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Sumit Singhal
Sumit Singhal loves modern architecture. He comes from a family of builders who have built more than 20 projects in the last ten years near Delhi in India. He has recently started writing about the architectural projects that catch his imagination. Lorient-Bretagne Sud Railway Station in France by AREPOctober 25th, 2018 by Sumit Singhal
Article source: AREP The extension of the high-speed rail line to Brittany will soon allow a three-hour total travel time between Lorient and Paris. The new high-speed line along with a more frequent regional rail service (TER) and the introduction of bus rapid transit systems will enhance the network, thus increasing passenger flows throughout the station, which is expected to handle 2.5 million passengers throughout 2017 (compared to 1.5 million until recently). Alongside the increase in ridership, the surrounding neighbourhood has undergone a thorough transformation, which led to the reconfiguration of the site layout. The formerly abandoned rail land has been redeveloped in order to host a new urban project and brand-new public spaces. The new station has been designed to form a link between the various districts and to integrate into the local context more successfully while providing enhanced accessibility the transport network.  Image Courtesy © D. Boy de la Tour
 Image Courtesy © D. Boy de la Tour
 Image Courtesy © D. Boy de la Tour  Image Courtesy © D. Boy de la Tour Enabling Urban Connections Through Inter-Modality The former station building was located to the north of the rail tracks, turning its back on the city and principal passenger flows. The new building, situated to the south of the rail tracks, lies in the heart of the transport interchange hub, which encompasses the rail network, coach stations accommodating intercity and regional connections, park-andride facilities, and secure cycle parking facilities. This dramatic shift in the urban landscape has turned the station into a high-profile public facility that occupies a key city area. Opening both to the ocean and the city centre, the building constitutes a new gateway to the entire conurbation and beyond, to the Île de Groix. To the south, the interchange hub is comprised of the main passenger building, the new coach station, car park facilities and the new TER platform, which is directly connected to the station – the nexus of the new neighbourhood. To the north, the former station building made way for a small building accommodating a secondary access point, operational premises, and passenger services. The forecourt has been refurbished to accommodate taxi ranks and drop-off points, cycle parking facilities as well as a long-stay car park… The large pedestrian bridge is a key element of the project: it links the two buildings and allows access to the platforms while ensuring the continuity of pedestrian movement between the north and south sides of the tracks and between the historic district of Kerentrech and the city centre. The station has the capacity to handle the 2.5 million travellers expected to pass through its doors with two additional high-speed trains (TGV) and a total of nine high-speed rail connections and 48 intercity connections every day.  Image Courtesy © D. Boy de la Tour The Passenger Building: An Imposing Public Building Within The City The main building, which lies to the south of the rail tracks, combines two adjoining spaces accommodating rail services on the east side and tertiary industry facilities on the west side. The multifunctional programme has seamlessly brought together retail outlets on the ground floor, reception areas and inter-modal information mediums, ticketing facilities, postal services and SNCF offices, thus transforming the station into a veritable service hub incorporated into an imposing building. The identity of the passenger building and the components of the interchange hub draw on the local architectural vocabulary, inspired both by sea and land elements. – The ultra-high performance fibre-reinforced concrete (UHPFRC) shade screens on the façade, the background colour, the stone and granite flooring allude to the built heritage of the city and pay tribute to Lorient’s stone and concrete architecture – of the post-war Reconstruction era, in particular – and to long-standing local schemes aiming to develop and highlight the built heritage, its ornamental features and subtle colours. – The form and materials allude also to the sea with the main building bringing to mind a vessel that can be accessed from the platforms via the pedestrian bridge acting as a pier, and the main structural elements and the sidings made of timber. The steel railings and assembly parts borrow elements from ship deck design.  Image Courtesy © D. Boy de la Tour The design gives prominence to timber as it is an environmentally responsible choice and a sustainable material creating a warm atmosphere. It was used for the construction of the fine and sophisticated frame in order to create a noble, legible, welcoming, and reassuring public space. The station echoes the surrounding seascape, and this is particularly true for travellers coming from Paris, who, even before their arrival at the station, can see the shipyards in the distance from the bridge overlooking the Scorf estuary.  Image Courtesy © D. Boy de la Tour The Passenger Building: Featuring A Timber Concourse The concourse The new passenger building, vast timber shed next to which highspeed trains stop, echoes the fluid forms of ship hulls and revisits the shape of the tuna boats from the Île de Groix. The shed is extended by a canopy supported by the main, trident-like, structural element, whose implementation required bold initiatives. Its 12-metre high, Douglas-fir laminated timber frame supports the four half-portal frames and the roof topping the main entrance, which cantilevers over 20 metres to create a vast porch that becomes the very expression of a welcoming place and of Lorient’s intermodal transport. The roof The double-curved roof matches the supple form of the building and forms a fifth façade that can be seen from the tallest buildings – evoking lighthouses – of the Odyssée special planning district (ZAC).  Image Courtesy © D. Boy de la Tour The façades The south façade features timber panels that provide thermal insulation. The rainscreen cladding prevents water from penetrating into the wall construction. Its red tint, visible through the protective screen walls, evokes the range of colours used during Lorient’s Reconstruction era. The ultra-high performance fibre-reinforced concrete (UHPFRC) screen wall gives the building consistency and importance and acts as a shade screen sheltering the openings accommodating the various elements of the building, such as the main hall, retail outlets, offices and services. The north façade extends to shelter the entrance from the wind. Fully glazed, it allows sweeping views of the platforms and the trains from the concourse and of the district of Kerentrech from the station and the city centre. It expands towards the linear canopy of the coach station. The east façade has been mainly designed to allow the station to remain inaccessible during the closing hours and to shelter users from bad weather. A simple glass screen supported by cable-stayed masts separates the concourse from the canopy.  Image Courtesy © D. Boy de la Tour The pedestrian bridge The 60-metre long and 7-metre wide pedestrian bridge consists of two spans rising seven metres above the tracks and allows both to cross over the tracks and to access the platforms, while providing a pedestrian connection between the city centre and the northern district of Kerentrech. The pedestrian bridge leads directly into the concourse, thus contributing to the station’s everyday use and function. The timber superstructure of the spans is composed of 40-cm high beams completed by fine metal diagonal ties forming triangular units, a construction choice that results in a transparent and lightweight structure. The route provision is sheltered and legible and the view of both the station and the city promotes a reassuring environment for travellers.  Image Courtesy © D. Boy de la Tour The forecourt The north and south forecourts give prominence to soft modes of transport – pedestrian movements and bicycles – and accommodate drop-off points, taxi ranks and cycle parking facilities. The new intercity coach station lies on one side of the passenger hall and unravels like a ribbon between the already existing coach station, located at Cours de Chazelles, and the canopy of the passenger building. It forms a gallery connecting coaches, buses and trains.  Image Courtesy © D. Boy de la Tour Techniques Of Construction The Passenger Building: Featuring A Timber Concourse The timber frame The Douglas-fir timber frame is fixed on a set of concrete posts, beams and floors that ensure stability. The main structure is composed of 23 portal frames made of Douglas-fir laminated timber having a span of between 12 and 19 metres and a height of 13 metres. The stress in the braces is distributed across the frame over a length of 113 metres through the timber and metal roof plan. Thereby, neither the fully transparent north façade that opens onto the platforms, nor the south hall façade need any triangular elements. The portal frames are composed of posts and beams whose varying cross-sections depend on the internal stress, and of rib-like profiled sections describing a continuous form. The four half-portal frames which are perpendicular to the canopy are supported by the tridentlike main structural element. The embedded fastening elements have platinum ends that are incorporated into the timber beams. The roof: Fifth façade and bracing The double-curved roof matches the supple form and outline of the building. The plan of the roof contributes to the overall bracing as the stress is transferred from the portal frames and the canopy towards the internal reinforced concrete structures. The purlins that are fitted on the portal frames support the timber panelling. The whole structure is braced by inserting single metal diagonals into the rectangular areas of a structural frame (triangulation). The underside of the roof in the 12-metre high concourse features a 5cm x 5cm spruce lattice supporting a sound-absorbing material aimed at minimising background noise levels to ensure that audio announcements are audible.  Image Courtesy © D. Boy de la Tour The south façade: A sheltered timbered façade The south façade features timber panels that provide thermal insulation. The floor-to-ceiling panels feature a 4.80-metre span between the beams (the same as the portal frame span), and openings corresponding to the windows of the operational premises and offices. The interior façade is covered with uncoated chipboard panels. A rainscreen cladding prevents water from penetrating into the exterior façade. Its red tint evokes the range of colours used during Lorient’s Reconstruction era. The rainscreen is protected by an ultra-high performance fibre-reinforced concrete (UHPFRC) screen wall which also reduces solar radiation. The north façade: A transparent façade on the platforms The fully transparent north façade was designed according to two principles: – The station façade features a steel frame and profile, as well as glazed openings. The concourse has no thermal insulation except for the waiting areas; – The façade of the office premises features an aluminium frame and profile, as well as double-glazing to comply with the 2012 thermal regulations. These self-supporting façades are fixed to the timber portal frames by steel bearings allowing adjustments and movements of the façades thanks to oblong holes.  Image Courtesy © D. Boy de la Tour The east façade There was practically no need for an east façade (the various types of transport means would have been better connected). However, the concourse needs both to remain inaccessible during the closing hours and provide shelter from bad weather. To this end, a simple glass screen separates the concourse from the canopy. Five cable-stayed masts rise from the ground. They are connected to each other at their base and are fixed to the portal frames by bearings. They support the glazed panels thanks to ties in order to avoid any horizontal or vertical profile and to attenuate the presence of the façade. The fastening devices at the top of the mast allow the frame to move.  Image Courtesy © D. Boy de la Tour The pedestrian bridge and access piers The pedestrian bridge leads directly into the station concourse and connects the city centre to the northern district of Kerentrech. It forms a horizontal link composed of two 18-metre spans. Each span is supported by metal portal frames and features a double Vierendeel girder made of Douglas-fir laminated timber. The chords and posts are thereby linked and embedded. The beams have been reinforced by metal diagonal ties having a 6-cm diameter so that chords can be the slimmest possible at a 40cm x 30cm height and the posts at a 30cm square section. This solution resulted in a transparent and lightweight structure and minimised the difference in height as the pedestrian bridge lies seven metres above the rail tracks. The lower chords and posts are covered with steel cladding and copings to protect the embedded fastening elements. The chords are protected by the overhanging deck, thus reinforcing the image of a lightweight and plane footbridge. The same materials have been used for the piers, which incorporate all the vertical circulations (stairs, escalators and lifts).  Image Courtesy © D. Boy de la Tour The platform shelters and the coach station The platform shelters are made of Douglas-fir timber according to a double-pole system in order to minimise spread footing. The roof is supported by tie beams featuring varying sections; they are linked by a central double beam which incorporates the eaves gutter. The tie beams cantilever from the Kalzip® double-sloped roof (the same material has been used for the station roof). The coach station shelter stretches out over 300 metres and forms a canopy supported by posts set every 4.80 metres. The glazed end of the canopy allows views of the station canopy. Flooring The floors of the pedestrian bridge and stairs are covered with 6-cm wide Moabi hardwood slats set on stringer beams, themselves resting on the structural purlins perpendicular to the wooden truss. Linear ribs ensure anti-slip flooring. The concourse floor and its extension on the forecourt are made of gravel-studded asphalt that features Huelgoat granite strips set every 4.80 metres. The asphalt, an industrial material often used in harbours and platforms, has been upgraded through sanding and stone insertion.  Image Courtesy © AREP  Image Courtesy © AREP
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