1. DSRC and SPaT, SSM, SRM & MAP
Co-operative ITS and SCATS
Updated
30/03/2015

2. Co-Operative Intelligent Transport Systems (C-ITS)
Co-Operative ITS
Emerging technology to enable vehicles and infrastructure to exchange information about location, speed, direction, status, etc.
Vehicle-to-Infrastructure (V2I)
Vehicles to Road Side Units communication (i.e. traffic controllers)
Receive traffic signal information based on vehicle’s position and direction of movement
Provide vehicle data (speed, direction, length) to RSUs to improve traffic management (i.e. queue detection)
Vehicle-to-Vehicle (V2V)
Improve vehicle “awareness”
Collision warning systems
Benefits:
Improve road safety and reduce congestion by aiding drivers in making better decisions when behind the wheel

3. C-ITS in Australia C-ITS continued…
Vehicles with built-in C-ITS: expected to arrive in 2015
CITI Project
First permanent test facility to evaluate benefits and risks associated with the technology
SCATS
Provide traffic signal information
Receive vehicle data as an input to be used in improving traffic management functionality
Red-light violation warning

4. Co-Operative Intelligent Transport Systems (C-ITS)
Theoretical C-ITS system view
VEHICLE INFRASTRUCTURE INTEGRATION (VII), CONCEPT OF OPERATIONS, US Dept of Transport Federal Highway Admin. Sep 2006, V1.2

5. DSRC, SPaT and Map Messages
Dedicated Short Range Communications
Designed specifically for automotive use
5.9 GHz Band (75Mhz spectrum US, EU uses 30MHz)
EU, USA and JAP systems are currently incompatible
SPaT – collection of four messages - SAE J2735 standard
SPaT: Signal Phase and Timing – provides the intersection’s signal light phases
MAP: Map Data – provides the physical geometry of the intersection
SRM: Signal Request Message – requests preempt or priority services
SSM: Signal Status Message – information about the internal state of the controller

6. Signal Phase and Timing (SPaT)
What is SPaT?
Intersection status message
Message data:
Intersection state
Movement state
Lane set - (i.e. lanes 9-10 are for movement state 1)
Current state - (Green, Yellow, Red, Flashing, Off)
Time until current signal state changes

7. Purpose of MAP message Message data Map Data (MAP)
Geometric layout of intersection
Message data
Reference point (intersection centre)
Number of approaches
Lane number
Lane width
Lane attributes
Straight, Left, Right, Turn on Red, Bus, etc...
Offsets
Points along each lane - used to detect vehicle position

8. Signal Request Message (SRM)
SPaT and Map messages – Intersection-to-Vehicle (I2V)
SRM – Vehicle-to-Intersection (V2I)
Priority signal request or a pre-emption signal request
Vehicle identifies itself using Vehicle Identification Number
Provides current position data (speed, heading, vehicle size, etc.)

9. Signal Status Message (SSM)
Signal Status Message – related to SRM
Provides current intersection status to all vehicles in range
Active and pending priority and pre-emption requests
Allows other users to see their ranking/position in queue for any requests made as well as view currently active requests
Message Data
Status of signal controller
Active priority requests
Source of priority (which vehicle sent request)
Active pre-emption requests
Source of pre-emption (which vehicle sent request)
SSM message dependent on current request status
If no active events, SSM message is not broadcasted

10. Basic Safety Message (BSM)
Purpose of BSM
Exchange safety data regarding vehicle state
V2I & V2V applications
Message data
Position (lat, long, elevation, accuracy)
Motion (speed, heading, wheel angle, acceleration)
Vehicle size
Vehicle status (lights, wipers, brakes, sensors, etc) 10

11. SCATS C-ITS Phase I Project
A trial to evaluate the SPaT and MAP messages
Aim: To display current traffic signal status in vehicles
Interface 1: TSC <-> DSRC radio provides data to form SPaT messages
Interface 2: Geometry Server <-> DSRC radio provides Map information
ITS Summit 2013:

12. SCATS C-ITS Phase I Project
ITS Summit 2013: 12

13. SCATS & the CITI Project
Cooperative ITS Initiative Project
Transport for NSW’s Centre for Road Safety
to provide the first permanent test facility for C-ITS
Heavy Vehicle Trial route:
Port Kembla to F6 Freeway
SCATS
Provide SPaT and MAP messages
Advanced Driver Warning system
Transport for NSW - Project Proposal Report for Hume Highway to Port Kembla Corridor, CITI project (under HVSPP Round 3), John Wall, 22/10/2012 Version 0.7.3

14. SCATS & the CITI Project continued…
Transmission of SPaT messages

15. SCATS C-ITS Phase II and beyond
Adaptive Traffic Signals challenge
Countdown can only be provided during the intergreen period
Only reliable green time that can be provided is minimum green interval, not sufficient for Advanced Driver Warning system
Investigate the impact on adaptive traffic management of allocating a guaranteed green time interval during which signal group cannot terminate
x secs
SG cannot
terminate
Exact signal timing known
Signal timing subject to change,
within max/min values

16. SCATS C-ITS Phase II and beyond
Vehicle-to-intersection communication
Signal Request Message
Pre-emption and Priority services (Ambulance, Fire, Police)
Basic Safety Message
Vehicle position, speed, type and length information could be used to implement queue detection 16

17. Truck signal change warning
Future Applications
Truck signal change warning
Driver warning of an impending traffic signal change such that deceleration can be planned in order to stop safely at the intersection
Transit vehicle signal priority
Traffic signal priority request from public transport vehicles
Emergency vehicle alerts
Vehicles are alerted to the presence of an emergency vehicle approaching the intersection, which is given traffic signal priority
Red light violation alert
A warning indication is provided to the driver that a red light violation is likely to occur

18. Questions?
QUESTIONS?