A typical installation will consist of one or more roadside sites (“outstations”), at which the traffic observations are collected, and an office-based machine (“instation”), often at the client’s own premises, where the observations collected from the outstations are analysed and made available to the system’s users. NCTR has developed a system architecture which is designed to use existing communications infrastructure as much as possible. In particular, we believe the Internet provides the basis for cheap, flexible, and very scalable data transport between outstations and instation. Our communications use standard, widely-used protocols throughout, and the architecture is designed to use clients’ existing private networks and Internet connections whereever possible, which helps to keep installation and running costs low.
Our instation software collects the data generated at the outstations, and presents the output on a graphical user interface which is accessible through a Web server. The advantage of this type of data presentation is that it requires users to have nothing more than a standard Web browser, which is found on almost all office computers.
The standard instation has the following functionality:
The raw data collected from the outstations (individual ANPR or loop observations) and derived quantities (such as individual vehicle journey times) are available through an HTTP interface to the instation database for further analysis by the user. Making the data available through a defined interface using a standard protocol (HTTP) assists integration into a larger traffic information system.
In addition, we offer a number of optional features:
Programmable outstation calling intervals are especially useful where communication costs are important. The outstations can send in data frequently during periods of particular interest (morning and evening rush hours, for example), and less often at other times (such as during the night or at weekends).
We are also pleased to discuss the use of our instation software in conjunction with outstation software from other suppliers.
Apart from ANPR analysis of incoming video from the cameras, the outstation software can also collect data from other devices such as induction loops. It also performs other ancillary tasks such as the measurement and reporting of outstation temperature to avoid overheating, and synchronisation of the system clock with external standards (usually Internet NTP servers) for accurate timing of observations.
Our outstation software typically runs under the Debian GNU/Linux operating system, which provides a flexible, general-purpose platform in a multi-tasking Unix-like environment. This allows project-specific customisation (such as extra diagnostics, or data acquisition from other devices), to be done quickly and cheaply. No licence fees are payable for the Linux operating system, thereby reducing system costs.
Our software does not require any custom-built or special-purpose hardware, and both outstations and instation are usually run on standard Intel-compatible hardware, which provides high performance at low price. We have used ADSL, ISDN, PSTN and GSM communications at outstations, and are happy to discuss other methods.
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