VARIABLE MESSAGE SIGNS

Transcription

1 VARIABLE MESSAGE SIGNS Index Purpose Description Relevance for Large Scale Events Options Technologies Impacts Integration potential Implementation Best Cases and Examples 1 of 10

2 Purpose Variable Message Signs (VMS) are used to provide drivers with real-time information (which may be mandatory or advisory) relating to situations affecting the road ahead or in the immediate vicinity. One of the most common uses is to warn of congestion or incidents ahead (e.g. an accident, road works) which may lead to delays. VMS are also employed to indicate the need to change lane. If alternative routes exist, they may also offer routing advice. When there is heavy traffic on motorways, they can be used to smooth traffic flows and avoid congestion by displaying a recommended speed for each lane. In urban areas, in addition to congestion warnings, VMS are often used to provide information about road closures, parking availability, current events and other information which will help the driver select the most appropriate route. Description VMS are digital road signs which are located either on the roadside or on gantries above the carriageway. When connected to a Traffic Management Centre (TMC) via a local network or a radio link, they can be used as an integral part of the traffic management strategy. The messages may be composed manually or automatically. In the latter case, the VMS will be linked to a monitoring system and special software which analyses the data and actuates the display of a pre-set message when given circumstances are identified. The data used as a basis for the VMS may come from a range of sources, including roadside sensing systems (e.g. inductive loops, CCTV) or from organizations such as: Road operators Road maintenance agencies; The police Weather centers These bodies must transmit the information to be displayed on the VMS in an agreed and pre-coded form by means of a one-to-one communication link, a local network or radio communication. The signs themselves range from simple panels with one or two lines of text to large displays that can include graphical icons and, on a multi-lane road give different information for each lane. The composition of the message must comply with a set of recommendations regarding the number of characters, dimension, contrast and viewing angle. Messages must be easily and rapidly comprehensible to drivers. 2 of 10

3 VMS on a motorway Relevance for Large Scale Events VMS are extremely useful tools for large events as they are able to make available real-time information to motorists. When sited at key points on the road network, e.g. on the approach roads and motorways to a host city and event venues, they can help to guide vehicles away from critical or congested parts of the network and get them to their desired destination more efficiently. They can also communicate eventrelated information. Given the high cost of overhead gantries, it is likely that mobile VMS will provide a more practical solution in many cases. Potential uses of VMS during large events include the display of: Information relevant to route choice (e.g. road closures, accident, risk of delay, suggested alternative routes); Information about events (starting time, location, programmers changes, etc) Recommended parking areas (for Park & Ride) Information about public transport (e.g. in vicinity of Park & Ride sites); Warning of current or expected congestion; Information about special Meteorological conditions (especially for winter events) snow, ice, slippery roads. Options: description of variations available The main types of VMS are as follows: Overhead message panels mounted on gantries (typical on motorways and used to give traffic information, speed recommendations and emergency messages) 3 of 10

4 Examples of danger warning messages (FIVE framework) Roadside message panels mounted on the verge (these are normally used in urban areas for similar purposes as the overhead gantry) Parking Guidance Signs (message panel whose purpose is to guide drivers to ) Mobile message panels (these are mounted on vehicles or trailers and used on main roads or motorways to warn about temporary events such as accidents or road works) Mobile foldable trailer with VMS Mobile VMS - open Images by courtesy of Futurit GmbH VAS: Vehicle Activated Sign (signs which detect passing vehicles and provide warnings e.g. to drivers who are speeding) 4 of 10

5 Technologies VMS normally employ three general types of technology (IHT, 1997): Electro-Mechanical signs involve rotating planks with two faces or prisms with three faces which are usually used to give versatility to a standard fixed-face traffic sign. Reflective flip-disk signs are made up of a matrix of disks, one side black, the other fluorescent. The momentary application of an electrical current will magnetically flip a disk between the on and off states. These signs are well suited to showing combinations of letters or symbols as a message. Light emitting signs normally use fibre-optic, magnetic flip disc or light-emitting diode (LED) technologies. The major advantage of these signs is that a greater range of message can be displayed than for reflective technology signs. LEDs, being solid-state devices, can also produce very good reliability with minimal maintenance. More recent developments include: Liquid Crystal Displays (LCD), matrix band, liquid dot matrix and micro shutter technologies (ERTICO, 1998). It is feasible to combine technologies within the same sign. When used as warning signs, they are normally fitted with amber-flashing lanterns. The management of the VMS requires an operator interface, such as the COMPASS system illustrated below, which is a web-based system. By courtesy of MIZAR Automazione. The software enables an operator to compose a message (including icons), and pre-set messages to be displayed when a given event or traffic conditions are detected by the traffic monitoring system. 5 of 10

6 Impacts The principal impact of VMS is on traffic efficiency, which is achieved as a result of speed recommendations and congestion reduction. This has secondary benefits for the environment as a result of reduced fuel consumption and reduced emissions. Travelers also benefits through reduced travel time (by avoiding congestion) and through reduced stress (e.g. when travelling to an airport, motorists know they will be informed in advance if there are problems ahead, and take mitigating action). CRITERION IMPACT LEVEL COMMENTS MEASURED IMPACTS TRAFFIC EFFICIENCY *** VMS have a positive impact on traffic efficiency by smoothing traffic flows and helping drivers to avoid congestion. PT EFFICIENCY ** Street use management based on VMS technology can benefit PT efficiency, increased regularity of bus services and reducing journey time. Barcelona - 12/15% travel time MODAL SHIFT * When information is displayed on Park & Ride facilities or at bus stops, use of public transport may be encouraged. AIR POLLUTION ** The smoothing of traffic flows and reduction of congestion can lead to reduced fuel consumption and emissions. SAFETY ** Advance warning of accidents and traffic queues ahead (especially on motorways) can result in early braking and reduce the risk of head-to-tail collisions. [*, ** or *** indicate the strength of the impact] 6 of 10

7 Integration potential The effectiveness of VMS as part of the traffic management strategy is greatly increased when they are integrated with other ITS, for example: On motorways: Motorway Management Centre Roadside sensing systems Meteorological service In urban areas: Traffic Management System Parking Management System Overall supervisor for urban transport (high level management platform) Implementation VMS must be able to convey correct information in a timely manner and a form that drivers can understand and assimilate quickly. Road agencies need to comply with the specific recommendations and conventions regarding their location and content. Visibility Distance Legibility Distance Detection Reading and Decision Out-of-Vision A B C D M Θ VMS Detection, Reading, Decision, and Out-of-Vision Relationships of a VMS The viewing distance coupled with the driving speed dictate the amount of time available to read a message. For example, a motorist traveling at a speed of 120 km/h the message viewing distance necessary to read a message with 1, 2, 3, and 4 units of information is 60m, 120m, 200m and 270m, respectively, while at a speed of 55 km/h these distances are 35m, 60m, 90m, and 115m. (See report D2.3.1 of the SAFESPOT project). 7 of 10

8 The costs of the VMS itself are made up of purchase, operating and maintenance. They vary considerably according to the types of sign and complexity of the system within which it is integrated, e.g. need for sensing systems to provide information. It was estimated in 2009 the UK that the purchase and installation for 12 VMS is around 500,000. Examples case studies describing use of the tool: a) in previous large scale events Winter Olympics Torino 2006 During the Winter Olympics in Torino, VMS were a key element in the traffic management strategy. They were used in two ways: Large overhead VMS sited on all major entry routes to the city to provide general traffic information including routing advice for access to events and Park & Ride facilities (see illustration on next page) Small roadside panels on the approaches to the mountain venues used as part of the filter policy whereby motorists were advised in advance of the availability of the nearest car parking spaces to the event venues. (For further details see Past events/ Torino 2006) F iltro p e rm a n e n te F iltro v a ria b ile P a rk & R id e O ly m p ic F a m ily Tra n sp ort H u b VMS used to support the traffic filter system during Torino 2006 Winter Olympics 8 of 10

9 VMS on approach roads to the City of Turinused as support to the traffic management strategy b) in other more general contexts Multi use lanes, Barcelona To reduce the effects of increasing traffic in the commercial centre of Barcelona, the municipality has implemented new street use management based on VMS technology. Seven multifunctional lanes exist today in Barcelona on major boulevard of the Ensancheneighbourhood and they are used form 8,00 to 10,00 and from 17,00 to 21,00 (i.e. during rush hours) for general or bus traffic and from 10,00 to 17,00 for deliveries. Finally from 21,00 to 8,00 lanes are available for residents car parking. VMS display the access rights per user group in real time. Technically, the approach is realised in such a way that a first VMS shows whether the lane is dedicated to general traffic or parking/loading activities and, if the lane is dedicated to parking or loading activities, a second VMS shows the actual allowance for particular user group. 9 of 10

10 VMS in Barcelona The multi-use lanes are successful to optimise the use of the street space and improve traffic efficiency, especially for public buses: a reduction of between 12-15% in travel time has been registered. 8 7 Temps de Recorregut [minuts] :00 9:00 10:00 11:00 12:00 13:00 14:00 Hora Inici Recorregut Sense Carril Multiús Amb Carril Travel time changes along the Travessera de Gracia before and after the Multi use lane implementation SIRIUS VMS SIRIUS Information System for an Understandable Network for the User is the information and traffic management system of the Ile-de-France region. The System is based on real time data collection and advanced traffic management on the motorways and is able to cooperate with the City of Paris s IPER system, on surface arterials and the Boulevard Peripherique. The system provides comprehensive traffic information to the drivers through Variable Message Signs, over than 150 VMS under operation, placed before the motorway junctions or exits on the network. The information provided include incidents alerts and link travel time estimates and are made available by contract to private operators (e.g. for on-board traffic information services via Radio Data System Traffic Management Channel). The system is designed to manage the heavily congested road network in the Ile-de-France region improving users comfort by keeping them better informed, optimising the network s capacity and reducing the number of accidents (in particular tail-back accidents). 10 of 10