Traffic and Road Network Management

Traffic control aims to manage and control the movement of traffic on roads to optimise the use of existing road capacity. ITS applications include:

• urban traffic control that is demand-responsive and may incorporate transport policy elements – such as public transport prioritisation or queue management
• adaptive signal control systems along arterial roads that adjust signal timings to current traffic conditions – such as those caused by special events or incidents
• freeway control systems that use ramp metering and lane control techniques to smooth traffic flow
• integration of highways and network signal systems for the purpose of corridor or “area-wide” optimisation of traffic flow

The implementation of effective traffic control strategies requires timely and accurate traffic information. The better the data, the more effective the control strategies that can be implemented. Information is gathered from various sources – such as detector loops in the road pavement, roadside and overhead sensors and analysis of digital camera images. The data can be combined and used to decide upon the best (or optimal) course of action for managing traffic on the network. (See Traffic Control)

Traffic control is one of the most basic building blocks of an intelligent road transport system, since it requires detection, control, communications and support systems – that are fundamental to the operation of several other ITS services. Traffic control and traffic operations centres (TCCs and TOCs), responsible for these functions, now exist all over the world. (See Traffic Control Centres)

ITS plays a significant role in improving incident management, particularly on highways, motorways and other high speed roads. This is because it uses vehicle sensors (such as inductive, buried, loops, radar and CCTV cameras), data processing and communications technologies to quickly detect and verify an incident. Sophisticated decision support systems then help traffic managers to decide how to best respond to any given incident. Using ITS in this way can improve safety and network efficiency, saving lives and money. (See Traffic Incidents)

One of the application areas where ITS has achieved great success is in the area of electronic payment. Among the prime examples of electronic payment are Electronic Toll Collection (ETC) systems such as the EZPass System in the USA or the European Electronic Toll Service. These systems allow drivers to pay road tolls without stopping or slowing down their travel speed – minimising delays and improving air quality in the vicinity of toll plazas.

ETC systems can take various forms such as:

• a mainline toll plaza with payment at the barrier;
• an open highway collection system where tolls are collected at main-line speeds;
• a closed system where tolls are charged based on entry and exit locations.

These systems can impose different tolls for different classes of vehicles, and can provide for the automatic enforcement of violations. Other examples include integrated payment systems – designed to allow a traveller to pay for different services (for example driving on a toll road, paying for parking, paying for transit) using the same medium or device (See Electronic Payment).

ITS can be applied to implement strategies aimed at increasing the frequency of Multiple-Occupancy Vehicles (MOVs) and promoting the use of High-Occupancy Vehicle lanes (HOVs). ITS can help make the operation of HOV lanes more effective and adaptive to changing traffic conditions – by adjusting vehicle occupancy requirements at different times of day, based upon current traffic and congestion levels. ITS also can help implement congestion pricing strategies – where toll charges are adjusted to influence demand. For example, tolls can be increased during peak hours in urban areas or in the vicinity of environmentally sensitive tourist attractions in rural areas. (See Demand Management)

ITS can be applied to better manage the allocation and price of parking spaces. This helps improve the travel experience of drivers by providing real-time information on spaces in parking lots. ITS-based parking information systems can be integrated with city-wide traffic management and control – to minimise parking search times and optimise traffic management overall. Electronic toll tags can also be used as a means of controlling access to a controlled parking area. (See Access Control)

ITS can help improve the environmental sustainability of road transport. Some ITS applications use environmental sensors to collect information about exhaust emissions from vehicles at a certain location, or over a wide area. The information can then be used to intelligently divert traffic away from areas where air quality has fallen below an acceptable threshold – or by not letting vehicles access these environmentally sensitive areas. The information can also provide valuable input to the development of air quality improvement strategies – and to alert vehicles’ operators if their vehicles are not compliant with adopted emissions standards. ITS can also be used to manage congestion and reduce delay – which has beneficial impacts on emissions and air quality. (See Driver Support)

The purpose of a highway-rail intersection ITS application, is to provide improved warning and safety control devices where a railway (railroad) crosses a road or highway at a level crossing (an “at-grade” crossing). On the approach roads to the crossing, any signalised intersections can be connected to the control and warning devices at the highway-rail intersection (HRI), so that signals can be coordinated to manage queuing and divert traffic. The technology can also monitor the “health” of HRI equipment – and report any detected malfunctioning. (See Enforcement)

ITS system and service applications have an important role to play in emergency situations:

• emergency notification and personal security applications;
• emergency vehicle management;

Emergency notification and personal security applications include systems that:

• allow a driver to initiate a distress call in the event of an incident (emergency and a non-emergency such as mechanical breakdown);
• enable the vehicle itself to automatically notify emergency management services (EMS) personnel in the case of a collision.

The European eCall and American OnStar systems are good examples:

• eCall: http://ec.europa.eu/digital-agenda/en/news/ecall-all-new-cars-april-2018;
• OnStar: https://www.onstar.com/web/portal/home?g=1).

Emergency vehicle management focuses on applications intended to reduce the time from the receipt of an emergency notification to the arrival of the emergency vehicle at the scene of the incident. This is accomplished through:

• optimal emergency fleet management – to identify the locations of emergency vehicles in real-time and dispatch the vehicles that can reach the scene of the incident most quickly;
• dynamic route guidance – to guide the emergency vehicle to the fastest route to the incident scene or a suitable hospital;
• signal priority or pre-emption – to give priority to trams and buses. (See Emergency Response)