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SAE J2735-Draft-Rev18 [issued: 06-26-07]
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183 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
Annex A-2 Emergency Electronic Brake Lights
Application Description
When a vehicle brakes hard, the Emergency Electronic Brake light application sends a message to
following vehicles. This application will help the driver of following vehicles by giving an early
notification of lead vehicle braking hard even when the driver’s visibility is limited (e.g. a large truck
blocks the driver’s view, heavy fog, rain).
The current brake lamp goes on when the driver applies the brake. The Emergency Electronic Brake Light
application might not only enhance the range of a “hard” braking message but also might provide important
information such as acceleration/deceleration rate. At present, brake lamps do not differentiate level of
deceleration and are only useful as far rearward as line of sight allows.
Flow of Events
Flow of events
1. Vehicle “A” sends MSG_BasicSafetyMessageFrame, Part I
2. Vehicle “B” receives message
3. Vehicle “B” recognizes that Vehicle A’s message is relevant (similar heading
in advance of Vehicle B’s path) and a significant braking event is occurring per
the message information (e.g. deceleration, brake pressure).
4. Vehicle “B” alerts its driver to the braking event and provides some indication
of braking severity.
Hardware Devices:
DSRC radio
Positional Sensors
Human-Machine Interface
Occupant
Vehicle
System
Driver
Passenger
Service
Provider
Road
Department
Actors: (What entities
play an active role in
use)
X
X
Support information:
CAMP-VSC Task 3 Report, 2003
Concept of Operation
For this application, it is assumed that the vehicle in an emergency braking situation would be equipped
with a DSRC unit. It is also assumed that the message from the vehicle would be sent to the following
vehicles, including any that could have a collision with the braking vehicle but do not have single hop
communication with this vehicle.