Municipal ITS Field Equipment - 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: Multimodal Crossing Control
Field elements to monitor and control traffic at multimodal crossings, such as draw bridges and other crossings between highway traffic and other modes; does not include highway-rail intersection.
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 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.
Functional Area: Roadway Field Device Monitoring
Monitors field equipment operational status and detects and reports fault conditions. Device status, configuration, and fault information are provided to a remote center and a user interface provides information locally to field personnel.
Functional Area: Roadway Mixed Use Sensing
Provides the field devices that provide sensing and warning systems for pedestrians, bicyclists, and other vehicles that operate on the main vehicle roadways, or on pathways which intersect the main vehicle roadways.
Functional Area: Roadway Safety Warning System
Monitors for potential safety hazards including wrong way drivers, debris on the road, and adverse road conditions (e.g., standing water, icy conditions) and warns approaching vehicles of potential hazards.
Functional Area: Roadway Signal Controls
Field elements including traffic signal controllers for use at signalized intersections; also supports pedestrian crossings.
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
Functional Area: Roadway Signal Priority
Field elements that provide the capability to receive transit vehicle signal priority requests and control traffic signals accordingly.
Functional Area: Roadway Speed Monitoring and Warning
Vehicle speed sensors that detect excessive vehicle speeds, optionally based on conditions and vehicle type, informing drivers, centers and/or enforcement agencies of speed violations.
Functional Area: Roadway Traffic Information Dissemination
Driver information systems, such as dynamic message signs and Highway Advisory Radio (HAR).
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.
Functional Area: Roadway Work Zone Traffic Control
Field elements in maintenance and construction areas including CCTV cameras, driver information systems (such as DMS), and gates/barriers that monitor and control traffic and provide information directly to drivers in affected areas.
Functional Area: Standard Rail Crossing
Field elements at highway-rail intersections (HRIs) where operational requirements do not dictate advanced features (e.g., where rail operational speeds are less than 80 miles per hour). Includes traditional HRI warning systems augmented with other standard traffic management devices.