Results for area 5 Traffic Control Systems
roadside equipment that communicates with the roadside units such as signal controllers and the in-vehicle units using radio signals
top layer of the OSI seven-layer model as defined in ISO/IEC 7498-4
NOTE This layer defines the structure and format of the data packet content along with the rules and procedures for exchanging data packets.
computer or network that is required to meet a standardized communications interface over a fixed-point communications network, regardless of whether it is the only system within the building or just one of many, or even if it is located in the field
system or device to which the information in the data packet is intended to be sent
process or program using the communications stack
identifier of an application-entity to a transport service in the internet suite of protocols
NOTE The concept of port numbers is often present in OSI literature; however, port numbers are not inter-network standardized, but exist as local network conventions only.
entity of data containing enough information to be routed from source to destination without relying on previous network configuration
EXAMPLE IP datagram.
entity of data that can be sent between end-application systems in order to exchange information
NOTE A data packet relates to the Application Layer of the OSI stack and may be broken into several pieces by lower layer protocols.
detector that detects vehicle identities based on wireless communication with tags or on-board units (OBU) in the vehicle, which transmits the vehicle's identity information to the traffic signal controller
the central system that controls the functions of traffic data collection, signal control, and information service based on collected data, etc.
specific combination of physical and data link layer protocols as defined in IEEE 802.3 that allow multiple systems to gain access to a shared medium and communicate with one another
definition of the physical coverage of the service
DATEX-ASN mechanism in which the client acknowledges the receipt of a publication (reply)
definition of the geographic area covered by the service
data packet sent to indicate that the sending system is still alive and communicating
identification number used for the identification of emergency and/or public transport vehicles
the identity of the model when collection method is estimated via a mathematical model or simulation
information type that designates the type of information from linked detectors which can be occupancy based, image processing based or vehicle identification based
specific instance of an end application message
interval of data update
roadside equipment that communicates with the in-vehicle units and the roadside units, e.g. beacons and antennas
verification flag indicating whether the data value has been cross verified from one or more additional sources
maximum amount of time a system is given to provide an appropriate response to the incoming data packet
method used to obtain data, for example manual or computation
the method used for calulation or estimation
set of basic messages that are normally used in business-oriented applications
terminal units controlled or monitored by a traffic management centre
NOTE Roadside modules are usually installed at the roadside arena.
indicator whether the use of data is restricted or not
period over which the values are determined
logical channel in a communications system
NOTE UDP and TCP use port numbers to multiplex data packets from a variety of applications onto a single communications system.
rules which specify the representation during transfer of the values of ASN.1 types
NOTE 1 Encoding rules also enable the values to be recovered from the representation, given knowledge of the type.
NOTE 2 For the purpose of specifying encoding rules, the various referenced type (and value) notations, which can provide alternative notations for built-in types (and values), are not relevant.
reference model developed by ISO to enable different or similar systems to dialogue with one another
NOTE 1 This model constitutes a reference framework for describing data exchanges. Each layer performs a service at the request of the adjacent higher layer, and in turn, requests more basic services from the lower layers. It is described in 7 layers.
NOTE 2 Open systems interconnection (OSI) is an international effort to facilitate communications among computers of different manufacture and technology.
identification, version and date of the spatial data set used
set of services which are responsible for providing a virtually error-free, point-to-point connection so that host A can send data packets to host B and they will arrive uncorrupted
NOTE Connection-oriented transport profiles may also ensure that the data packets arrive in the correct order.
service that provides end-system to end-system communications without any connection set-up
EXAMPLE UDP/IP.
data packet which is prepared by one system in order to control some function(s) of another system
NOTE Commands may be conveyed as a subscription (request) or publication (reply) depending on the design of the specific data exchange.
service that allows one end-system to exchange a continuous stream of data with another end-system, the data of which is guaranteed to be delivered in the same order in which it was sent without any duplication
NOTE This service is typically achieved by first establishing a connection, then sending the data, and finally terminating the connection.
EXAMPLE TCP/IP.
reply data which have been prepared by a server, usually in response to a subscription
NOTE In some cases, a publication may be termed a “reply” or a “response”.
DATEX-ASN publication (reply) that is sent directly over the given transport profile, in contrast with a file publication
DATEX-ASN publication (reply) that is stored on the server’s file system until the client has an opportunity to retrieve it via a file transfer protocol, in contrast with datagram publication
period of time during which a client and a server exchange multiple data packets
layer that manages the dialogue between end-user application processes including restart, termination, and checkpointing
NOTE The session layer constitutes layer 5 of the OSI model.
direction of travel of a target within the detection zone
roadside equipment that controls the lighting timings of traffic lights
layer that provides functional and procedural means of transferring variable length data sequences from a source to a destination
NOTE The network layer constitutes layer 3 of the OSI model.
mean time to repair the service (MTTR) fault and bring the service back into operation
request data packet which is prepared by a client in order to request current or future publication(s)
NOTE In some cases, a subscription may be termed a “request”.
to ignore a data packet
NOTE A data packet that is silently dropped does not cause any action to occur within the receiving system, nor is any response sent to the subject data packet.
the conceptual layer of control or processing logic existing in the hierarchical structure of a station that is responsible for maintaining control of the data link
NOTE The data link layer functions provide an interface between the station higher layer logic and the data link. These functions include address/control field interpretation, channel access and command PDU (protocol data unit) /response PDU generation, transmission and interpretation.
identification of the type of equipment used to collect the raw data
identifies the type of locations
identification of the location referencing standard used including any version and date
the invehicle equipment that transmits/receives information to/from the Roadside Communication Units and, in some cases, outputs information on its screen, etc.
maximum duration a system is required to wait for a response data packet prior to assuming that the previously sent data packet was never received by the other application
roadside equipment that communicates with the roadside units such as the signal controllers and the in-vehicle units
standardized determination of data encoding to conform to the requirements of ISO 8824, ASN.1
NOTE The Basic Encoding Rules are given in ISO 8825.
system which created and sent the DATEX-ASN data packet
system or device which was the source for all of the information in the data packet
NOTE In many cases, this will be the same as the sender, but could be different. For example, a bridge (or proxy agent) may translate between protocols; in this case the bridge (or proxy agent) would be the sender, while the system generating the data would be the origin.
message data structure that has been associated with a specific meaning and which, when properly sent in a data packet, an instance of the structure can convey information between systems
NOTE A data structure might, for example, be specified to include a list of speeds from detector stations. This one data structure could be used to specify the content of several messages (e.g. the list of current speeds being detected, the list of stored speeds that will trigger a congestion warning if current values fall below the indicated level, or a request for a list of locations where the current speed is less than the indicated speed). An instance of the message would then contain actual values.