 |
 |
 |
 |
|
 |
 |
SAE J2735-Draft-Rev29 [issued: 12-11-08]
-
280 -
This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
operator. The warning can advise the driver to be prepared to take actions to stay out of the path of the
responding vehicle. The warning could include information about:
The type of emergency vehicle
The location or proximity of the emergency vehicle
Instructions on action that the driver may want to take
The warning presented to the driver may be different depending upon the proximity of the emergency
vehicle to their vehicle. The closer the emergency vehicle is, the more severe the warning. If pre
determined emergency route information is available from a public safety vehicle, the information may be
sent via other applications.
In general, private vehicles are expected to ignore signal request and signal status messages. When a
preemption or priority event does occur in an intersection, they are informed of this by way of the
SPAT[RS47] message.
Other emergency vehicles that are responding, receiving the Emergency Vehicle Approaching message,
may use the data to analyze if they may encounter the responding vehicle. The warning can advise the
driver to be prepared to take actions to stay out of the path of the responding vehicle. The warning includes
information about:
The type of emergency vehicle
The location or proximity of the emergency vehicle
Instructions on action that the driver may want to take
The warning presented to the drivers may vary depending upon the proximity of other emergency vehicle
to their vehicle and the use of sirens by one or more responding vehicles. The closer the emergency vehicle
is, the more severe the warning that will be communicated to the operator.
In general, other emergency vehicles may also be sending signal requests and receiving signal status
messages at the same time (often in ad hoc convoys proceeding through the same intersection). The signal
state message may list their own signal requests as pending when another vehicle (ideally one ahead of
them) has been granted the preemption or priority first. When a preemption or priority event is occurring in
an intersection, they are also informed of this by way of the SPAT message, like private vehicles.
5. Application use with DSRC
The messages in this application are typically transmitted using the BER-DER encoding and the Wave
Short Message protocol (WSM) stack in a periodic broadcast mode on a high power channel (CCH or
SCH) to other devices (typically other mobile OBUs) who have determined to receive this type of message
(based on PSID value and running a suitable application). Upon reception of such messages they are
examined for message content and relevance regardless of any PSC provided by the sender.
If the message content is considered to be of a “low priority”
19
(such as standing static reports, permanent
school zones, and other semi permanent data such as construction warnings) then the message may be
transmitted using an XML encoding as an IP datagram over a service channel in a periodic broadcast mode
to other devices (typically other mobile OBUs) who have determined to receive this type of message (based
on PSID value and running a suitable application). Upon reception of such messages they are examined for
message content and relevance.
19
The ultimate determination of this classification, and therefore the encoding and bandwidth
allocated to either type of message is a local jurisdictional consideration.