Expert Witness Journal Issue 67 June/July 2026 - Flipbook - Page 60
Table 1 provides an overview of the data contained in each of the downloaded 昀椀les and on the Strava website.
Table 1 - Overview of the data contained in each of the downloaded 昀椀les and on the Strava website.
2. GPX Export
Moderate evidential value; useful for route
analysis, but limited in precision. A user may
also have access to more data when downloading
a GPX 昀椀le from their own Strava account than a
third party can access.
The case study highlights the importance of
providing experts with the most accurate data.
Whilst the provision of any data from the parties
involved in litigation is helpful, it is incumbent upon
experts to assess the best evidence obtainable.
It must be recognised that GPS devices are not
designed as collision sensors. While they can provide
substantial information about the circumstances
leading up to a collision, they cannot identify the
precise point or mechanics of impact in the way a
dedicated crash telematics device can. They often
record at a rate of 1 Hz (1 data point per second)
whereas devices designed for recording collision
data would record at much higher rates, potentially
as high as 100 hertz (100 data points per second)
or more. The positional accuracy of GPS data is
device-dependent and may be a昀昀ected by factors
such as dense tree cover, tall buildings, bridges,
tunnels or electrical interference. When used
alongside wider evidence relating to the collision,
such as photographs, scene marks, and post-impact
positions of the vehicles or persons involved, GPS
data can be interpreted in a balanced and reliable
way.
3. Website based Activity Display
Lowest evidential value; interpretative and not
always suitable for quantitative reconstruction,
although it may provide a more representative
indication of cyclist or runner speed than
reliance on published average-speed data alone.
Conclusion
The widespread use of Strava and similar platforms
has made GPS data increasingly accessible in collision
investigations. However, accessibility should not be
mistaken for evidential reliability.
The key distinction lies in data 昀椀delity:
•
•
•
Evidential Hierarchy in Practice
For robust collision reconstruction, reliance on the
original FIT 昀椀le is essential. Anything less introduces
uncertainty through smoothing, recalculation
or data loss, each of which may materially a昀昀ect
conclusions in both civil and criminal contexts.
When considered alongside the physical evidence
from the collision, the data can be used more
robustly.
From a forensic standpoint, GPS-related evidence
can be ranked as follows:
1. FIT (Original File)
Highest evidential value; a complete,
unprocessed dataset suitable for detailed
reconstruction. If the cycle computer or mobile
phone is available, data may be downloaded
directly rather than through an app.
EXPERT WITNESS JOURNAL
The Strava interface presents an interpreted
narrative
GPX exports provide a simpli昀椀ed dataset
FIT 昀椀les preserve the original recorded data
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JUNE 2026
