You work for a forensic engineering firm and specialize in the field of collision reconstruction. You’re hired to advise your plaintiff lawyer-client on a matter regarding a collision that occurred on a residential street (Marty Drive, Scarborough, Ont.), with a posted speed limit of 40 km/h. At the incident location, Marty Drive intersected with Doc Road, forming a T-type perpendicular configuration. At the date and time of the incident, the weather was cold, and the road was slippery from water accumulation. It was at that time when the vehicle in question was traveling on Marty Drive approaching a stop sign and Doc Road. The driver lost control on the slippery roadway and slid into a large tree on the property located at the end of the intersection. The impact occurred head-on and resulted in serious injuries to the front passenger, who is represented by your client.
The vehicle involved in the collision was a 2018 Dodge Challenger (weighing 1,852 kg). The tree did not sustain any remarkable damage. Your client wants to access the
driver’s insurance policy, as they believe the driver was responsible by traveling too fast for the conditions, even though the plaintiff wasn’t seat-belted.
Through the download of the vehicle’s event data recorder, you found that the vehicle experienced a change in velocity (DV) of 38 km/h due to impact, but you were not able to retrieve speed data. Surveillance footage from a nearby residence doorbell camera showed the collision taking place and that the vehicle’s brakes were engaged, and the tires locked up for 20 meters prior to impact, which was estimated from landmark locations.

(a) Your task is to determine how fast the Dodge was travelling at impact, how fast it was initially travelling (prior to braking and leaving skid marks), and if it was exceeding the speed limit prior to braking. You can assume that the roadway/tire coefficient of friction was 0.3, and the collision restitution was 0.1. (15 marks)
(b) Where did the driver of the Dodge need to initiate maximum braking (tire lockup) from the speed calculated above in order to come to a full stop at the stop sign, preventing the collision? (5 marks)