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SAE J2735-Draft-Rev29 [issued: 12-11-08]
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This is an SAE Motor Vehicle Council draft document of the DSRC committee, subject to change.
3.54 Node Configuration data: Definition to be refined by committee. When a map of an intersections is
represented a node configuration data value provided key information regarding how the data vales found
in the map are to be understood.
3.55 notification: An indication of an event of interest, sent to an application.
3.56 OBU to vehicle host interface (OVHI): Interface on the OBU offering access to WAVE capabilities
by other vehicle-based devices.
3.57 offset (phase): Offset is the time lag for the cycle start of a coordinated signal. Quoting from the
FHWA Signal Timing Manual, Chapter 6, Section 6.1 Terminology. (Draft 3 version, development still
underway): “The time relationship between coordinated phases defined reference point and a defined
master reference (master clock or sync pulse)." In other words, a local signal controller setting that
references the start of the green to a common clock so the beginning of green can be coordinated along a
roadway to speed motorist along at a designed speed.
3.58 on-board unit: An On-Board Unit (OBU) is a vehicle mounted DSRC device used to transmit and
receive a variety of message traffic to and from other DSRC devices (other OBUs and RSUs). Among the
message types and applications supported by this process are vehicle safety messages, a primary subject of
this standard, used to exchange information on each vehicle's dynamic movements for coordination and
safety.
3.59 operations: One of three modes, or states, of operation known as Registration, Initialization, and
Operations which DSRC systems operate in. In the Operations mode a link has been established, the link
will have an open socket with which it can conduct operations in the same manner as with any other 802.11
communications session. The lower layers will be managing the switching between the Control Channel
and the Service Channel. When the radio has switched to another channel, it would appear to the
application as a temporary loss of communications.
3.60 pedestrian change interval: An interval during which the flashing UPRAISED HAND (symbolizing
DONT WALK) signal indication is displayed, often also called the pedestrian clearance time. During this
interval the SPAT messages indicates a don’t walk state for that pedestrian lane (along with an optional
period of time remaining for this state).
3.61 pedestrian clearance time: The minimum time provided for a pedestrian crossing in a crosswalk,
after leaving the curb or shoulder, to travel to the far side of the traveled way or to a median. During this
interval the SPAT messages indicates a Flashing Don’t Walk indication for that pedestrian lane (along with
an optional period of time remaining for this state). The duration for such time intervals comes from
MUTCD and is based on a rate of speed of 2 meters per second.
3.62 pedestrian phase: The time during which a walking figure or word “WALK” is presented and the
DON’T WALK is presented. The pedestrian phase is also the time interval of the pedestrian walk interval
and the pedestrian change interval combined.
3.63 pedestrian walk interval: An interval during which the WALKING PERSON (symbolizing WALK)
signal indication is displayed. When a verbal message is provided at an accessible pedestrian signal, the
verbal message is “walk sign.” During this interval the SPAT messages indicates a walk state for that
pedestrian lane (along with an optional period of time remaining for this state and the subsequent
pedestrian clearance state).