Use Cases

The first step in developing the Concept of Operations will be to determine appropriate use cases for both the longer-term testbed and, of more immediate consequence, for the World Congress milestone.

Longer-term use cases will be drawn from those briefly described below:

1. Vehicles as Traffic Probes – The vehicles shall send raw location, time, speed and direction information to roadside units (RSU) which will pass the raw data along to a central processing center where it will be used to create timely and accurate real-time traveler information. The central processing center would be the 511/TravInfo™ system. The traveler information shall be disseminated to the Caltrans District 4 TMC and to the public via the 511/TravInfo™ system.
2. Intelligent On-Ramp Metering – This application involves using wireless-equipped vehicles to measure real-time traffic density on the highway so that on-ramp signal phasing can be dynamically adjusted to maximize mainline traffic flow.
3. Vehicle Probes Provide Weather Data – The vehicles provide location and
   direction information, along with the status of on-board sensors (temperature, precipitation, sun, level, traction control, etc.) and the status of on-board devices (headlights, wipers, heater, air conditioner, etc.) to the central processing center so it can determine the real-time weather conditions on the roadway.
4. Travel Time Data to Vehicles – The central processing center sends accurate and up-to-date link travel times to the RSU and then the vehicle for use in real-time dynamic routing. The travel times will be generated by the 511/TravInfo™ system.
5. Incident Information to Vehicles - The central processing center transmits real-time incident information to the RSU and then the vehicle, which can be programmed to present this information to the driver in accordance with installed equipment and selected options. The incident information will originate from the 511/TravInfo™ system.
6. In-Vehicle Signage – In-vehicle signing refers to the display (and annunciation, where necessary) of available roadside sign information inside the vehicle. This information would be transmitted via RSUs. The information can describe features about the local area such as speed limits or services that are provided in the near vicinity.
7. Work Zone Safety Warning - Work zone safety warning refers to the detection of a vehicle in an active work zone area and the indication of a warning to its driver. RSUs would broadcast the warning data to vehicles as they approach a work zone or construction zone.
8. Intersection Collision Warning – This is the application of safety critical messaging between vehicles and roadside equipment for cooperative intersection safety, focused on signal violation and left-turn crashes. Such an application would likely require low latency communications concepts such as the 5.9 GHz-dedicated short-range communications (DSRC). This potential use case differs from the others because the implementation envisioned under VII California may be prototypical.
9. Curve Overspeed Warning – Another application of low latency safety critical messaging would be curve overspeed warning, wherein road curvature (and potentially, road surface condition) would be broadcast to vehicles, and vehicles would combine this information with their dynamic state to provide in-vehicle warning and, as desired, correction. An extension would be that vehicles that issue curve overspeed alerts would transmit such information to the roadside, enacting a general warning to unequipped vehicles.

It is possible that some of the use cases above may be combined into a single application, e.g., in-vehicle signage may also include work zone warnings or incident information. Moreover, the above list may be refined as more input is received from car manufacturer stakeholders.

Through VII California Working Group meetings, six use cases have been selected for the VII deployment aimed at the World Congress milestone. The six demonstrated use cases are a subset of the above, namely:

1. Vehicles as Traffic Probes – Data from vehicles is sent to the central processing center and used to calculate travel times along specified links, routes or paths.
2. Travel Time Data to Vehicles – The central processing center sends accurate and up-to-date link travel times to the RSU and then the vehicle for use in real-time dynamic routing. The travel times will be generated by the 511/TravInfo™ system.
3. Incident Information to Vehicles - The central processing center transmits real-time incident information to the RSU and then the vehicle, which can be programmed to present this information to the driver in accordance with installed equipment and selected options. The incident information will originate from the 511/TravInfo™ system.
4. Intersection Collision Warning – The local signal controller transmits signal timing (phase condition) information to the RSU and then the vehicle.
5. In-Vehicle Signage – Integration of roadside signage information into in-vehicle navigation system, e.g., speed limit, next exit information. Lays migration path to work zone warning.
6. OEM Specific Application – Encrypted message set specific to Original Equipment Manufacturer (OEM) requirements, passed between vehicle, RSU and OEM center.