Uncertainty over journey and arrival times is a major problem for travellers and companies delivering goods. ‘Smart’ travellers and fleet managers increasingly expect reliable information to help them make well-informed decisions.
Accurate, integrated and comprehensive travel and traffic information helps all road users in their journey planning decisions and how to respond to disturbances that occur on the way. In this respect it supports the task of the road network operators as well.
Travel information – and by extension route advice – is considered to be a basic service. It constitutes the lowest level of traffic management. Road users are free to decide for themselves if and how to react to the information or advice.
Investment in travel information systems by the road operator is a way of improving customer service. Information systems can also promote intermodal travel, for example by encouraging drivers to leave their cars at a Park and Ride site (typically because of localised congestion or high pollution levels ahead) and continue by public transport. Parking information systems also contribute significantly to reducing city-centre congestion and pollution by alerting approaching drivers to available spaces.
Traffic information concerns the conditions of road network use and can include predictive and current (real-time) information on traffic conditions. Stronger forms of direction include hazard messages or incident warning, and eventually control measures such as notice of road obstructions, lane control, or speed control.
Traveller aid covers all measures to disseminate predictive or current information on traffic conditions and to improve general conditions of network use. Its general aim is safety and user comfort.
Travel aid tasks are not specifically aimed at modifying traffic flows. However, when used for information purposes they must be closely coordinated with traffic management measures as they may induce users to change their travel time, route or mode of transport. In this context, they may be integrated in broader strategies related to demand management.
Generation of travel information by the network operator is a broad concept that cuts across the entire field of operations and entails several areas:
To be able to inform partners and drivers effectively, operators must first define information paths that should be coherent with the operation and management plans.
To fulfil the needs and expectations of everyone involved, the information should be timely and disseminated via all available channels and communication modes. They can be channels operated directly by the control centres (variable message signs, travel information website, RDS-TMC, traffic news broadcast etc.) or by added-value service providers who transform the information into the required data formats for smart phones and satellite navigation, and/or operate additional dissemination channels themselves. (See Traveller Services)
Provision of client-specific, personalised (enriched) information is often let to independent, value-added service providers, who extend and build on the information stream made available by the road operator. However, there should be an agreed framework for safety-related advice and direction in the absence of specific instructions from the traffic centre, in order to avoid confusion or the undermining of the set traffic policy.
The purpose of this approach for the road operator is to achieve widespread, timely information dissemination to operating partners or road users, as required. This action involves listing all components of the information system, identifying blockage points and organising or reorganising the information chain to ensure the system functions effectively. (See Systems Approach)
Successful dissemination of information is the end result of a system in which each link is crucial to success, so the operator must ensure that each link functions effectively:
Computers can be used to automate all or part of the actions described above. (See ITS & Network Monitoring)
When information for users is relayed by an intermediary – especially the media – operators must listen to and/or read the messages actually sent by the intermediary, noting the date and time sent, to assess the quality of communication.
An information system is more effective when all players involved have a good overview and a clear understanding of their role. The quality of information received by users is very closely linked to the actual systems and can actually enhance the department’s image.
The common objective of all traveller information services is to provide high quality, real-time, detailed information on transport operating conditions, including weather, so that individual travellers can make informed decisions regarding whether to make a trip, when to make it, what mode to take, and what route to take. Traveller information should be available both before a traveller begins a trip, as well as while the trips are under way, so that adjustments can be made to reflect changing operational conditions.
Traveller information can be provided in a number of ways. A summary is provided here. (See also Traveller Services and Driver Support)
In recent years the Internet has become ubiquitous as method of conveying pre-trip traveller information. Some systems offer subscribers the option of receiving alerts by mobile phone, e-mail, or other electronic methods regarding major incidents or conditions on specific routes. Telephone dial-up services remain a popular means of pre-trip and en-route information dissemination. Commercial broadcast media, including radio, cable television, commercial television, and teletext services are other commonly used methods of dissemination of travel information.
Telephone: In the United States, a nationwide three digit telephone number, 511, has been designated for traveller information services. The success of this initiative lies in issues such as the perceived accuracy, timeliness and permanent operation of the 511 service. Also, because of the variety of organisations involved (geographically, public/private, different travel modes), the issue of co-operation is the other challenge. The success of this initiative shows that appropriate institutional agreements, when designed early enough in the development process, can be a powerful lever to deploy effective ITS operations services. (See Journey Planning)
Driver information systems: by means of roadside VMS or in-vehicle units, contribute generally to a better performance of the traffic system by raising the level of awareness of drivers about the current status of the network and its likely evolution. Users of traveller information services generally agree that availability of high quality, real-time traveller information saves time, helps them to avoid congested locations and incidents, and reduces uncertainty and stress associated with travel. (See En-Route Information)
Variable Message Signs (VMS) are used to disseminate en-route traveller information in virtually all locations where electronic traffic monitoring also exists. These signs are typically placed in advance of key bottlenecks or decision points and can display fairly detailed information on location and extent of congestion, travel times, alternate routes, and downstream weather conditions (for example wind, precipitation, snow). (See Use of VMS) Highway Advisory Radio is also used, although its use appears to be declining with the growing popularity of traffic-responsive satellite navigation units and smart phone applications, which are now widespread. (See Radio)
In-vehicle navigation: En route information provided through in-vehicle navigation systems and smart phones is spreading. The VICS system in Japan, which enjoys a high market penetration of in-vehicle navigation systems, is one of the most extensive applications. Dissemination of detailed en-route information is accomplished through transmission from beacons or FM sub carrier broadcasts to the in-vehicle device. Other countries have followed Japan in deploying this kind of system. (See Advisory Systems)
Subscription services: Pre-trip and en-route information alerts provided through social media, messaging subscription services (Internet and Smartphone) is growing in popularity.
Information terminals and kiosks: Pre-trip traveller information in kiosks located in employment centres and other public places (e.g. freeway rest areas and shopping malls) are becoming commonplace, although the experience with kiosks this dissemination method has limited utility for real-time road information. Use of kiosks for public transportation information appears to be more successful. Real-time public transportation information is also successfully disseminated at transit stops in many locations using electronic signs. (see Kiosks)
Information requirements are set by network operations stakeholders, transport operators, emergency services or assistance providers and road users themselves – the latter possibly clustered in Motoring Clubs and Road User Organisations. As might be expected, there can be some variety in the geographical extent and the level of detail of the information these players need in support of their activities, or to really fulfil their travel needs.
Predictive information: This information may be on a weekly, daily or even hourly basis and concerns general traffic condition forecasts and the main anticipated disturbances. Its implementation requires:
Real-time information: This information concerns the currently-experienced traffic conditions and disturbances affecting motorists on a given route. It requires:
Real-time information also includes information to operators of customised services or navigation and guidance systems.
High quality traveller information services must be driven by high quality data on transportation system conditions and performance. Effectively fusing data into useful information from various input sources is a significant challenge that is critical to overcome if traveller information services are to be effective.
For systems that automatically post or otherwise provide traveller information based on input from traffic monitoring systems, data reliability is a critical issue. Effective automatic means of checking or filtering raw data must be in place to ensure that erroneous or misleading information is not posted.
In order to be useful to travellers, traveller information needs to be multi-modal (road and transit), and regional (crossing jurisdictional boundaries) in scope and include information about motorways and urban streets, as well as location and availability of parking.
Travellers are interested in receiving end-to-end trip information in a single query. The objective for end-to-end travel planning involves links to intercity travel providers, such as rail and air lines, to provide complete travel and routing information, door-to-door. Future enhancements for end-to-end travel may include linking to intercity travel providers, such as rail and air lines, to provide complete travel and routing information.
Information provided by traveller information services must be immediately beneficial to the user in making travel decisions. Advising travellers through a variable message sign that there is “Congestion Ahead” on the network has little value if not supplemented by information on location, extent, and severity of the congestion and potential alternate actions.
It is important to maintain the accuracy of the information provided. For example, VMS which frequently show incorrect or no information will lose the trust of road users. This will defeat the whole purpose of the system. To ensure accuracy the issue of interconnections between the various centres must be addressed, if they are separate either in terms of the services that they provide or their locations. The seamless integration of information exchange between various centres becomes a major issue. This requires the adoption of a standard for data exchange and cooperation between the various players.
Though there is significant private sector involvement in many examples of traveller information services, the commercialisation of traveller information for profit is variable. Traveller information services that have been financially successful have generally involved packaging traveller information along with other information. (See Location Based Services)
For traveller information services to be successful, they must be marketed to potential users on a continuous basis. This marketing should be tailored to various market segments (such as road users, transit users). Successful traveller information services also seek customer input on services offered and are responsive to feedback received. For example, VICS of Japan continually solicit user requests and demand through the Internet, in order to better accommodate their needs.
Though not widely provided at the moment, users are interested not only in real-time information on network conditions but also in predicted conditions (for example: “a key junction is currently uncongested, but if the current trend continues, what will conditions be when I reach the location in 30 minutes?”). This will be the next important development in traveller information services.
Information transmitted must be adapted to the expectations of recipients so it can be used effectively. The information must be clear, understandable and useful to end users. Information that reaches its recipient is the end result of any initiative that answers the following questions:
Is the information accurate? The facts to be conveyed must be accurate or all credibility with partners/users will be lost.
Why provide information? Dissemination of information reflects intent by a operator that must be specifically defined – for example:
Who should be informed? The targets for information may be police forces, other road operators, local or national media and the road users themselves. Who should be informaed will vary acording to:
When should information be provided? Information about a current event is of interest to a recipient/users only if the users have it in real time. Choosing the time to send information about a planned event is not easy. This must be done early enough to allow for a response (especially if the operator expects cooperation from partners) but not so soon that it will be forgotten.
Where should information be provided? The destination of information (for example at a control centre, TV and radio stations, emergency servcies or a service provide) is defined by the network operations strategy and will be an integral part of operations planning. (See Planning and Reporting)
How should information be delivered? The information medium (social media, text message, Intenet, telephone, radio, e-mail, VMS’s, leaflets) is also determined by what is most cost-effective and the available resources. (See Traveller Services)
How should information be presented? Each recipient or group of recipients must receive the information in a personally tailored format. If there is a common language (event nomenclature, location, etc.), a message drafted in technical or even coded terms may be understood by a partner. To be legible by a partner, that message must not be buried in a lot of irrelevant details. For example:
Messages to users must follow the guidelines below:
It is usually very practical to use forms for exchanging information that has been defined in advance with the partners in question. Where they exist, standards for data exchange should be used.
Communicating is as much of an art as operating the road network. Network operators should:
Disseminating information to users entails drawbacks and constraints:
Road Network Operators and other transport or public safety professional have no direct control over road users (except, perhaps, at traffic signals). Each road user is an independent entity that observes situations from the perspective of his or her specific needs, does their own thinking and decision making and executes their decisions more or less independently. The only thing the transport profession can do is to inform the travellers in the best possible manner to enable them to make informed – and hopefully safe – decisions. (See Traveller Information Systems )
A survey by Florida DOT District 6 (Miami-Dade Co. and south) found that 92% of freeway/turnpike drivers read VMSs at least weekly, 97% said these signs provide accurate traffic alerts, and 78% reported a willingness to alter their route based on VMS postings. Use of 511 increased in the past year and 22% of respondents were more willing to change their departure time as a result of 511 information.
(Source: Rodriquez, J., “Miami Drivers Reported Travel Benefits from Using Dynamic Message Signs,” SunGuide® Disseminator, Florida DOT, January 2013.)
Advanced Traveller Information Systems, or ATIS are designed to support individual decision-making. The goal of ATIS is for travellers to have information at their disposal to help them make better-informed travel decisions about mode, route, departure time and activity choices. A side effect of these better decisions can often be supportive of efficient and safe traffic operations.
There is a full range of advanced traveller information provider systems and services. A summary is given in th table below along with advantages and disadvantages (in no particular order):
Technology |
Advantages |
Disadvantages |
Posting of messages on VMSs |
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Posting of messages on PDMSs |
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511 (voice, automated) |
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Call taker |
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Website (TCC or 511) |
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Media – radio traffic reports |
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Media – TV traffic reports |
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Airborne spotting and reporting |
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Kiosks and display signs |
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In recent years, the proliferation of smartphones and other mobile devices (such as digital tablets and pads), the expanding use of social media and the increasingly wide-spread use of Floating Vehicle Data collection techniques have led to a number of truly advanced traveller information services. Some services collect data to be used by other traveller information providers.The Table below summarises these.
Technology |
Advantages |
Disadvantages |
Point (that is, fixed location) data collection systems |
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Floating (probe) vehicle tracking |
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Commercial traveller information services |
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Social media – situation reporting |
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E-mail alerts |
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In-vehicle telematics (including personal navigation devices) |
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VMS and Highway Advisory Radio (HAR) are used to alert rural travellers in mountainous areas about weather and other conditions on the roadway ahead.
On long-distance or international trips, applications like those mentioned above (as applicable) or kiosks at rest areas, can help these long-distance travellers either adjust their trip plans or at least have a more secure feeling about their trips. (See Kiosks)
Traveller information in the other modes can do such things as inform public transport passengers of the arrival of the next vehicle and provide transfer information. Whilst these do not directly impact traffic operations at that time, this type of traveller information makes travellers more comfortable and confident about using public transport, thereby encouraging them to continue to do so and not add to clogging the roadways with more cars. Some Integrated Corridor Management (ICM) concepts include public transport as well, particularly Bus Rapid Transit (BRT) systems.
Traveller information can also provide information that does not directly affect current travel, but serves other purposes, such as safety messages, smog alerts and for child-kidnapping alerts. Note that there is some debate about the use of VMSs and HAR for non-mission-critical purposes. (See En-route Information)
There is a great deal of potential benefit that can be derived from using third-party data services (for example, real-time journey times on VMS, website traffic information, conducting historical analyses and so on). A number of commercial traffic Independent Service Providers (ISPs) provide services to both individual travellers and businesses as follows:
Further information: See Travel Information Systems and Traveller Services
Variable Message Signs (VMS) are capable of displaying pre-defined or freely programmable messages which can be changed remotely with individual pixel control. They consist of:
A Dynamic Message Sign (DMS) is any sign or graphics board that can change the message (text or pictogram) conveyed to the viewer. It may be either a Variable Message Sign (VMS) or a Changeable Message Sign (CMS) where:
See Roadside DMS
Roadside and overhead VMS are a basic traffic management tool for road owners and authorities – to provide information and advice to drivers and riders independent of any in-vehicle systems. In some cases VMS signs can replace fixed roadside signs to inform drivers of speed limits – if necessary with the flexibility of changing mandatory speed limits in response to traffic or road conditions where the legislation allows.
Research evidence shows that road user acceptance and compliance is substantially increased when the reason for a new, lower than normal, speed limit is displayed on the VMS in addition to the prevailing speed limit.
VMS can be used to convey maximum advisory (non-mandatory) speeds — to advise drivers and riders to slow down in fog, high winds and icy conditions or on the approach to an incident or slow-moving traffic ahead.
Evaluation of an icy road surface warning system installed on a mountain road in California indicated that, when the warnings of icy conditions were activated, mean speeds were more than 5 mph (8 km/h) lower than when no warnings were shown (Veneziano and Ye, 2011). In specific situations where ice was present but not likely to be expected by drivers (such as cold, clear and not-dry conditions), the reduction in speed was somewhat less — under 3 mph to around 3 mph (4.8 km/h). The speed data was collected at the VMS sign – rather than in the subsequent curve where the driver response may have been greater.
A fog-warning system on the A16 in the Netherlands had two levels of lower speed limit available, depending on the level of visibility. It was found that when the system was activated, average speeds decreased by 9-10 km/h. When the very low visibility speed limit was displayed, average speeds were higher than appropriate for the road conditions indicating that the advisory speed limit of 60 km/h was not low enough to influence driver behaviour sufficiently.
Dynamic management of speed limits in response to traffic flows has been shown to reduce speed variability and smooth flows, reduce numbers of accidents and increase overall throughput. It also has environmental benefits through the reduction of emissions. It is mainly applied on motorways. When used in construction zones or for temporary narrow lanes, the safety impacts are considerable, particularly as regards the protection of roadside workers. Dynamic speed limits are often combined with camera-based speed enforcement. (See Work Zones)
Roadside VMS is commonly used, particularly on urban roads, to inform drivers that they are speeding in the hope of encouraging them to slow down. These VMS are linked to speed detectors. When triggered by a speeding vehicle they display the speed limit or a message such as “Slow down”. The devices can also be mounted on a trailer for portability – for use, for example, in work zones. Portable Dynamic Message Signs (PDMS) have been shown to have an effect on the proportion of drivers speeding and on average traffic speeds. Some of that impact may be a novelty effect — since few evaluations have looked at the persistence of changes.
“Smart” or “Managed” motorways are becoming more common as a means of managing high traffic flows on motorways. (See for example http://www.highways.gov.uk/our-road-network/managing-our-roads/improving-our-network/smart-motorways/).
Typically, as traffic builds up towards the critical 2,000 vehicle per lane per hour, speed limits are reduced. The aim is to reduce speed variance and shock waves caused by traffic slowing down and speeding up - which can lead to incidents and accidents. The overall objective is to maintain traffic throughput - but the schemes have also brought about reductions in accidents and secondary incidents. Speed limits are enforced with automatic camera-based technology (time over distance cameras in the more recent schemes). Another common feature is the use of the hard shoulder for traffic at times of high congestion (“hard shoulder running”) with appropriate VMS signing. (See Case Study: Active Traffic Management Pilot M42 (UK))
National and regional standards are likely to apply to the design and installation of VMS. There are also applicable international standards for regulatory signs. Sixty three countries across the world have ratified the Vienna Convention on Road Signs and Signals. This states that road signs conveyed on VMS should generally conform to the text and symbols used on standard road signs. The Convention allows variations in colour in the interests of legibility. For example, it permits the use of dark text on a light background (the norm for speed signs) to be replaced by light text on dark background in the case of VMS - although the border must remain red.