Expert Witness Journal Issue 66 April 2026 - Flipbook - Page 35
Case study 2: Occupant injury
and biomechanics
Guidance for lawyers and insurers
In a previous piece I wrote on this topic, I
recommended the TIP framework (Triage, Instruct,
Preserve) for those managing RTC claims in
insurance or legal contexts. This approach ensures
the data is considered and captured, whilst ensuring
costs are kept in check.
As discussed, it is not only fraud cases where this
data is invaluable. EDR evidence can also support a
more defensible discussion around injury causation.
It does not tell you how an occupant behaved during
a collision, but the data can be used to reconstruct
the forces of the collision and corroborate the injury
biomechanics.
Triage
As soon as possible after noti昀椀cation of a claim, try to
establish the make, model, and year of the vehicle(s)
involved. Where the vehicle was manufactured after
2024, there is a good chance the vehicle is supported
for download. Crash data may not necessarily have
been captured as this ultimately depends on the
severity of the collision, but that aspect can be
determined later. Ensure the vehicle is retained
whilst a decision is made on data recovery.
In this case, a claim was received regarding a
signi昀椀cant side impact on a major ‘A’ road. The
Claimant was a rear seat passenger of the vehicle
which was turning right across the dual carriageway.
During the turn, the vehicle was struck by an
oncoming vehicle at high speed. During the impact,
the passenger was thrown free from her seatbelt
and came to rest partially in the footwell, having
sustained a serious traumatic brain injury (TBI).
Instruct
Contrary to the previous case study, the EDR data
showed that the seatbelt status was ‘ON’ and that
the seat occupant sensor detected a person in the
seat at the time of the collision. Now, simply because
the data shows the seatbelt status was ‘ON’ does not
mean it was actually worn and/or worn correctly. For
this aspect, a physical examination of the seatbelt
was required to con昀椀rm whether the seatbelt had
been worn properly at the time of the collision.
One of the potential pitfalls with EDR data is that the
evidence is presented in an extremely user-friendly
manner (PDF 昀椀le), which means it is easy for the data
to be read and interpreted (potentially incorrectly)
by an unquali昀椀ed or inexperienced analyst. There
are many aspects that must be considered, and the
data has the potential to mislead if not interpreted
correctly. It is crucial that an appropriately quali昀椀ed
expert is instructed in cases that are likely to involve
EDR data. An early call to an EDR or vehicle-data
expert will also help determine if the vehicle is
supported and the likelihood of recovering crash
data. Following this, take immediate steps to
preserve the data. It may also be useful to consider
other forms of digital data that may be available
from the vehicle. EDR data is one aspect, but there
are other sources of digital data that may be available
and can be used to corroborate and complement
traditional collision reconstruction methods.
The EDR data also provided the ‘principal direction
of force’ experienced by the vehicle during the
collision and the subsequent change in velocity, or
‘delta-v’, which was used to determine the severity of
the ‘crash pulse’. Combined with forensic evidence
from the vehicle’s interior, which identi昀椀ed the
contact points from the Claimant’s head, we were
able to reconstruct the Claimant’s kinematics and
the likely magnitude of the force with which they
struck their head.
Preserve
This was a good example of how traditional
methods of collision investigation, such as vehicle
examination, can be used in conjunction with digital
evidence to support robust conclusions.
Clearly, storage costs can be signi昀椀cant, and there is
often a need to process the vehicle quickly to prevent
mounting costs. Thankfully, an early instruction
to remove the module, which is about the size of a
paperback book, means no delays in processing the
vehicle. The module can simply be removed and
stored for analysis at a later date, if and when a claim
progresses.
The bene昀椀t of having objective data to support
decisions around injury biomechanics and occupant
kinematics during a collision can prove vital. In
this case, it was used to determine that the seatbelt,
whilst likely worn, had been left with too much slack,
which allowed the occupant to come free in what is
often referred to as a ‘submarining’ incident. The
additional slack on the seatbelt meant the occupant
was not su昀케ciently restrained, and as such, the
Claimant’s head struck the interior of the vehicle
and they subsequently came free from the seat. This
evidence was also referenced heavily by the medical
expert witnesses in their assessment of the injury
mechanism and severity.
EXPERT WITNESS JOURNAL
None of these steps need to involve signi昀椀cant cost. If
detailed analysis is not justi昀椀ed, there does not need
to be further action, but having captured the data it
will prevent the scenario whereby a signi昀椀cant claim
is received after a vehicle has been disposed of.
About the authors
Craig Arnold is a Chartered Forensic Practitioner in
road collision investigation. Craig has given expert
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APRIL 2026
