The planning and design of main roads in the urban environment has been a constant part of MOPT activity, as well, more recently, as in the Autonomous Communities. The 1974 Ley de Carreteras recognises the importance of the Arterial Network and its planning as one of the basic activities connected with the study and design of main roads. The tradition of studying arterial networks, rather than isolated stretches of city access roads, goes back to the sixties and early seventies during this years numerous arterial schemes were developed, according to criteria obtaining at that time, and which have conditioned recent construction on main roads in the urban environment. More recently, the 1984-91 Plan General de Carreteras and the Main Road Plans of the Autonomous Communities have included Action Programmes in the Urban Environments covering the layout of new main roads as well as improvements to existing roads. Finally, the current Ley de Carreteras (25/1998), in Chapter IV, considers the issues of throughways and the Arterial Network. The increase in traffic on the road network, particularly in urban areas, justifies the spending of large sums of public resources on the construction of and improvements to State an Autonomous Community road networks. During the eighties investment was concentrated on the intercity network, specially on the MOPT Motorway Programme; in the nineties we face the challenge of improving urban networks and the intercity connections between intercity routes. In meeting this challenge we must give due attention to the multiple and complex factors which arise or can be affected by a city roadway layout. This means thinking not just about the functional traffic problems of vehicles, but also of all the urban aspects of the road, the physical impact of its layout, or the likely economic effects of better longitudinal access and the negative effects of restricted transverse access. All these factors have a strong effect on the design of an urban main road and make it impossible for design studies to be based exclusively on traffic and circulation requirements. The recommendations as summarised here are not intended to be an exhaustive manual for the planning and design of urban main roads. There are numerous text, listed in the bibliography of the recommendations, which completely answer any need for detailed planning and design information. Our intention here is to introduce new criteria, and to bring a new focus to bear on problems, methodologies or basic data which may help the designer in considerations of the particular case he is working on. The recommendation published in May 1992 are divided into five parts which may be read separately: A) Lays the foundations and coordinates for main road planning studies, their objectives, traffic analysis and analysis of the urban environment through which the road will run; B) Summarizes the urban main road planning and design process; C) Develops some partial elements of main road design; D) Studies the impacts of noise, air pollution and landscaping; E) Makes some general recommendations for the design of the two basis types of urban mam roads: continuous circulation roads (motorways, autovias and single carriageway urban expressway) and roads which allow interactions (arterial roads). The recommendations exclude secondary urban roads (collecting, distributing and local roads), in order to concentrate on main roads in the primary networks which are included in the total State Network and the main networks of the Autonomous Communities. In this document, which summarizes the one described above, the contents have been ordered into five chapters which cover first, questions referring to the planning of main roads in the urban environment, then the characteristics of the different types of roads to be considered; in the third and fourth chapters we set out the elements to be taken into consideration in the design of motorways, autovias and single carriageway urban expressways, and of arterial roads, which are not subject to the same degree of control of access; and in the last chapter we discuss issues of treatment of the environment and road safety, since improvement of these aspects must be of permanent concern to all those responsible for the planning, design and management of our main roads in general and specially when they pass through towns. (a)
Samenvatting