Emergency Brake Display for Rear End Accident Avoidance

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Emergency Brake Display forRear End Accident
Avoidance

• Dr. J. Gail
• Ressort Active Vehicle Safety, Emissions,
  Energy
• Bundesanstalt für Staßenwesen
• (Federal Highway Research Institute)
• Bergisch Gladbach, Germany

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Content

• requirements for an emergency brake display
• examples
• optimum solution
• criteria for activation / deactivation
• regulations concerned

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Requirements for anEmergency Brake Display (1)

• fast perception (also by distracted drivers)
• short reaction times
• easy implementation and refitting
• maximum deceleration of the following car
• intuitive display (no learning necessary)
• few levels

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Requirements for anEmergency Brake Display (2)

• threshold values corresponding to real braking
  behaviour
• functionality for emergency braking on
  low-µ-surfaces
• unambiguous display
• not confusing
• minimised effects of habituation

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Example 1 Increased Light Surface Area and
Intensity
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Increased Area and Intensity

• pros
• intuitively
• no learning process
• causes adequate brakings of the following driver
  (early maximum brake force)
• reduced reaction times
• cons
• lights have to be fixed by the drivers eyes
• difficult refitting
• vehicle design

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Example 2 Integral Brakelight
3rd upper brakelight
G
(? 19 levels)
? too many levels
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Example 3 Flashing Brakelights
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Flashing Brakelights
reduction in reaction time (source
DaimlerChrysler)
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Flashing Brakelights

• pros
• good perception also by distracted drivers
• reduced reaction times
• easy refitting
• cons
• learning process might be necessary

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Example 4 Flashing Hazard Warning Lights
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Flashing Hazard Warning Lights
reduction in reaction time (source
DaimlerChrysler)
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Flashing Hazard Warning Lights

• pros
• good perception
• reduced reaction times
• easy refitting
• cons
• change in colour
• usual meaning warning in case of
• broken down vehicle
• accident
• end of congestion
• automatical switching only if
  deceleration gt 1.5 g

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Example 5 Continuously Shining Rear
Direction-Indicators

• pros
• easy refitting
• cons
• change in colour
• meaning is not intuitively clear

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Optimum Solution (1)

• keeping the colour coding red
  light braking
• flashing to achieve best perception by distracted
  drivers

(3 Hz to 5 Hz flashing)
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Optimum Solution (2)

• optional increase in surface area of lower
  brakelights additional to flashing upper
  brakelight

1)
2)
(3 Hz - 5 Hz)
? best perception intuitive display for
severe braking
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Criteria for Activation / Deactivation (1)

• threshold deceleration 7 m / s2
• emergency brake assistance system
• anti-lock brake system
• pressure of the brake system / brake force
• change of vehicle velocity (real deceleration)

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Criteria for Activation / Deactivation (2)

• switching on immediately after detection of
  emergency braking
• switching off after
• releasing the brake pedal or
• after standstill of the vehicle or
• detection of the end of the severe braking by a
  brake assistance / anti-lock braking system
• threshold velocity 5 km / h

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Regulations Concerned

• ECE-R 7, ECE-R 48 and Vienna Convention
• red flashing upper brakelight
• increase in surface area
• definition of activation of brakelights
• changing display during braking
• fixing of switching criteria