“Where does it state in your manuals that frozen instruments are part of collision evidence?” Ah – it
Other matters came to a head and the case was thrown out.
I was frustrated, as I knew the instruments were giving a true picture of what the car was doing in this case,
but it was also true that the unwritten observations handed down by the preceding generation about
frozen speedometers were completely without any scientific basis. It was indeed folklore. A little internet
searching confirmed that little work had ever been conducted on what we were regularly finding at crash
A few months after this I happened to be speaking to an engineer who worked for an automotive supplier
who made speedometers. The topic soon turned to frozen instruments after a crash. They had never heard
of the problem but he knew a man, who may know a man, who may know. A few phone calls later and I
was introduced to a car instrument supplier who were willing to speak to the police about how their
products work. The only problem was the automotive industry has global suppliers and this company was
based in Switzerland.
Any hope of getting the police to fund a trip to Switzerland to research a problem that didn’t have a specific
prosecution case was a non-starter. The police did not have a forensic research budget for anything, let
alone collisions. However, this opportunity was too good to miss and my inquisitiveness was worth a £50
The automotive company were equally intrigued by what I said I was finding at crash scenes. They flew
their experts in from across Europe to join our meeting on the border of Liechtenstein. They were amazed
with what I showed them. They had not seen what happens to their products after a crash and confirmed
we were onto something. The key point, was that electrical power has to be lost during the crash. Once
they knew this, they thought about engineering a switch so that when a car crashes it automatically holds
the instruments at the reading upon impact. This was akin to a gun manufacturer changing their design to
assist a forensic ballistic expert!
This was just the start however. We now knew how and why the instruments froze during a crash. Next, I
needed to show if they could move about whilst being knocked around from the forces of the crash. I asked
if I could have access to some cars that were being crashed as part of a test day. I created a frame and
fitted as many instruments as I could (about 12) to a car about to crashed into another at high speed. It was
all a bit ‘Heath Robinson’ but it worked. We were crashing cars at speeds up to 75mph.
The testing involved making
a frame holding 12 different
types of instrument which
were fitted into the
passenger seat area of a car.
All the dials were set at
known positions before the
crash test and then checked
afterwards for movement.