Madrid's M-40 by-pass belt, which is 61.1 kilometres long, consists of two clearly distinct portions : the south-eat and north-west arches, 27 kilometres and 34 kilometres long, respectively. This presentation will use the north-west arch to illustrate how environmental factors, in their simplest form, can influence urban highway planning. First, a comparison is drawn between the northern and southern M-40 zones by highlighting the most appreciable differences in design resulting from the degree of urban development of its surroundings and the different moments at which they were conceived and planned, ending with a reference to the construction costs involved. Second, the most crucial questions are examined regarding the north-west arch as a result of urban development or environmental influences, and which can be broken down into the following four categories: The main junctions by highlighting the varied designs in keeping with functional needs and the surroundings, which means a wide range from the longest designs in use to others where, without reducing their capacity, all left-hand movements tend to gravitate, giving rise to four levels along the same vertical zone with high quality structural designs. Segment I of the Cierre Norte (the northern merger) where both roads overlap along a stretch of more then a kilometre in length, with a specially structured concept to keep damage to the surroundings to a minimum. Tunnels under Monte del Pardo with their specially environmentally-protected zone and which because of their measurements (over 200 m2 of excavated section), the features of the terrain they cross (sand with medium to low cohesion) and their construction procedure, are exceptional on an international level. Complementary palliative measures of environmental impact, mainly replanting vegetation and providing acoustic insulation. The presentation ends with a highlight on the economic repercussions that environmental influences have had with regards to the construction costs of the different segments that make up the M-40's Cierre Norte. (A)
Samenvatting