TRAFFIC CONTROL MEASURES
Traffic control covers all measures designed to distribute and control traffic flows over time and space in order to avoid the occurrence of incidents or reduce their impacts. Traffic control is carried out by network operators and controllers with reference to predetermined traffic management policies and plans. In most countries it is an activity carried out in coordination with the authorities responsible for traffic police, often under their direct control.
It is possible to distinguish between:
Direct control measures - using traffic lights, "smart" barriers and Variable Message Signals (VMS) to assign traffic priorities in time and space Compliance measures against violations of control measures and traffic laws - for example, surveillance cameras for speed and red light detection of operation linked to ANPR cameras
Indirect control measures, mainly information and recommendations to drivers that will affect the behaviour of individual vehicles, eg radio broadcasts, pre-travel information (via the Internet and mobile devices), vehicle routing and navigation systems to board. Systems)
INDIRECT CONTROL MEASURES
Indirect control measures can be characterised as preventive actions or corrective or corrective actions. Indirect control methods are supported by travel information systems.
The preventive action aims to warn drivers of current and forecast problems so they can make adjustments to their travel plans. It includes drivers warning of predicted problems , they can change their travel times, choose different routes or abandon their journey. This requires:
An ability to predict the impact of traffic disruptions (whether random, predictable, or recurring)
An evaluation of alternative routes, which can be used in case of difficulties
Dissemination of preventive information to users
Data generated by ITS field devices and floating vehicles (probes) are valuable resources that provide a basis for the use of simulation models that can predict congestion and / or travel times. This allows logistic system managers and CBT operators to take steps to prevent the onset of congestion-either by diversion or with advice on travel changes.
REMEDY OR CORRECTIVE ACTION
Corrective measures are designed to limit the extent or impact of delays and congestion occurring regularly on strategic routes, using measures to limit access and, at the regional level, to divert traffic to less congested routes. The diversion routes should be planned in cooperation with the road authorities and the operators of the alternative routes. Often, a high capacity alternative route will not be available and other options would only be suitable for light traffic, not for trucks and heavy vehicles. Some road authorities operate seasonal "holiday routes". Others will only divert traffic when there is a road closure or an emergency (except in ramp meters, where the deviation is indirect).
Corrective action requires:
1. Contingency plans for traffic management to be developed jointly with stakeholders (such as emergency services or other road operators) that will be affected by the measures, if applicable
2. A system for the detection and permanent or temporary monitoring of traffic conditions in the road network: collection, centralization and processing of data in order to diagnose the situation, how it can be developed and initiate measures of traffic management
3. Installation of CCTV in "hot spots" congestion to support the monitoring of network conditions
4. Installation of specific equipment to communicate network control information to drivers at strategic points in the network, such as Highway Advisory Radio or text VMS
5. Real-time road user information systems to generate messages on traffic disturbances, with alternative routes or directions
6. The use of lane-specific speed limit pictograms on variable message signs for routes with heavy traffic as part of an active traffic management scheme
7.The use of mobile security service patrols to close access and implement diversion signals in the absence of automatic systems or when field monitoring is required.