Taxonomy and description
Conventional signs and markings are visual means of providing information, guidance and instruction to travellers whilst en route. Their objective in the main is to promote the safe and efficient use of the transport system. As such, their design must be good and their maintenance given priority. Highway authorities have continuous maintenance programmes with contingency plans for areas susceptible to fog, ice and snow.
The word ‘conventional’ is used to distinguish types of signs and markings which have been used for many years from more modern types. Thus ‘signs’ in this case are taken to be roadside fixed signs with painted text or symbols: other types, such as Variable Message Signs (VMS) are dealt with in a separate section. Markings are lines and other symbols which are painted on the road surface or close to it (e.g. on the kerb). Both may impart information but both are often also concerned with managing traffic. For convenience they are dealt with together here under the general heading ‘information measures’.
Signs and markings are a vital component of almost every traffic management scheme and, as an intrinsic part of a design, they must be considered at the same time as the physical components of a scheme, and not added afterwards. In many cases signs and markings are complementary to each other, e.g. parking yellow lines and accompanying signs indicating the related regulations. Markings on the road can often be seen when vertical signs are rendered less visible by poor visibility and, conversely, vertical signs may be seen in some cases when road markings are obscured by snow or ice.
The messages conveyed by signs and markings should be as clear and concise as possible as they will generally need to be seen, read, understood and acted upon in a relatively short period of time. To assist with this, many countries develop sets of standard types of signs and, under the Vienna convention (1968), most countries throughout Europe have adopted a similar style of sign to facilitate a general understanding wherever travellers might be in Europe. However, information on the impacts of signs and lining is particularly limited at present.
Types of signing and marking
1. upright signs - various types of upright signs with textual or graphical images, divided into three main types:
• Information signs – giving information about routes and directions, distances, places and facilities of particular interest;
• Regulatory signs – giving notice of restrictions or prohibitions on the speed, movement and waiting times for vehicles;
• Warning signs – giving warning of hazards ahead.
2. Road markings – provided to channel traffic and to convey warnings,
regulatory requirements or basic information, they are sometimes supplemented
by studs incorporating reflectors; most are white but yellow is widely
used (in the UK at least) for markings related to parking and other colours
are increasingly used, including red (e.g. London’s ‘Red Routes’)
and green (e.g. Edinburgh ‘Greenways’). Road markings convey
regulations, guidance or warnings mainly, but not exclusively, in the
3. Miscellaneous signs – including traffic signals, temporary signs associated with, for example, special events or road works, flashing beacons to provide additional warning, cones to define routes around obstacles or road works, cylinders to denote the temporary division of a carriageway, and lamps to identify refuges or provide additional warning in cases of dangerous obstructions.
The circumstances in which these different signs and markings are permitted or required to be used is, for the UK, set out in the Road Signs Regulations and General Directions (RSRGD), most recently updated in 2002. In general, all signs on the highway must conform to government guidelines relating to their location, size, colour, the information provided and reflectivity, though there are circumstances when special signs might be approved directly by the Minister.
Common standards for signs and markings exist to help ensure that travellers can easily understand signs wherever they might be travelling. Where signs do not conform to the appropriate regulations, or where they are unauthorised, road users may be distracted, endangering road safety.
Variable message signs (VMS) are a further set of signs, using electronics technology to provide updatable information, and are dealt with separately due to their different character. Furthermore, traffic signals are another means of conveying messages and again they are dealt with separately owing to their different character.
In addition to roadside signs and signals, further information is increasingly being provided in-vehicle either by the radio, via Radio Data Systems (RDS) or via on-board units (OBUs). For the future, there are likely to be linkages between roadside information and in-vehicle information, e.g. speed limit reminders or even enforcement in association with electronic speed limiters.
Signs and markings are relatively low-tech facilities. Upright signs usually consist of a legend – text, diagram or symbol, picture or some combination of these - carried by a sign face which may be of sheet or other applied material (e.g. paint or print) mounted on a substrate – usually made from aluminium - and fixed to a frame and supported by a post or posts. Other types of miscellaneous signs are generally of a more simple construction and self supporting. In the UK, British Standard BS873 lays down the performance requirements for the various elements of road traffic signs.
Specialist computer software is available to assist with sign design,
route planning, location plans, manufacturing, signs inventory and maintenance.