Dashcam Telemetry Analysis AASHTO Stopping Distance Inelastic Momentum Exchange

Dashcam Collision Kinematics & Highway Reconstruction Lab

Investigate highway center-line crossovers, perception-reaction delay, and two-vehicle momentum transfers. Simulate how passenger cars and commercial gravel haulers interact under variable approach speeds, road frictions, and steering drift.

Scenario Parameters

Investigation Presets

Drifting Vehicle Speed (Car) 58 mph

Approaching northbound passenger sedan crossing center line.

Heavy Vehicle Speed (Truck) 52 mph

Southbound commercial 3-axle truck hauling aggregate/gravel.

Truck Mass (Gross Wt.) 54,000 lbs

Passenger car fixed mass: 3,450 lbs. Ratio determines Delta-V severity.

Perception-Reaction Time (PRT) 1.50 s

AASHTO standard is 1.5s - 2.5s before active emergency braking begins.

Center Line Drift Angle 4.2 deg

Rate of lateral encroachment into oncoming lane (12 ft lane width).

Road Surface / Friction (μ)

Evasive Steering Maneuver

Analyzing approach corridor...

REC ● HD 60FPS
TIME: 0.00s | SEPARATION: 280 ft

CLOSING SPEED: 110 MPH (161 FT/S)

T = 0.0s (Drift Starts) Impact Est: 1.74s T = 3.5s (Resolution)

Combined Closing Speed

110 mph

161.3 ft/s approach rate

Stopping Sight Distance

312 ft

Total reaction + braking

Drifting Car Delta-V

-48.2 mph

Estimated impact pulse

Heavy Truck Delta-V

-3.1 mph

Mass ratio: 15.6 : 1

Physical Reconstruction: At 110 mph combined closure (161 ft/s), a center-line intrusion leaves less than 1.8 seconds of reaction runway. When the 3,450 lb sedan impacts the 54,000 lb gravel truck, conservation of linear momentum distributes over 94% of velocity change (ΔV) into the lighter passenger vehicle.

Ready for investigation analysis. Scrub timeline or press play.

1. Stopping Sight Distance (AASHTO Kinematics)

Highway stopping sight distance combines perception-reaction distance and physical skid deceleration:

SSD = 1.47 × V × t_pr + (V²) / (30 × μ)

At 55 mph on dry pavement (μ = 0.75) with a standard 1.5s PRT, a vehicle covers 121 ft while the driver decides, plus 134 ft of lockup skid distance: 255 ft total. When two opposing vehicles approach each other, mutual stopping distance doubles to over 500 ft.

2. Heavy Truck Momentum Dissymmetry (ΔV)

In a collision between an oncoming passenger sedan (m₁ ≈ 3,450 lbs) and a commercial aggregate hauler (m₂ ≈ 54,000 lbs), momentum is conserved:

ΔV_car = (m₂ / (m₁ + m₂)) × (V_car + V_truck)

Because the gravel truck has ~15× the mass of the car, the car absorbs virtually all velocity change instantaneously (ΔV > 45 mph), generating severe crush deformation and violent deceleration, while the gravel truck slows by merely 3-4 mph.