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Comparison between LRT vs AGT, costs & benefits

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Francis Kuhn
added 4 research items
L'exode des populations des régions rurales à la recherche d'un emploi et d'un plus haut niveau de vie a souvent donné une urbanisation, rapide, plus dense, dans les pays en voie de développement que, celle rencontrée dans la plupart des pays industriels. La croissance phénoménale des villes de São Paulo, Mexico, Le Caire atteste de ce haut niveau d'urbanisation. Les taux de motorisation qui s'accroissent de façon dramatique restent cependant encore loin derrière ceux des nations industrielles : ainsi s'ouvrent pour les transports publics de grands marchés, notamment pour le métro léger qui reste en compétition avec l'autobus. Nous essayons à travers les cas de Tunis, Manille et les projets de Curitiba, Salvador et Brasilia de décrire le choix des responsables de transports, qui s'est porté sur le métro léger pour résoudre les problèmes de saturation de la circulation.
Après une description géométrique et technique de 20 systèmes de transport urbain guidé exploités ou à l'étude en France, le présent rapport procède à une analyse comparative des coûts de construction en souterrain et en viaduc en fonction de différents paramètres de sols, de géométrie et de capacité. Cette comparaison est effectuée pour des interstations de 800 m et de 400 m c'est à dire d'un ouvrage en ligne et d'une station adaptés à chacun des 20 systèmes pour des capacités équivalentes de transport. Les coûts sont obtenus à partir de 2 logiciels de dimensionnement, les modèles METROV et ESTIM dont les notices sont jointes en annexe avec le bordereau des prix val. Jan. 92. Les méthodes de construction analysées sont la tranchée couverte superficielle, la tranchée couverte profonde, le tunnel réalisé au tunnelier et selon la méthode traditionnelle et le viaduc. L'intérêt de la construction d'un monotube ou d'un bitube pour réaliser un tunnel à 2 voies est examiné pour les principaux systèmes de transport. Une analyse des coûts de génie civil à la place offerte pour chacun des 20 systèmes complète la comparaison. Pour chacune des méthodes constructives la progression du coût de génie civil est examinée en fonction de l'augmentation de la section, des dimensions des ouvrages, c'est à dire de la largeur et de la hauteur des véhicules, le gabarit des véhicules retenus dans cette étude varie entre 1, 60 m et 2, 90 m , la longueur entre 3, 12 m et 312 m: l'étude montre le gain de coût possible si on optimise l'implantation des équipements fixes et on réduit les dimensions intérieures des ouvrages. En conclusion , cette étude nous montre qu'il y a de nombreux paramètres qui influent sur le coût de construction d'un souterrain, que la solution aérienne est la moins chère et que parmi les méthodes de construction de souterrain, la méthode au tunnelier peut s'avérer la moins chère au delà d'un certain linéaire d'ouvrage à réaliser: la solution bitube par rapport à une solution monotube selon les cas peut s'avérer la moins chère des deux types de construction.
This study tries to compare the Light rail transit with the Automated guided transit with some data of the Val's network in Lille and the Modern tramway in Nantes. Exclusive rights of way and priority at junctions improve the quality of service and capacity of a public transport system. These parameters will depend on the type and size of the public transport vehicle, the means used to establish right of way segregation and the degree of segregation in town centres. We present below four categories of right-of-way segregation used in the case of Light Rail : - exclusive right of way corresponding in general to new realisations in city centres on several levels : tunnels or viaducts. - segregated right of way corresponding to independent tracks in the middle of or along a boulevard or on a former railway track ; - reserved right of way corresponding to lanes of the carriageway in general delimited by paint or using specific surfacing, but not separated physically from general traffic ; - shared right of way composed of lanes of the carriageway used by general traffic : these tracks are found rather in old networks on carriageways with little traffic or on those too narrow to reserve a suitable space for the tramway. In this last type of site, we can classify the mixed pedestrian-public transport streets or Malls in which the carriageway is used only by pedestrians and passing tramways. The public transit systems running under " automatic integral control" have several main characteristics to run on segregated right of way that is to say separated of the general traffic being underground or on a viaduct, or on the surface behind high protective fences. This stress has an incidence on investment costs because the metro is built in dense zones of cities, there are few surface sites and the number of junctions is such that it is better to adopt either a viaduct where it is possible, or an underground more or less costly in relation to the geotechnical local conditions. Then we understand all the benefits of reduced geometrical size and very short headways : a comparative analysis comparing the civil engineering costs depending on the adopted transit systems done by INRETS in 1992 allowed us to verify that the construction costs are linked to the vehicles gauge of systems and that for an equivalent capacity, the civil engineering costs (tunnel and underground stations with the cut and cover method at a superficial level) of VAL 206 is lower by 8,4% to 16,9% than these of Light Rail for 7000 to 20000 pas./h/dir. capacities, with 60 seconds headways for the VAL and 90 seconds for the Light Rail. For a deep tunnelling construction carried out with a Tunnel Boring Machine (TBM), the differences of civil engineering costs of VAL 206 and Light Rail are between 17,3 to 31,4% less for the VAL 206 at 7000 to 20000 pas./h/dir. capacities.
Francis Kuhn
added 2 research items
The quality and attractiveness of urban public transport has been improved by several technological innovations over the past twenty years. Operating conditions have been transformed, with improved safety and flexibility; adaptation to the needs of passengers and operators can be ensured owing to the possibilities offered by automation. Light rail and automatic guided transit systems present intermediate characteristics between those of buses riding on shared right of way and those of conventional metros on segregated right of way, from the point of view of investment costs. In this paper, the two types of new transit systems operated in France for more than ten years: LRT and AGT are presented.
Since 1981, about twenty automatic urban transport of conventional type systems are under operation in actual urban centre services and several systems are planned or under construction (Turin, Lausanne). In all the cases, these are systems running on segregated right of way, fully automated, with quite different vehicle characteristics. The application of fully automated driverless operation to the new transit systems is the consequence of a research of technical performances (high speeds, reducing intervals between trains, increasing safety) not possible with manually operated trains. Indeed, at the peak hours on the urban metro of Paris and other networks in the world, most of the lines have been manually operated for twenty years yet automatically at least at peak hours, that is to say at those where operation must be the most efficient and where drivers would have to apply more concentration than humanly possible. The user benefits from the high frequency brought by full automation, avoiding long waiting times in station. This quality gives further attraction to public transport. In addition, this high frequency also can be obtained at off-peak hours by cutting trains between peak and off-peak hours which brings operation supplementary flexibility. High frequency of passage has another advantage on civil engineering costs of transit systems : at equal capacity the light rail (Grenoble type) running with 3 unit trains every 4 minutes offers a capacity of 7800 p/h/d, the AGT (VAL type) running with 1 unit train with an interval of 72 seconds offers a 8000 p/h/d1 capacity. In the first case the platform length is 90 m, in the second case the platform length is 26 m. The innovations brought to the traditional modes of transport system have greatly spurred the improvement of the networks productivity. The rapid progress of technologies linked to the electronics and computing leads to increased gains in productivity bestowing on the public transport networks a growing tendency to automation. The objectives to minimise the costs of a means of transport, adapted to a demand whose importance and structure normally justify a metro, all by giving to users a high service quality have permitted to define for Lille the small gauge of VAL's system, its short passing headway at the peak hour and the technical and economical necessity to conceive its automatic integral control. This type of driverless automation on board, has given place to particular technical solutions which would not be the same for other metros manually operated : ie. the landing doors on the platforms, the numerous redundancies of certain equipment items allowing to guaranty a very high availability without need of an immediate human intervention and the necessity to highly develop the means of monitoring and communication. April 1983 : the Lille subway opens for commercial operation. Experimental operation with the public had been going since April 1982. The VAL system, for which the LILLE SUBWAY constitutes the first application, is thus one of the first entirely automatic urban transport systems, that is to say, without any staff being permanently placed on the trains or in the stations.