One-way roads and roundabouts: avoid direction mistakes

Direction errors are often avoidable if you check the restriction before you commit to the road.

Published 10 August 20263 min readPCO Topography Editorial Team

Read direction before distance

A short road is useless if it carries you in the wrong direction. When a compact side-street route looks attractive, check direction first and distance second.

Treat the junction as a movement

Do not only ask whether Road A touches Road B. Ask whether a vehicle can make the movement you intend at that point. Direction, central reservations and road layout can change the answer.

Roundabouts are roads, not empty circles

Plot around the carriageway rather than drawing directly across the middle of a roundabout. The route line should show the approach, circulation and exit clearly enough that the intended movement is unambiguous.

Divided roads need extra attention

A road shown as two carriageways may restrict where you can turn or cross. Before using a junction in the middle of a divided road, make sure the movement is physically and legally plausible on the map.

A useful practice drill

Choose a dense central-London area and plan several short journeys using different start points. The goal is not to memorise the streets; it is to make one-way checking automatic before every turn.

Use direction as a gate

Before you evaluate whether a road is convenient, make direction a yes-or-no gate. If the road does not support your intended movement, stop considering it immediately. This reduces the mental load because you are no longer comparing routes that are not genuinely available.

In dense areas, it can help to trace the next two movements mentally before plotting the first. A road may be legal to enter but leave you with no sensible legal exit toward FINISH.

Roundabout exits need to be deliberate

On a roundabout, identify the approach road and the intended exit before you start drawing around the circle. If you only follow the shape visually, it is easy to leave at the wrong arm. Keep the destination direction in mind as you circulate.

Central reservations change turns

A divided road can make an apparently simple right turn impossible at a particular point. Look for the physical break or junction that allows the movement. If the route requires crossing the reservation, make sure the map actually shows a usable connection.

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