Caltrans D6 Vehicle Detection Systems - Roadway Functionality
Subsystem Description
The Roadway Subsystem (RS) includes the equipment distributed on and along the roadway that monitors and controls traffic and monitors and manages the roadway itself. Equipment includes traffic detectors, environmental sensors, traffic signals, highway advisory radios, dynamic message signs, CCTV cameras and video image processing systems, grade crossing warning systems, and freeway ramp metering systems. HOV lane management, reversible lane management functions, and barrier systems that control access to transportation infrastructure such as roadways, bridges and tunnels are also supported. This subsystem also provides the capability for environmental monitoring including sensors that measure road conditions, surface weather, and vehicle emissions. In adverse conditions, automated systems can be used to apply anti-icing materials, disperse fog, etc. Work zone systems including work zone surveillance, traffic control, driver warning, and work crew safety systems are also included. To enhance security, safeguard systems such as blast shields, exhaust systems and other automated and remotely controlled systems to protect transportation infrastructure is also provided. In advanced implementations, this subsystem supports automated vehicle safety systems by safely controlling access to and egress from an Automated Highway System through monitoring of, and communications with, AHS vehicles. Intersection collision avoidance functions are provided by determining the probability of a collision in the intersection and sending appropriate warnings and/or control actions to the approaching vehicles.
Functional Area: Field Barrier System Control
Field elements that control barrier systems such as gates and other systems that manage entry to roadways, transportation facilities and infrastructure.
Functional Area: Field Safeguard System Control
Field elements that control safeguard systems such as blast shields and tunnel exhaust systems that are used to mitigate the impact of incidents on transportation infrastructure.
Functional Area: Roadway Basic Surveillance
Field elements that monitor traffic conditions using loop detectors and CCTV cameras.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall collect, process, digitize, and send traffic sensor data (speed, volume, and occupancy) to the center for further analysis and storage, under center control. | Planned |
Functional Area: Roadway Data Collection
Field elements to collect traffic, road, and environmental conditions information for use in transportation planning, research, and other off-line applications. Includes the sensors, supporting roadside infrastructure, and communications equipment.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall collect traffic, road, and environmental conditions information. | Planned |
| 2 | The field element shall include the sensors and supporting roadside devices that sense, collect, and send traffic, road, and environmental conditions information to a center for archival. | Planned |
| 3 | The field element shall collect sensor status and sensor faults from roadside equipment and send it along with the recorded data to a center for archival. | Planned |
Functional Area: Roadway Environmental Monitoring
Environmental sensors, surface and sub-surface, that collect weather and road surface information. Weather conditions measured include temperature, wind, humidity, precipitation, and visibility. Sensors measure road surface temperature, moisture, icing, salinity, etc.
Functional Area: Roadway Equipment Coordination
Field elements that control and send data to other field elements (such as environmental sensors that send data to a DMS or coordination between traffic controllers on adjacent intersections), without center control.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall include sensors that provide data and status information to other field element devices, without center control. | Planned |
Functional Area: Roadway HOV Control
HOV lane usage traffic sensors and display equipment to notify users of HOV lane status for control of traffic in HOV lanes on freeways.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall include sensors to detect high-occupancy vehicle (HOV) lane usage, under center control. | Planned |
Functional Area: Roadway Incident Detection
Field elements that monitor traffic conditions to identify incidents. It includes traffic detectors that collect traffic flow information and identify unusual traffic conditions and advanced CCTV cameras with built-in incident detection algorithms.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall collect, process, and send traffic images to the center for further analysis and distribution. | Planned |
| 2 | The field element shall remotely process video data and provide an indication of potential incidents to the traffic management center. | Planned |
| 3 | The field element's video devices shall be remotely controlled by a traffic management center. | Planned |
| 4 | The field element shall provide operational status and fault data for the incident detection devices to the traffic management center. | Planned |
Functional Area: Roadway Probe Data Communications
Field elements that collect probe data from vehicles using short range communications.
Functional Area: Roadway Short Range Traveler Information Communications
Field elements that distribute information to in-vehicle equipment. The information provided may be determined locally or under the control of a center.
Functional Area: Roadway Warning
Field elements used to warn drivers approaching hazards including adverse road weather conditions, traffic conditions including queues, and obstacles or animals in the road.