The Crash Parameters Object

Crash Parameters contain computed crash analysis data for a vehicle, including delta-v (change in velocity) values calculated from damage photos or EDR data.

Object Structure

{
  "delta_v_min": 8.5,
  "delta_v_max": 12.3,
  "delta_v_method": "ml",
  "pdof_degrees": 180,
  "crash_pulse_min_ms": 12,
  "crash_pulse_max_ms": 100,
  "calculated_at": "2024-01-15T12:00:00Z"
}

Attributes

Attribute	Type	Description
delta_v_min	number	Delta-V at peak acceleration in mph
delta_v_max	number	Final maximum delta-V in mph
delta_v_method	string	Method used for calculation (see below)
pdof_degrees	number	Principal Direction of Force in degrees
crash_pulse_min_ms	number	Time at peak acceleration in milliseconds
crash_pulse_max_ms	number	Time at final maximum in milliseconds
calculated_at	string	ISO 8601 timestamp when values were calculated

Understanding Delta-V

Delta-V (ΔV) is the change in velocity experienced by a vehicle during a collision. It's a key metric for:

• Crash severity assessment: Higher delta-v indicates a more severe crash
• Biomechanics analysis: Used to calculate forces on occupants
• Expert reports: Standard metric in accident reconstruction

Delta-V Min vs Max

• delta_v_min: The delta-v at the moment of peak acceleration
• delta_v_max: The final maximum delta-v at the end of the crash pulse

In most crashes, delta_v_max is slightly higher than delta_v_min.

Calculation Methods

Method	Description
ml	Machine learning analysis of vehicle damage photos
edr	Event Data Recorder (EDR) data from vehicle black box
vector	Vector sum calculation combining multiple sources
hybrid	Combined ML and EDR analysis

Principal Direction of Force (PDOF)

The PDOF indicates the direction from which the primary crash force came, measured in degrees:

Degrees	Direction
0°	Front
90°	Right side
180°	Rear
270°	Left side

Null State

crash_parameters is null until delta-v calculation completes:

{
  "vehicles": [
    {
      "id": "veh_abc123",
      "role": "plaintiff",
      "crash_parameters": null  // Not yet calculated
    }
  ]
}

Calculation Triggers

Delta-v calculation is automatically triggered when:

1. Vehicle images uploaded: When damage photos are linked to a vehicle
2. Report creation: When creating a report with POST /api/reports
3. Manual analysis: Via the web UI

Example: Checking Crash Parameters

curl -X GET "https://api.silentwitness.ai/api/cases/case_abc123" \
  -H "X-API-Key: $API_KEY" \
  | jq '.data.case.vehicles[0].crash_parameters'

Response when calculated:

{
  "delta_v_min": 8.5,
  "delta_v_max": 12.3,
  "delta_v_method": "ml",
  "pdof_degrees": 180,
  "crash_pulse_min_ms": 12,
  "crash_pulse_max_ms": 100,
  "calculated_at": "2024-01-15T12:00:00Z"
}

Related Objects

• Vehicle - Parent object containing crash parameters
• Case - Root object containing vehicles