Heavy traffic and urban driving
Managing congestion, lane changes and interactions with vulnerable road users in an urban environment.
Updated 13 June 2026
The danger of heavy traffic
The main source of danger in heavy traffic is the high number of users present in the same place. Each has their own constraints and their own course. The driver must be patient, share the road and refrain from taking risks to gain a few seconds. Constantly changing lanes does not save time but considerably increases the risk of an accident.
In heavy traffic: stay in your lane, increase safety distances and do not weave between lanes. Patience is your best ally.
Driving in a queue of vehicles
When driving in a queue, increase your safety distances to be able to brake gradually if the traffic slows suddenly (the 'concertina effect'). Never enter an intersection unless you are certain you can cross it completely: being stuck in the middle of a junction obstructs all users on the cross roads and can create a complete blockage.
Never enter a pedestrian crossing or level crossing if the road is not clear on the other side. You risk being stuck in a very dangerous zone.
Hazard lights and traffic jams
When you reach a congested area, switch on your hazard lights to warn vehicles behind you of the significant slowdown ahead. However, once you are in the middle of the jam, there is no need to keep them on. Stay vigilant even during prolonged stops and continue to observe your surroundings.
Changing lanes safely
If a lane change is necessary (exit, fork), make multiple checks in the mirrors and blind spots. Make sure the vehicle behind you is not making the same manoeuvre. Ensure there is enough space in the target lane so you do not end up stuck at an angle between two lanes. Activate your indicator and wait for a gap to open.
Before changing lanes, systematically check that a two-wheeler is not filtering between the lanes. They are often difficult to see in the mirrors.
Pedestrians in town
In urban areas, pedestrians are everywhere: on pavements, behind street furniture, between parked vehicles. Children are particularly unpredictable as they can appear without warning. Be extra vigilant near schools, parks and bus stops. Remember that a pedestrian who has entered a pedestrian crossing always has priority. In rain, pedestrians run for shelter and may slip or cross without looking, further increasing the danger.
Two-wheelers in heavy traffic
Cyclists and motorcyclists slip through where a car cannot pass. They are often found between lanes of vehicles or on the right-hand edges of the road. Regularly check your mirrors and blind spots, especially before any change of direction or lane. Filtering by powered two-wheelers is a common occurrence, even though it is strictly regulated. Before opening your door when stopped, check that no two-wheeler is approaching from behind.
Buses, trams and lorries
Large vehicles block your view and prevent you from seeing signs, pedestrians or obstacles. Increase your safety distances with them as much as possible. A stationary bus or lorry can take up the entire width of a street or roundabout. The tram always has priority over all users, including pedestrians, and its braking distance is very long.
The tram always has priority, even in shared zones and pedestrian areas. Only cross the tracks when the lines are completely clear and the lights are off.
Roadworks
In the presence of roadworks, the speed is lowered and temporary signs (recognisable by their yellow colour) guide you. Slow down from the first signs, change lanes without waiting until the last moment, and increase your safety distances. Be alert to workers on the road and obey the traffic cones or temporary lights regulating passage.
When roadworks reduce the road to a single lane, passage may be managed by workers with batons (green to go, red to stop) or by temporary lights. With temporary lights, a steady amber or red means you must stop, whilst a flashing amber means you may proceed. Never enter without a signal, even if the lane appears clear: a vehicle may already be entering from the other end.
The safety of the workers depends directly on your behaviour. Slow down, move over when you pass a vehicle alongside them, and strictly obey the temporary signs.
Recap
- In heavy traffic: patience, stay in your lane, increase safety distances.
- Only enter a junction if you can cross it completely.
- Hazard lights: switch on when approaching a jam, switch off once inside it.
- Before any lane change: mirrors, blind spots, and check for two-wheelers.
- Pedestrians are unpredictable, especially children. Maximum vigilance near schools and bus stops.
- The tram always has priority, even in pedestrian zones. Very long braking distance.
- Buses and lorries block the view: increase distances and anticipate hidden pedestrians.
- Roadworks (yellow signs): slow down, change lanes early, respect the workers.
Test yourself
When should you switch on your hazard lights in the event of a traffic jam?
- ○Throughout the jam
- ○Only when you are completely stopped
- ✓When arriving at the congested area to warn those behind
- ○Never, hazard lights are not for that
Correct answer : When arriving at the congested area to warn those behind
Why is it inadvisable to weave between lanes in heavy traffic?
- ○It is prohibited by the Highway Code
- ✓It does not save time and increases the risk of an accident
- ○Other drivers will block your way
- ○It damages the tyres
Correct answer : It does not save time and increases the risk of an accident
Sources: Sécurité routière (securite-routiere.gouv.fr) and service-public.fr.