One-Way Systems on Site

A one-way traffic system directs all vehicles around the site in a single direction, eliminating head-on and crossing conflicts.
One-way systems are one of the most effective measures for reducing vehicle-related incidents on construction sites.
The system must include clear signage at the entrance, along the route, and at every junction showing the direction of travel.
Turning areas must be designed into the route so vehicles can complete the circuit without reversing at dead ends.
Pedestrian crossings must be positioned at designated points with clear sightlines for both drivers and pedestrians.
The route must be wide enough for the largest vehicle using it, with allowance for tracking on bends and corners.
Speed limits must be set and signed for the route — speeds should reflect the road surface, gradients, and visibility.
The one-way system must be communicated to every driver during the site induction before they proceed past the gate.
Changes to the route due to construction progress must be clearly signed and communicated before they take effect.
Regular monitoring confirms drivers are following the system — non-compliance must be challenged immediately.

Eliminate head-on	Head-on collisions between site vehicles cause fatal injuries — a one-way system removes this conflict entirely.
Reduce reversing	A circuit route with turning areas eliminates the need for reversing, which causes the majority of struck-by deaths on site.
Simple and effective	One-way systems require only signs and route design — they are cheap to implement and dramatically reduce vehicle risk.

Do

Don't

Design the one-way route with adequate width for the largest vehicles using it.
Install clear directional signage at the entrance, junctions, and along the route.
Include turning areas so vehicles complete the circuit without needing to reverse.
Provide designated pedestrian crossings with clear sightlines at controlled points.
Set and sign speed limits appropriate to the route surface and conditions.
Brief all drivers on the one-way system during the site induction.
Update signage and communicate route changes before they take effect.
Monitor driver compliance and challenge anyone driving against the flow.
Maintain the road surface along the one-way route throughout the project.
Review the route as the site layout changes to ensure it remains workable.

DON'T allow two-way traffic when a one-way system is practicable for the site.
DON'T operate without clear directional signs at every decision point on the route.
DON'T create dead ends that force vehicles to reverse on the one-way circuit.
DON'T allow pedestrians to walk along vehicle routes without designated crossings.
DON'T omit speed limits — uncontrolled speed on site routes causes serious incidents.
DON'T let drivers onto the site without briefing them on the one-way system.
DON'T change the route without updating signage and telling all drivers first.
DON'T tolerate drivers ignoring the one-way system — challenge non-compliance instantly.
DON'T let the route surface deteriorate — maintain it for safe vehicle movement.
DON'T keep the same route design when the site layout has changed significantly.

See also: Site Speed Limits and Route Planning | Pedestrian and Vehicle Segregation

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