requiring a separate signal phase for each driveway.
Using red signals and flashing directional arrows
DADs display different signal indications to tell drivers when to wait and which direction they may travel.
A steady red indication instructs drivers to stop and wait, while a flashing directional arrow indicates the permitted direction of travel.
Allowing vehicles to join the permitted traffic flow
When the appropriate directional arrow is displayed, drivers may enter the open lane after stopping and yielding as required.
This allows vehicles leaving driveways to join traffic moving in the permitted direction, helping reduce confusion, prevent conflicting traffic movements, and avoid unnecessary interruptions to the mainline signal sequence.
Key safety benefits of driveway assistance devices
DADs give drivers clear, coordinated instructions at access points throughout a work zone.
Their main safety benefits include:
Reducing wrong-way movements: Directional arrows help prevent drivers from turning against the current flow of traffic.
Improving driver compliance: Clear indications help motorists understand and follow the instructions for entering the roadway.
Reducing potential vehicle conflicts: Coordinated access helps limit situations where entering vehicles could meet traffic traveling in the opposite direction.
Managing multiple access points: Several devices can work together to provide consistent guidance at different driveways.
Monitoring signal conflicts: Some DADs use built-in dual-processor monitoring to detect conflicting signal indications and automatically place the system into a safe state.
A 2023 study found that 80% of drivers followed the signals displayed by DADs, compared with 22.7% who followed traditional temporary traffic signals at driveways. These findings suggest that DADs can improve driver compliance and help reduce unsafe traffic movements within work zones.
How driveway assistance devices help reduce traffic delays
Traditional temporary traffic signals at individual driveways may require mainline traffic to stop while vehicles from those access points enter the roadway. When several driveways have separate signal phases, waiting times and queues can increase.
DADs reduce these interruptions by letting vehicles from driveways join traffic moving in the permitted direction without adding separate signal phases.
The same 2023 study found that DADs reduced driveway waiting times by 46% and mainline traffic queue lengths by 32% compared with traditional temporary traffic signals.
These improvements help maintain smoother traffic flow through work zones while reducing delays for drivers accessing properties along the affected road.
What should be considered before installing DADs?
Before installing a driveway traffic control system, it is important to check whether the devices are suitable for the work zone's traffic conditions and roadway layout.
Key factors to consider include:
Traffic volume: DADs may be suitable for access points handling around 30 to 50 vehicles per hour, depending on site conditions. Locations with heavier traffic require further evaluation before installation.
Roadway layout: Sharp curves and poor visibility can make it harder for drivers to see approaching traffic and enter safely.
Signal coordination: DADs must be properly connected and coordinated with the temporary traffic signals controlling the work zone.
Driveway layout: Drivers need enough space to stop, wait for the appropriate signal, and enter the roadway.
Traffic control requirements: Installation must follow applicable traffic control standards and any required approval procedures.
DADs are primarily designed for residential driveways, but they may also be considered for suitable low-volume business entrances and side roads after reviewing local traffic conditions and access requirements.
Improve work zone access and safety with Right Traffic
Managing driveway access during construction helps reduce the risk of conflicting vehicle movements while maintaining efficient traffic flow through single-lane work zones. DADs provide clear guidance to drivers entering the roadway while minimizing unnecessary interruptions to mainline traffic.
Right Traffic offers a range of traffic control products for sale, including the Horizon Signal Driveway Assistance Device. Contact the team to learn more about product specifications, availability, and suitability for your work zone project.
Frequently asked questions
Why are driveway assistance devices used in work zones?
DADs guide vehicles entering single-lane work zones from driveways and other suitable access points. They indicate when drivers must wait and which direction they may travel.
Do driveway assistance devices help reduce traffic congestion?
Yes. They can reduce delays and queues by letting driveway traffic join the permitted flow without a separate signal phase. The benefits depend on traffic volume, signal timing, and site conditions.
What types of work zones are suitable for driveway assistance devices?
They are primarily designed for one-lane, bidirectional work zones with residential driveway access. Other low-volume access points may be suitable following a traffic assessment.
Are driveway assistance devices used with temporary traffic signals?
Yes. DADs communicate wirelessly with temporary traffic signals and update their indications according to the current signal sequence.
Can driveway assistance devices be installed at business entrances?
They may be suitable for certain low-volume commercial driveways. Higher-volume entrances require further evaluation to determine whether DADs can manage traffic effectively.
Can multiple driveway assistance devices operate within the same work zone?
Yes. Multiple DADs can operate as part of a coordinated system, with a unit at each designated access point.