Clovis Variable Speed Limit Sign - 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: 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 Probe Data Communications
Field elements that collect probe data from vehicles using short range communications.
| ID | Requirement | Status |
|---|---|---|
| 2 | The field element shall communicate with on-board equipment on passing vehicles to collect current vehicle position, speed, and heading and a record of previous events (e.g., starts and stops, link travel times) that can be used to determine current traffic conditions. | Planned |
Functional Area: Roadway Traffic Information Dissemination
Driver information systems, such as dynamic message signs and Highway Advisory Radio (HAR).
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall include dynamic messages signs for dissemination of traffic and other information to drivers, under center control; the DMS may be either those that display variable text messages, or those that have fixed format display(s) (e.g. vehicle restrictions, or lane open/close). | Existing |
| 4 | The field element shall provide operational status for the driver information systems equipment (DMS, HAR, etc.) to the center. | Existing |
| 5 | The field element shall provide fault data for the driver information systems equipment (DMS, HAR, etc.) to the center for repair. | Existing |
Functional Area: Roadway Variable Speed Limits
Field elements including physical overhead lane signs and associated monitoring, communications, and control electronics that are used to manage and control variable speed limits systems.
| ID | Requirement | Status |
|---|---|---|
| 1 | The field element shall monitor traffic and environmental conditions along the roadway. | Existing |
| 2 | The field element shall autonomously calculate and set variable speed limits based on current conditions by lane. | Existing |
| 3 | The field element shall receive commands from the controlling center that establish speed limits by lane. | Existing |
| 4 | The field element shall display the current speed limits per lane to drivers. | Existing |
| 5 | The field element shall display additional information such as basic safety rules and current traffic information to drivers. | Existing |
| 6 | The field element shall collect operational status of the variable speed limit field equipment and report the operational status to the controlling center. | Existing |
| 7 | The field element shall monitor and report faults to the controlling center. | Existing |