The main objectives of road network monitoring can be summarised as follows:
Each objective is realised through various solutions, including the application of ITS technolgies.
Network monitoring is expensive. When considering the provision of monitoring systems it is important to establish the key purpose of collecting specific information and to design systems accordingly. Depending on the local context, information may be needed on a variety of factors – such as traffic and weather conditions, incidents and other road and highway status alerts – in order to provide intelligence for network operations activities, traffic control and information systems. Other examples are:
Managing events on the road network in real-time requires the means to detect and rapidly assess any situation that is potentially problematic as soon as it arises, with reliable procedures for a quick and suitable response.
To carry out these tasks, the desk operators must:
Analysis of the situation must have regard to:
This task demands major efforts to develop systems that capitalise on and disseminate past experience. Crucially it requires good staff coordination to avoid instances where staff work at cross-purposes during an emergency.
All the organisations and agencies that have a part to play in the network operation will have an interest in network monitoring activities. In planning, designing and allocating resources to the network monitoring system the equipment, information systems and operational procedures need to be specified in line with the coordination arrangements. In particular, when multiple partners are involved at the operations centre a flow of command needs to be established in order to ensure smooth implementation. (See Operating Agreements)
Agreement on operational procedures is especially important when the data being monitored are used for enforcement purposes. Usually, network operators do not have the power to actually catch or rectify the offending situation even when it is necessary to do so in order to ensure a smooth operation. Close planning and cooperation with enforcement agencies are critical. (See Enforcement)
The core data used to assess and manage the roadway is collected and collated by manual methods and automatically for use in both real time and non-real time applications. Choice of equipment and methods is dictated by the required services as well as the available human and financial resources. (See Methods & Procedures and Vehicles & Roadways)
Example data includes:
Care must be taken not to overload operators and systems with data and information without sufficient filtering or analysis. The following questions must always be addressed:
Certain constraints must be considered. The organisation will need to
ITS-related monitoring systems are characterised by the use of electronic sensors, data processing by a central computer, and data transmission. The system requirements are heavily dependent on the operational activities that it will support (operating, controlling and providing services) and the road network characteristics under consideration. (See Information & Data Gathering)
When an existing (legacy) system needs to be incorporated in the new monitoring system, it is important to evaluate the system applicability for continued use and whether it can satisfactorily accommodate new requirements.
Privacy is a critical issue when incorporating detection technologies that can identify individual vehicles. Typical technologies for these include CCTV, video image processing, automatic vehicle identification (AVI) and cell-phone tracking. It is therefore important to agree a policy of how to respect privacy at all stages: when information is collected, when it is being used and when it is exchanged and transmitted between relevant organisations, including making it available to the public. (See Privacy)
Automated incident detection is most commonly found in urban areas where traffic congestion during peak hour periods is experienced. However, initiatives such as e-Call (Europe) are developing integrated emergency response infrastructure, which will improve detection and response to incidents in all areas (rural and urban) by means of global positioning, in-vehicle sensors and satellite and cell phone technology. In-vehicle systems where on-board electronics improve the driver’s competence in congested travel conditions, at night or in bad weather, can also reduce the occurrence of incidents. (See Automatic Incident Detection)
In the case of automatic detection, the reliability of the monitoring system needs to be evaluated after installation, with respect to the detection function, the telecommunications function, the data processing function and the overall system function. Typical evaluation points include accuracy of measurement, timeliness of data transmission and processing, ability to provide required data, reliability of software algorithms, system resilience under required environmental conditions and maintenance costs.
In the case of non-automatic detection such as phone calls from users, the reliability and accuracy of the data also becomes an important issue. Another issue is the problem of operators receiving too many calls with redundant information. This often happens in the case of large accidents that many people can clearly observe.
Information from road users can be gathered directly by the traffic or operations centre or through a dedicated call centre. In both cases it is very important to handle the gathered information quickly and to confirm its value through the use of the other information sources (such as loops, cameras, mobile patrols). Information from drivers can also be a complementary input for the traffic centre database and is an important tool where monitoring equipment is limited.
User feedback concerning the efficiency of the roadway and traffic conditions is a useful input for determining the perception of the network monitoring operation. This can be achieved through:
Detection systems can enable information to be given to the network operator regarding the onset (or probability of onset) of difficult weather conditions (fog, black ice, snowfall, cyclones, dust-storms) or other unfavourable natural events (landslides, floods). The network operator's task is to respond by issuing appropriate advice on road use through all available channels. (See Traveller Services)
This requires systems for the collection, processing and centralisation of counts and information, organised relations with the safety and emergency call-out services or the assistance services, automatic or non-automatic warning systems (emergency call network, automatic incident detection), and the organisation of regular patrols on the most sensitive roads. (See Data Aggregation and Analysis)
Real-time data accumulation to serve as historical data is an important task of the monitoring mission. It can be used in such a way as to compare real-time data with historical data and find out the presence of incidents on the network. Before/after study of operations and control functions also depends on comparison of these data. In addition, historical data can provide important information to the ITS-unrelated programs of network improvement such as geometric improvement and pavement rehabilitation. (See Data Management and Archiving and Data Ownership and Sharing)
Information is provided here on a number of methods that are widely used in network monitoring at all levels of operation.
The responsibilities of patrol officers are to:
To carry out this task the patrol officer monitors the assigned network segment, reports and responds to minor incidents where appropriate. Patrols are developed only if an Operations Centre is capable of undertaking actions proposed by the patrol reports.
Patrol operating procedures, schedules and routes will depend on the department’s objectives and operating strategy, and they must be adjusted to meet actual needs (scope and frequency of problems) and resources available.
Patrols may be conducted in various patterns:
Patrol officers must carry, in their vehicle, a procedures manual, automatic response sheets, a logbook, a communications device (radio, telephone), and possibly response equipment.
Patrol officer training must include an introduction to specific reporting procedures and the submission of reports in a standardised format (For example: I am arriving on the site / I am leaving the site, traffic is reduced to one vehicle approximately every five seconds, the traffic jam is at least 600 m long and growing). (See Mobile Service Patrols)
Aerial observation missions provide the opportunity to complement raw data with an analysis and potential solutions together with real-time observations of driver behaviour and the effectiveness of response actions. Nevertheless aerial observations are expensive and are viable only for exceptional events and heavily trafficked areas that routinely experience a high frequency of disruptive incidents.
The duty desk essentially involves:
The specific resources for the duty desk include:
This task requires an intense effort in terms of organisation and communication both internally and externally but it also contributes to improving the department’s efficiency as much from the perspective of users as of partners.
Calls may be recorded in a format that includes:
The decisions made and actions taken must also be noted, including the date and time.
A log must be kept in real time and the information logged must be complete. The usefulness of a log is directly dependent on the experience and qualifications of the officer who writes it. In major events, a person must be assigned exclusively to this task.
Each participant in the operation of the road system must keep a log of their assigned tasks: after-hours duty officers, patrol officers, winter maintenance services, operating control centres, etc. The log may be kept in a notebook or electronically on a computer.
Since records may be used in legal proceedings, the log must be impossible to falsify (non-removable numbered pages or secure electronic copy).
Maintaining comprehensive logs (record everything in real time, as events unfold, with no possibility of changing entries after they are made) ensures:
To do this, the network operations department needs the ability to provide well-informed solutions based on expert analysis of traffic volumes, traffic distribution and the evolution of traffic trends. It must collate and validate data for future operational planning and for the provision of valuable traffic statistics.
The data required for traffic studies differs according to the problem to be addressed, for example:
Interpretation of counts often requires consideration of other factors such as weather data, incidents, accidents, major events. It is therefore necessary to relate the collated traffic data to records and observations summarising the day’s events.
Conducting traffic count studies requires high-performance counting equipment, and computers to process the date including:
The complexity of data management, count evaluation and simulation tools, requires basic training in traffic engineering and in statistics to ensure credible, relevant results.
The programme proceeds as follows:
The programme requires:
There is always the risk of an unexpected event (such as adverse weather, major disruptions on a neighbouring arterial) occurring at the last minute, making established forecasts totally irrelevant. Furthermore, some preventive operating measures may prove inadequate. However, regular attention to near-term and future traffic forecasts will reduce the likelihood and frequency of an emergency response being needed.