Skip to main content

Pedestrian Hood Areas

Overview​

The pedestrian hood metric refers to a newly developed performance standard, FMVSS No. 228: Pedestrian Head Protection [1], built upon the Global Technical Regulation No. 9 (GTR 9) [2] and adapted to US conditions. This performance standard evaluates how well a vehicle's hood is built to reduce the severity of head injury to pedestrians during a collision with simulated head impacts using child and adult headforms [1]. The vehicle hood is split in 6 relevant areas (Hood Top, Hood Area, HIC Unlimited Area, Child Headform Test Area, Adult Headform Test Area, and Test Area) that are used to map the hood surface and evaluate the simulated head impacts (see Figures 1 and 2) [1].

Loadcell_sideLoadcell_front
Figure 1: Vehicle's Hood Top
Figure 2: Vehicle's HIC Unlimited Area, Child Headform Test Area, and Adult Headform Test Area

Figures 1 and 2 were taken from FMVSS No. 228: Pedestrian Head Protection [1]

Inputs​

  • Vehicle's Hood Top geometry

Calculations​

  1. Creates Hood Top
  • Front Boundary: Leading Edge Reference Line (LERL)
  • Driver Side Boundary: Driver Side Reference Line (SRL)
  • Passenger Side Boundary: Passenger Side Reference Line (SRL)
  • Rear Boundary: Rear Reference Line (RRL)
  1. Creates Hood Area
  • Front Boundary: WAD1000 or LERL (whichever most rearward)
  • Driver Side Boundary: Driver Offset SRL
  • Passenger Side Boundary: Passenger Offset SRL
  • Rear Boundary: WAD2100 or RRL (whichever most forward)
  1. Creates HIC Unlimited Area
  • The area between the Hood Top and the 82.5 mm offset around the entire perimeter of the Hood Top
  1. Creates Child Headform Test Area
  • Front Boundary: WAD1000 or Offset LERL (whichever most rearward)
  • Driver Side Boundary: Driver Offset SRL
  • Passenger Side Boundary: Passenger Offset SRL
  • Rear Boundary: WAD1700 or Offset RRL (whichever most forward)
  1. Creates Adult Headform Test Area
  • Front Boundary: WAD1700
  • Driver Side Boundary: Driver Offset SRL
  • Passenger Side Boundary: Passenger Offset SRL
  • Rear Boundary: WAD2100 or Offset RRL (whichever most forward)
  1. Creates Test Area by combining the Child and Adult Headform Test Area
  • A combination of the Child and Adult Headform Test Area
    • *If there is no Adult Headform Test Area, the Test Area just includes the Child Headform Test Area
  1. Uses shoelace formula to calculate the area for each of the 6 areas created in steps 1 through 6
A=12∣∑i=1n(xiyi+1−xi+1yi)∣A = \frac{1}{2} \left| \sum_{i=1}^{n} (x_i y_{i+1} - x_{i+1} y_i) \right|

Generated Figure​

Resultant Intrusion Bar Chart

Figure 3: Pedestrian Hood figure with relevant areas, WAD lines, and impact points

References​

[1] National Highway Traffic Safety Administration. Federal Motor Vehicle Safety Standards; Pedestrian Head Protection, Global Technical Regulation No. 9; Incorporation by Reference. U.S. Department of Transportation, 20 Nov. 2024.

[2] United Nations Economic Commission for Europe. Global Technical Regulation No. 9: Pedestrian Safety. United Nations, 2009.