Since the opening of the first HS lines in Europe, there has been an impressive progress in all fields of railways, whose most noticeable evidence -and benefit- is the progressive enhancement of commercial speed. These advancements have implied an increase in requirements’ exigency of not only track components but also in the associated civil works (mainly in tunnels and viaducts) leading to a completely new construction and maintenance procedures. COMSA is well-aware of the raising strictness of track tolerances given its continuous presence in HSL projects since the construction of the Spanish first HSL Madrid-Sevilla – more than 20 years ago. As a result, COMSA through its participation in more than 50 HS projects in Spain and Italy, has witnessed the strong development of technical specifications, to whose fulfilment its construction methods had to be adjusted.
From the civil works point of view it should be highlighted COMSA involvement in two important projects to name but a few: the Guadarrama Tunnel in the Madrid-Valladolid line and the Deza Viaduct in the Ourense-Santiago line.
The Guadarrama Tunnel, with its 28,4 km, became the third longest tunnel in Europe, only after the Gotthard Base Tunnel and the Eurotunnel. This monumental work site with and investment of 1,2 billion euros, meant 3 years of work and involved more thank 4000 people.
Guadarrama tunnel is composed of two twin tunnels separated 30 m between axis, and connected every 250 meters through emergency galleries. Both tunnels were constructed by four TBMs that bored a 9.5m face diameter, reaching an advance speed up to 1 km per month. The excavated material exceeded 4 milion m3, which would be enough to build 1,5 Cheops pyramids.
On the other hand, the Deza viaduct is located in one of the most challenging sections of the Ourense-Santiago line, the Lalín – Silleda section, where the layout had to deal with a beautiful but montanious landscape (36% of the section are viaducts and 37% are tunnels).
The Deza viaduct – located at the start of the section – is a stunning viaduct with a length of 1175 meters, a maximum span of 75m and with the higher piers reaching 96,5 meters. The key element of the bridge is the reinforced concrete central arch to overcome the Deza River, spanning 150 meters with a maximum height of 108 meters. The selected construction methodology included the construction of one half of the arch at each side and a later rotation to reach the final position. It is the highest rotated arch in Spain and one of the biggest in Europe. The budget of the section was 120M€.
Furthermore, a big leap forward has been done in track works during the last 20 years, both in terms of materials and track laying methodologies.
Initially, the first Spanish HS lines were entirely constituted of ballasted track and track assembling was carried out employing an auxiliary track, which limited the overall output. As the experience in HS construction increased, new developments were implemented in the lines that ensued, such as the inclusion of slab track in tunnels of considerable length or new designs for embankment-structure transitions. Referring to slab track used in tunnels, its design has also evolved through time and nowadays an optimized solution without steel reinforcement is being applied.
On the other hand, in Italy, COMSA had to abide to Roma-Napoli HSL specifications, which differed substantially from those relating to Spanish projects due, in part, to differences in track design –e.g. bituminous subballast placed under the ballast layer-. Track assembly methods employed in the construction of Roma-Napoli HSL varied from auxiliary track method with plat-off advancing system to Automatic Assembling Train (i.e. refurbished TRT), which was able to unload sleepers and rail and assembly them without requiring any auxiliary track
Later on, during Madrid-Valencia HSL construction, a new method for track laying was developed using caterpillar cranes and rollers to unload the rail, which made the auxiliary track unnecessary and led to an output heightening (up to 2160 m/day). Thereafter, subsequent HS projects, such as Ourense-Santiago HSL, have been constructed with this technique.
In what regards to maintenance, the opening of the firsts HS lines involved a new approach, based on preventive maintenance, in order to achieve the level of exigency demanded to track condition. The reason of such strict defects’ tolerances was not only due to the increase of defects’ influence in passenger comfort caused by dynamic effects, but also derived from the high reliability and quality of services to which HS trains were, strategically, associated.
Maintenance activities are undertaken by Contractor Companies, such as COMSA, which has developed a strict collaboration with Infrastructure Manager ADIF during the last 20 years. Heavy duty machinery and stocks of materials are hosted in Maintenance Bases, which are associated to a specific section of the line with the appropriated length, so works can be carried out during the tight night shift. Quality assessment of executed works is evaluated by ADIF on KPI’s basis.
As the length of the Spanish HS network increased, several improvements have been made in HS maintenance routines: Intervention thresholds have been modified accounting to track consolidation, periodicity of dynamic tests has been increased, speci-fic maintenances routines for recurrent hot-spots are developed, some Maintenance Bases have been merged in order to improve resources’ efficiency, length of maintenance contracts have been extended, etc.
In resume, due to its presence since the origins of HSL up to now, COMSA has actively participated in all the improvements that were required to increase speed, materials’ lifespan and cost-efficiency. that have enabled today’s railways.
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