City of Fresno Traffic Signals - 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 Management Stations Operation
Supports direct communications between field management stations and the local field equipment under their control.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field management station shall accept configuration information from the center. | Planned |
| 2 | The filed management station shall pass data provided by the center to local field devices and report data from the field devices back to the center. | Planned |
Functional Area: Roadway Basic Surveillance
Field elements that monitor traffic conditions using loop detectors and CCTV cameras.
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.
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.
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.
Functional Area: Roadway Probe Data Communications
Field elements that collect probe data from vehicles using short range communications.
Functional Area: Roadway Signal Controls
Field elements including traffic signal controllers for use at signalized intersections; also supports pedestrian crossings.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall control traffic signals under center control. | Existing |
| 2 | The field element shall respond to pedestrian crossing requests by accommodating the pedestrian crossing. | Existing |
| 3 | The field element shall provide the capability to notify the traffic management center of pedestrian calls and pedestrian accommodations. | Existing |
| 4 | The field element shall report the current signal control information to the center. | Existing |
| 5 | The field element shall report current preemption status to the center. | Existing |
| 6 | The field element shall return traffic signal controller operational status to the center. | Existing |
| 7 | The field element shall return traffic signal controller fault data to the center. | Existing |
| 8 | The field element shall report current transit priority status to the center. | Planned |
Functional Area: Roadway Signal Preemption
Field elements that receive signal preemption requests from approaching emergency vehicles and overrides the current operation of the traffic signals
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall respond to signal preemption requests from emergency vehicles. | Existing |
Functional Area: Roadway Signal Priority
Field elements that provide the capability to receive transit vehicle signal priority requests and control traffic signals accordingly.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall respond to signal priority requests from transit vehicles. | Planned |