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Office of the Assistant Secretary for Research and Technology
ITS Joint Program Office

Application Areas

Ramp Metering


This center-to-field application area covers the interface between a traffic management center and ramp metering equipment in the field. The ramp meter control (RMC) unit meters freeway entry lanes in order to restrict the flow of traffic onto the freeway. The RMC has a metering plan that is either locally stored or can be loaded from the traffic management center. The metering plan can be adjusted manually or automatically based upon traffic sensor data gathered from the mainline or metered lanes.
This graphic shows the scope of the Center to Field Ramp Metering application area.  This scope is described in the preceding text.
National ITS Architecture Interface
This application area includes the interface between the Traffic Management Subsystem (TMS) and the ramp metering equipment and traffic sensor equipment in the Roadway Subsystem (RS). The TMS remotely controls the ramp metering and traffic sensor equipment by sending initialization, control and operating parameters, as well as requests for equipment status and condition to the RS. The field equipment responds with the current operating status information (including fault information) and control settings, when requested.

Applicable Standards

In general, the following standards are applicable to Ramp Metering deployments. To determine which specific standards are applicable for a deployment you will need to determine which architecture flows will be needed for the Ramp Metering piece of your deployment. Contact your local FHWA ITS Division Specialist or an ITS Standards Program Field Support Team contact

Standard Development Status
ATC 5201 (ITE ATC Controller) Advanced Transportation Controller (ATC) ; Published
ATC 5301 Advanced Transportation Controller (ATC) Cabinet Version 02; Published
ITE ATC API Application Programming Interface (API) Standard for the Advanced Transportation Controller (ATC); Published
NTCIP 1102 Octet Encoding Rules (OER) Base Protocol; Published
NTCIP 1103 Transportation Management Protocols (TMP); Published
NTCIP 1201 Global Object Definitions; Published
NTCIP 1207 Object Definitions for Ramp Meter Control (RMC) Units; Published
NTCIP 1209 Data Element Definitions for Transportation Sensor Systems (TSS); Published
NTCIP 2101 Point to Multi-Point Protocol Using RS-232 Subnetwork Profile; Published
NTCIP 2102 Point to Multi-Point Protocol Using FSK Modem Subnetwork Profile; Published
NTCIP 2103 Point-to-Point Protocol Over RS-232 Subnetwork Profile; Published
NTCIP 2104 Ethernet Subnetwork Profile; Published
NTCIP 2201 Transportation Transport Profile; Published
NTCIP 2202 Internet (TCP/IP and UDP/IP) Transport Profile; Published
NTCIP 2301 Simple Transportation Management Framework (STMF) Application Profile; Published
NTCIP 2302 Trivial File Transfer Protocol (TFTP) Application Profile; Published
NTCIP 2303 File Transfer Protocol (FTP) Application Profile; Published
NTCIP 8003 Profile Framework; Published
NTCIP 9001 NTCIP Guide; Published
SAE J2266 Location Referencing Message Specification (LRMS); Published
Deployment Resources
Deployment resources can be found in the deployment resources section.