Quick answer
You were holding your lane on a dual carriageway, a motorway or a multi-lane road in town when the car alongside drifted or swerved into your lane and clipped you. Sideswipe collisions, where two vehicles travelling in the same direction make contact during a lane change or a merge, are common wherever lanes run side by side, and they are uniquely awkward to resolve because both drivers were moving and each will often claim the other was the one who strayed.
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Someone changed lanes into me: sideswipe and merging claims (UK)
You were holding your lane on a dual carriageway, a motorway or a multi-lane road in town when the car alongside drifted or swerved into your lane and clipped you. Sideswipe collisions, where two vehicles travelling in the same direction make contact during a lane change or a merge, are common wherever lanes run side by side, and they are uniquely awkward to resolve because both drivers were moving and each will often claim the other was the one who strayed.
This guide explains how fault is decided when someone changes lanes into you in the UK, the Highway Code rules that govern lane changes and merging, the evidence that shows who left their lane, and how the non-fault claim is handled - including recovery, repairs and a replacement vehicle at no upfront cost when you were not to blame.
The lane-changing driver's duty under the Highway Code
The Highway Code places the burden on the driver who wants to change lanes or merge to do so only when it is safe and will not force another driver to take action. Rule 133 tells drivers, when changing lanes, to give way to traffic already in the lane they are moving into and to use mirrors and signals so as not to cut across other vehicles. Rule 134 governs lane discipline in queues. The general mirror-signal-manoeuvre routine (rules 159 to 161) requires a driver to check mirrors, check the blind spot and signal before moving sideways, and to move only when it is safe.
On motorways, rule 268 prohibits unnecessary weaving between lanes, and the merging guidance expects drivers joining or moving across to fit into the existing flow without causing other traffic to brake or swerve. A driver who changes lanes into a vehicle that is already established in that lane has, by definition, failed to give way and failed to check the space was clear. That is why, where the evidence shows you were holding your lane and the other driver moved into you, liability normally rests with them.
DETAIL
Section 3 of the walkthrough.
Why sideswipe claims are often disputed
The core difficulty in a lane-change collision is that, from the outside, it can be hard to tell which vehicle crossed the line. The driver who changed lanes will frequently allege that you were the one who drifted into them. Because both cars were moving in the same direction, there is rarely the clear geometry that a junction or rear-end case provides. This is exactly why the physical evidence carries so much weight.
Insurers and engineers look closely at the point and angle of contact. Damage running along the side of your car, especially toward the rear, paired with front-corner or side damage on the other vehicle, tends to indicate that the other car moved into your established line. The pattern of paint transfer, scrape direction and the relative positions at impact all feed into the engineer's assessment of who strayed. Where neither side can prove the other crossed the line and there is no camera footage, insurers sometimes split liability, which is why preserving good evidence is so important.
The evidence that shows who left their lane
A dashcam is, once again, the most powerful single piece of evidence. Footage showing you holding a steady line within your lane while the other vehicle moves across into you usually settles the question. Preserve the clip immediately, since dashcams overwrite on a loop. Rear-facing dashcam footage can be just as useful as forward-facing in a sideswipe.
The damage profile on both vehicles - where along the side the contact runs, and the direction of the scrapes - which an engineer reads to work out who moved into whom.
Photographs of both cars in their resting positions before they are moved, showing how they ended up relative to the lane markings.
Paint transfer between the vehicles, which can corroborate the direction of the impact.
Independent witnesses travelling behind or alongside who saw which car changed lanes - their account is especially valuable when the two drivers disagree.
Motorway and dual-carriageway CCTV, and any nearby camera footage, which must be requested fast as retention is typically 14 to 31 days.
Merging, slip roads and motorway specifics
Merging cases have their own flavour. A driver joining a motorway or dual carriageway from a slip road must adjust speed to fit a gap in the existing traffic and give way to vehicles already on the carriageway; the through-traffic does not automatically have to make room. Where a merging driver forces their way across and clips you, the duty they breached is the duty to merge safely into an available gap.
Motorway sideswipes are also more dangerous than their town equivalents because of the speeds involved and the proximity of other fast-moving traffic. If a lane-change collision happens on a motorway, the first priority is safety: get the vehicles, if movable, to the hard shoulder or a refuge, put on hazard lights, and if you must leave the car, exit by the nearside and get behind the barrier before calling for help. Our motorway accident service, covering the particular recovery and safety issues of high-speed roads, is set out at /motorway-accident-claims.
What to do at the scene
Stop and check for injuries - section 170 of the Road Traffic Act 1988 requires you to stop after any accident involving injury or damage, and sideswipes at speed can cause more harm than the modest-looking damage suggests. Exchange details as section 170(2) requires: name, address, keeper's details if different, and registration, with the other driver's insurer where available. If the other driver leaves, refuses or gives false details, note the vehicle and report to the police within 24 hours under section 170(6).
Then lock down your evidence. Preserve any dashcam clip first, photograph both vehicles where they came to rest relative to the lane markings, capture the side damage and paint transfer on both cars, and get contact details from any witness who saw the lane change before they drive off. In a dispute about who strayed, this evidence is what tips the balance.
How the non-fault claim is handled
Once the evidence establishes that the other driver changed lanes into you, their insurer is responsible for restoring your position. If your car is undriveable, we arrange 24/7 recovery and secure storage. An independent engineer inspects the car to fix the proper repair scope and to record any pre-existing damage, and repairs are coordinated through a vetted bodyshop working to recognised standards (PAS 125 or BS 10125). The dedicated page on lane-change and sideswipe cases, at /lane-change-accident-claims, explains how these contested claims are proved and run.
Because the lane-changing driver is at fault, their insurer carries the cost of repairs, recovery, storage and a replacement vehicle, so your own policy and no-claims discount need not be touched. Where you need a car while yours is off the road, a like-for-like replacement can be arranged on credit hire, with the reasonable cost recovered from the at-fault insurer under the principles in Lagden v O'Connor [2003] UKHL 64 - which entitles a non-fault driver who cannot afford to hire otherwise to recover the cost of credit hire - and within the limits in Dimond v Lovell [2002] 1 AC 384, which requires the hire to be reasonable in rate and duration. Our credit hire service is explained at /credit-hire.
Time limits and why evidence cannot wait
Under section 2 of the Limitation Act 1980 you generally have six years from the date of the accident to claim for vehicle damage, and section 11 gives three years from the date of injury for personal injury. As with every contested claim, though, the evidence runs to a far shorter clock. Motorway and roadside CCTV is typically held for only 14 to 31 days, dashcam loops overwrite within hours, and witness memories of a fast lane change fade quickly. Opening the file straight away is the difference between a clean non-fault outcome and an avoidable 50/50 split.
Take action
If you have just been in a non-fault collision, the fastest way to protect your claim is to open the file with us inside the first hour. We dispatch recovery, lodge the relevant CCTV requests inside the retention window, and notify the third-party insurer for you.
