SOUTHAMPTON SITE

Available Equipment

1. Route Guidance VMS

Between 1992 and 1995, as part of the ROMANSE project, a pilot trial of three route guidance signs, together with associated control equipment, were installed in Southampton. These signs were augmented by five mobile (trailer mounted) signs capable of being deployed during major incidents and special events. In early autumn 1998, a further 17 route guidance signs were installed (complemented by a further six signs on the western fringe of the city installed under the ENTRANCE project) on the city's arterial routes.

To support this expansion, a completely new control system was installed. This is linked via an ethernet to the Integrated Traffic Management Computer (ITMC), which is a development of the original UTC system allowing system operators to develop VMS strategies integrated with other systems within the TTIC.

Project staff have also worked closely with the Highways Agency on the development of a system of 17 Enhanced Message Signs (EMS) on the M27 Motorway around Southampton. This system became operational in August 1998 and is under the dual control of Hampshire Police and ROMANSE operators. The ROMANSE VMS control computer has an interface to the Motorway system which facilitates the development of an inter-urban VMS control facility and enables the implementation of integrated strategies to manage and control incidents and congestion. The locations of the VMS are illustrated in Figure 3.

2. Network Monitoring

There are over 100 sets of traffic signals in Southampton, the majority of which are controlled by the UTC system which incorporates SCOOT. In addition to co-ordinating the traffic signals, SCOOT provides a large quantity of real-time information including flow, delay, percentage occupancy and queue length. A database, ASTRID, has been developed to process and store this vast amount of information, and allows historic profiles of individual links to be graphically displayed.

Information is also collected from other sources such as the 90 UTC count detectors and SCOOT-type loop detectors which have been installed on four arterial routes in Southampton. Parallel research has been involved with the development of algorithms for the prediction of journey times on these routes, based on the occupancy records. However, there are still areas of the network where monitoring is particularly poor, and this is being addressed. Additional SCOOT detectors have been installed at key decision points to monitor behavioural response to the VMS. These detectors are not linked to traffic signals and, as well as providing useful data for evaluation, can potentially aid the operator in assessing the on-line impact of the VMS.

30 closed Circuit Television (CCTV) cameras have been installed at key locations around the city, including the motorway network, to monitor traffic conditions. The system has been enhanced by the ARTEMIS incident detection software system, which continually scans CCTV images and uses image processing techniques to detect unexpectedly slow moving or stationary traffic. The system can also gather statistical information on traffic speed, flow and lane occupancy.

3. Incident Management and Integrated Strategies

Incident Management in ROMANSE consists of three main components:

• Incident Detection;

• Incident Integration; and

• Strategy Management.

In ROMANSE, an 'incident' is defined as an 'unusual traffic flow in the network as indicated by 2 or more detectors'. Most incidents are localised in nature, and, typically, 100 to 150 'local' incidents a month occur. However, there are on average 1 or 2 incidents per month that affect significant portions of the network in Southampton.

A CONTRAM traffic assignment model of the Southampton road network has also been developed. This is used as a basis for the off-line RGCONTRAM model which has been used to investigate VMS strategies for potential incident scenarios. The result has been the creation of a large number of strategies for which the effectiveness has some sound theoretical background. A traffic management strategy is a collection of actions which, when implemented, assists with the management of traffic during an incident. A strategy may contain any number of different actions, some automatic and some manual. These actions can include commands to change traffic management and control strategies and provide traffic and travel information.

For example, the strategies for use in incident situations are based on 63 hypothetical incident locations on major roads or links in and around Southampton. For each incident location, the VMS that are relevant to drivers approaching that location from each direction have been identified from traffic modelling work. The severity of the incident is also important; messages warning of severe incidents are generally set on a wider range of VMS than less severe incidents. The strategies include approximately 100 pre-programmed messages for a number of hypothetical scenarios, including accidents, broken-down vehicles, and road works. Each specific combination of incident location, type and severity results in a specific set of VMS used and associated messages. Each unique combination is termed a strategy.

Incident Detection

Road traffic incidents in the urban network can be detected automatically using the INGRID algorithm. This operates within the Integrated Traffic Management Computer (ITMC) systems and examines the behaviour of traffic on adjacent SCOOT detectors throughout the signalised area. Its algorithms work in real-time and identify events which are abnormal both in absolute terms and also with reference to long term profiles of expected conditions. Incidents identified by the police are received automatically through the Travel Terminal network and are subsequently passed to the ITMC. In addition, the TTIC is manned throughout the day by operators who can identify incidents from CCTV, from the public by telephone, and from television or teletext. These are input directly to the ITMC.

Incident Integration

This function is performed by the Incident Management module of the ITMC. All incident reports, whether received automatically or manually, are geographically referenced. The common base for this is the UK national grid reference. Reports, which share the same or similar reference, are then combined together as the same incident. Each report has an importance factor associated with it. Hence the relative severity of incidents can be readily seen. Operators can access textual incident information in summary or detail form at any TTIC workstation. From the same workstation it is also possible to view the location of incidents against a map background, both at region and street level.

Strategy Management

The ITMC component of the TTIC has a Strategy Management module. Strategies are configured by manual entry into a database pro-forma. Strategies have a numeric identifier and a description. For each strategy, a number of commands can be input. Each command is an instruction for an action to occur when the strategy is run. Commands can be defined to occur immediately, at an offset time or at an absolute time. Commands can be defined to be actioned on systems such as VMS, UTC and Bus Stop signs. Once a command leads to action, it is stored automatically, and can be subsequently accessed to feed into a post-mortem analysis of the scenario.