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Glossary of Terms

IBTTA’s transportation Glossary of Terms is an ever-changing list of terms used within the transportation and tolling industry. The Glossary was updated in August, 2018.  If you have suggestions for future additions, please contact us.


  Glossary of Terms

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | R | S | T | U | V | W
Titlesort ascending Description
System Integrator

A contractor hired by an agency to build an electronic toll collection system with various parts supplied by different vendors. Essentially the “prime” contractor.


Sport Utility Vehicle


Electronic toll collection system used in Florida.


See also Eurovignette. A sticker or vignette proving that a distance or time-related toll has been paid by a user.


Toll rate is the same fixed price during any day or time of day (24/7). (May vary by vehicle/weight class or distance traveled).


Strategic Rail Authority in the United Kingdom.

Spread Spectrum Ethernet Radio

Communication systems where users transmit in the same bandwidth simultaneously. In this transmission technique, the frequency spectrum of a data-signal is spread using a code un-correlated with that signal.

Software algorithm

An established, recursive computational procedure for solving a problem in a finite number of steps.

Smart Card

A small plastic card embedded with a memory chip and often a microprocessor, used for financial transactions, identification, as a key, etc.

Single-Protocol Technology

An electronic toll system designed to recognize and operate with transponder devices using a single specific data transfer protocol.


The Signature is a code, encrypted by a Private Key, which may be used by third parties verify that data or transactions containing the Signature originated from a specific Private Key. For example, when the On-Board Unit Private Key is used to “sign” data, the Signature may be later verified by the Issuer as coming from the Private Key. This prevents an intermediary who does not know the Private Key from altering the message or its contents. As used here, a Signature is inserted in each transaction generated by an On-Board Unit. The Signature remains with that transaction until the transaction is processed by the Issuer. Issuer processes the transaction. This allows the Issuer to independently verify the source and integrity of the transaction.

Shadow Tolls

Per vehicle amounts paid to a facility operator by a third party such as a sponsoring governmental entity and not by facility users.


Système de Gestion des Cartes de l'Assurance Maladie

Service Provider

Any organization that provides a service, which is authorized and/or paid for through the use of a transponder. The most common example today is Toll Authorities. Other examples may be retailers, parking facilities, etc. who accept transponder transactions as payment or as part of ITS functions.


Schéma Directeur d’Information Routière. The road information master plan for France.


Schéma Directeur d’Exploitation de la Route. The national traffic management master plan for France.


Split Cycle and Offset Optimisation Technique. A traffic signal control system.


Sydney Co-ordinated Adaptive Traffic System. A traffic signal control system in Syndney, Australia.

Saturation limit

The point in a traffic condition where the arrival flow rate exceeds the maximum sustainable flow.


Safe Accountable Flexible Efficient Transportation Equity Act: A Legacy for Users - The Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU) is US federal transportation legislation, enacted Aug. 2005, which provided for funding and directions to suport the Federal-aid highway program.