A Physics lesson with Collision Reconstructionist Cpl. Barry A. Red Iron

Collision Reconstructionist RCMP Corporal Barry Red Iron

Chris Davis

Collision Reconstructionist RCMP Corporal Barry Red Iron is a man who sees and analyzes lots of grim events.  Last week he took a break from that to educate some Matthew Halton School students, explaining and demonstrating how the application of physics enables him to come to some very specific conclusions about chaotic events.

"I am the Program Manager for UAVs (unmanned aerial vehicle) in Alberta, we have about ten of these, and they're about $20,000 a pop."


"It's a drone."

"Now we can fly directly over a crash scene and determine input angles, output angles, just by laying a protractor on the picture.  It's so fast, it's great."  The person running the drone must follow transport Canada flight rules, and have specialized training through flight school.

"In my profession, in what I do, I don't deal with people, all we deal with is physical evidence.  we're the CSI  of crashes," said Red Iron.

He talked about the physics used in accident investigation. The dangers of driving were evident as the undercurrent of so many of his experiences.  After a formal presentation in the classroom he took us outside to demonstrate some of the tools from his gadget laden SUV,  tools he uses to investigate accident scenes, up to and including airplane accidents.  He's got drones in there.

According to Red Iron the RCMP method determines what actually happened during an accident by using available information to calculate other factors.  Some of the factors that Red Iron discussed included gravity, force, speed, acceleration/deceleration, drag, coefficient, friction, weight, load, velocity, critical velocity, load, and increasing radius.

"You all know what a co-efficient is, right?  It's the friction between two sliding surfaces.  When you are talking about different compounds, there's obviously a drag factor associated."

"Factors that affect coefficient and friction include temperature, oil of grease, sand or gravel, rain, snow, and ice.  "That changes your coefficient and friction, so keep that in mind."

Examples were given to explain how to calculate the coefficient requires force, and weight. "When I have a motorcycle crash, and the guy goes sliding down the road, I know his weight, (determined at the hospital.)  "I will find someone of his weight, put them in a leather jacket, and I'll drag him.  Then I know what his coefficient is.  So, from the time he hit the ground, to the time he came to rest, I know how fast he was going."

Red Iron was explicit that the RCMP use minimum range when they aquire the calculation by use of a table. "We always give the benefit of the doubt for the people that we charge, always."

"When I go up there and you say 'Hey officer, I was only going 40k, I can go, hmmm, no."

"If you know the radius, what your gravity is, and the coefficient of friction is you can come up with the velocity speed for that measurement."

Cpl. Red Iron was pleased when students demonstrated their knowledge of various formulas that he used day-to-day.  He continued, explainining how grades or inclines can affect the scene of an accident.

Critical velocity of scuff marks

He explained the formula used to determine critical velocity from scuff marks.  "If you know the radius, what your gravity is, and what the coefficient of friction is, you can come up with the velocity speed for that measurement."

According to Red Iron the RCMP has five methods to determine the co-efficient of a vehicle:

• Drag - to drag a car or tires that were the same as those from a scene, rarely used.
• Drag slides - This is a commonly applied method that was demonstrated to us on the street outside.
• Shot marker testing - A 22 shell loaded with a marking compound is pointing down from the back of a vehicle. It is wired to the brake marking the exact point breaking starts.
• Accelerometer - he uses a Vericom 4000 daq.
• Tables and charts designed for accident scenes.  One tool that the RCMP use is a coefficient / friction table or chart form that was designed in 1954 that is in use and still very accurate.  "The only thing that it doesn't take into consideration is chip coating for us."

During the real-world demonstration he took a student for a spin on Kettles Street north of the school, accelerated, skidded to a stop, and then walked us through analyzing the scene.

Cpl. Red Iron and TJ measuring a skid with a drag slide

He can make surveyed information into 3D re-creations.  He demonstrated an airplane crash scene he'd created, a movie of the incident, after explaining the steps he took to make each determination.   "It's the second most northern town in the arctic."

How to determine the coefficient requires force and weight: 

"You all know what a co-efficient is, right?  It's the friction between two sliding surfaces.  When you are talking about different compounds, there's obviously a drag factor associated."

"When I have a motorcycle crash, and the guy goes sliding down the road, I know his weight, (determined at the hospital).  "I will find someone of his weight, put them in a leather jacket, and I'll drag him.  Then I know what his coefficient is.  So, from the time he hit the ground, to the time he came to rest, I know how fast he was going."

Along the way he touched on braking patterns and skid marks.

"I know that it's so much information, in such little time."

Where most systems round up, he rounds down.

When it comes to scenes that may result in charges he said "We always give the benefit of the doubt for the people that we charge, always."   He was reiterating a theme he touched on several times.

He explained how physics applies in the deployment of airbags.

He recommends relaxing if you're having an accident.

"If you learn something new, it's a great day," he said before he was on his way.