What is a safe following distance for a truck?

HGVs and trucks need extra space between vehicles for a safe braking distance. A safe braking distance is a distance where a HGV has time to brake and come to a stop short of hitting the vehicle in front, if that vehicle brakes suddenly.

We recommend the following distance for HGVs:

Driving under 40mph

If you are driving under 40mph, which you will be in urban areas, we recommend that you maintain 5 seconds between you and the vehicle in front (so, it will take you five seconds to clear a marker after the vehicle in front does. That equates to roughly 1 second per every 3-metres of your vehicle’s length (assuming your artic is 15m in length). 

Driving over 40mph

If you are driving over 40mph, which you will be on the motorway, you should add a second for every 3-metres of your vehicle’s length. So, a safe following distance would be 10 seconds between you and the vehicle in front. You should add time to this distance, if the roads are wet or icy because this will increase braking time. 

Motorway chevron markings

On some motorways, you will find chevron markings at 40-metre intervals. These are put there to help you calculate a safe following distance. Where chevron markings exist, it is recommended that you maintain a gap of two chevrons between you and the vehicle in front. This equals 80-metres, which is more than enough for a HGV. 

Lorry weight

It is important to also consider the weight of your lorry when maintaining a safe following distance. You can safely reduce the following distance if you are not towing a trailer, but you should increase the distance if you are. The heavier your HGV is, the bigger the gap between you and the vehicle in front should be. 

The 3 Second Rule

Another way to consider safe following distances is with the ‘Three Second Rule’, which stipulates that you should maintain a gap of 3 seconds between you and the vehicle in front. 

However, the 3 Second Rule contradicts our recommendations, because it requires that you maintain a shorter distance between you and the vehicle in front. In our opinion, 3 seconds is not enough time for a HGV to safely stop and especially so for fully-laden one. As such, we recommend that you maintain a 5 second rule at a minimum.