Graz Central Station Redeveloped by Zechner& Zechner
Graz central station, with 30,000travellers per day, is one of the most important transport hubs in Austria. Theincreasing importance of the transport hub in the future requires adaption ofthe complex at
the train station as well as theconnections to public transport within the city of Graz Graz Central Station2020 project, is therefore one of the biggest programmes of the last yearswithin the provincial
capital of Styria. On the city side, thetram lines were moved below ground and the entire station plaza was redesigned.On the side towards the platforms, the infrastructure facilities werereconfigured.
Especially the roofing depicts a veryimportant element of both these two packages of measures. A large projectingroof of over 3,000 m2 was constructed as part of the new tram station on thestation plaza.
The new roofing for the platforms covers anarea of approx. 4,500 m2. The projecting roof covering the Europaplatz wasalready completed in 2012. Zechner & Zechner has already won several awardsfor the
planning, including the World InfrastructureAward. The construction works at the station were completed in May 2015.
The existing platform roofing at Grazcentral station no longer met current infrastructure building requirements. Theroofs came from several different periods, and some were constructed astemporary
measures.
The quality of travelling by train is alsodetermined by the quality of entrances and exits. Surveys and rankingsconcerning train stations clearly present the customer’s preferences: secureand light
departure and arrival halls with enoughsupply of information where passengers can easily orientate themselves andspend their time while waiting for their connections. In the area of the islandplatforms,
architects Zechner & Zechner used theopportunity provided by the renovation of the rail tracks to enable a newreconstruction of the roof that exceeds the situation of conventional railwayplatform roofing
and provides an appealing counterpart tothe modernised and expanded station building and plaza.
By the areal connection of the three middlerailway platform roofs a roofed large-scale area is created to provide a betterweather protection and a more pleasant and generous perception of the space dueto
the height of 8 meters. As a result ofspans up to 40 meters, the central railways platforms remain unsupported apartfrom the central pylon, which poses a major criterion at the Central Station inGraz
since the width of the train platforms areonly allowed to be smaller than 9 meters. To provide the roofed areas withnatural light, the closed roof membrane is opened and covered with translucentmembranes
in the area between the two main pylons.This way, natural light can be provided in the zone where passengers spend timerather than at the rail tracks.
In the outer areas of the train platformsthe connected roof construction from the middle transition changes intotongue-shaped single platform roofs. This way, a wave-shaped image developswhich calmly
flows out towards the edges. The structureof the “Wave” symbolizes movement and emphasizes the drive of travelling bytrain.
From Concept to Realisation
At the very beginning, large-scaled roofingwith preferably few columns was requested. Out of static reasons, an archedbridge-like supporter would provide a bigger span and meet the previousrequests. To
avoid pairs of columns along the trainplatforms the main supporters meet each other on a central pylon and spreadlenticularly between the supporters. Thereby a V-shaped configuration of themain supporters
is generated which also improves theincidence of light over the fanlight membrane.
Constructional steelwork
Beams with two spans of over 40m each, archover the area between the tunnel stairs creating generous waiting areas,without columns. The solid, box-shaped main beams are mounted on reinforcedconcrete
composite columns. All beams have an archthat rises by approx. 5m over their span. The pairwise outwards tilted mainbeams are presented with adjustable section heights and are connected with eachother by
purlins made out of rectangular steeltubes300/300/16 mm.
The arched beams will be constructed assteel box girders, with seal welds, which will reach a height of 4m at theshoulders. One pair of main beams will be situated over each platform. Thedistance between
the beams will increase upwards, forming aV and producing a lens shaped gap between the pairs of beams that will be usedto provide illumination to the platforms.
The roof structure was designed as an3-dimensional framework. Special attention was paid to the supports for thesteel structure, which also has a serious impact on the fire safety.
Construction
The phased installation of the heavy steelconstruction during a continuously operating train station demanded a detailedconstruction phase and execution of construction work. Moreover, the fact thatthe
train platforms could not be roofedgradually and but rather had to have their construction cycle linked with thephased planning of the track construction complicated the installation. Therefore, the
concept was to deliver the heavy steelbeams in large pieces and weld them on-site.
Connecting points for the construction ofthe roof were already prepared in the steel works and therefore provided aneffective installation on-site which was important due to the limited time oftwo
weekends for the construction of eachrailway platform. The welding of each beam section lasted a week.
Until the beam pairs were able to supporteach other, auxiliary constructions were positioned to secure the beams andonly removed after the closure of the gap.
Develoment and surfaces
The roofing is formed by an aluminiumsystem, which is attached to a trapezoidal sheet. The bottom view isrepresented by aluminium bonded panels which cast a light “sky” due to theirslightly reflecting
surfaces. The lenticular fanlight openingbetween the beams is closed by an EFTE-membrane.
Besides the photometric demands concerningsufficient intensity of illumination in the staircase area it was required todevelop an efficient lighting system which would be easy to maintain and not gobeyond
the scope of low electricity costs. Thelighting concept plans linear LED-illuminants along the fanlight openings. Theluminaires appear as chains of pearls that support the arched configuration ofthe
supporters and provide smooth and planarlighting. The bottom views of the roofings are additionally illuminated byceiling washers. The slightly specular aluminium bonded panels reflect thelight. The
pylons are also marked with spotlights. Atthe base of the main beams, LED-spotlights are mounted that cast a bluish“moonlight” effect on the platform area which creates a distinctive ambience.
The decision to apply LED lighting hasclear economic advantages. In relation to the durability of the lamps alongwith the maintenance, the permanent use of LED technology constitutes an energysaving of
about 40 percent compared to conventionallamps and makes Graz Central Station the first European rail station with 100%LED lighting.
人行隧道联系各个站台。其中一条150 米长的隧道中墙面装饰采用了Peter Kogler 的作品。
A 150 meter artwork – the new Northernpedestrian tunnel:
In the Northern part of the platforms a newpedestrian tunnel was built up. The new passage connects the differentplatforms but also provides a connection to the district beyond the trainstation. The
length is alleviated by an appropriateconcept of the cross section and proper artificial lighting but especially thelarge-scale glass cladding, which is printed with one of Peter Kogler’sartworks and
transforms the 150 meters long pedestriantunnel into a unique exhibition hall. The wall depicts the sequel to theinstallation of 2003 inside the station hall which is also one of PeterKogler’s artworks.
Extension of the Southern tunnel
In the course of a reconfiguration of thetrack areas a new platform for local public transport was built on the westernedge of the field which can be reached via the existing Southern tunnel. TheSouthern
tunnel forms a central site development ofthe platforms when coming from the station hall. The extension has beendeveloped further to fit the style of the existing tunnel.
Fire protection and safety
The requirements concerning the fireresistance of the roofing pose a problematic scene. In contrast to other trainstations, trains run underneath the roofed tracks which therefore requested afire scenario
with 60 megawatt. According to themagisterial standards, a durability of the system for 30 minutes was to bedisclosed. In terms of the maintainability of building elements in the trackarea, no fire-proof
coating was to be used in accordance withthe standards of ÖBB.
In proof of the durability specialtemperature assessments were conducted for three fire scenarios. Simulatedtemperature profiles presenting over 1000 °C in the area of the columns andapexes provided a
base for the measurements. 33 minutes wasthe calculated time of resistance to collapse of the nonlinear supportingstructure. In case of impingement with a consistent temperature profile,the
supporting structure would even withstand atime span of 55 minutes.
In addition investigations concerning theaerodynamic loads affecting the roof structure and the passengers on theplatform due to air velocities and train-induced loads of air current andpressure were
carried out. Thereby the strains on thepassengers at the platforms should be reduced. The examinations showed advantagedaero dynamics due to the arch-shaped form of the roof. Disturbing train-inducedloads
of pressure are therefore not to beexpected.
Text:
Martin Zechner, Zechner & ZechnerZTGmbH
Details:
Client: ÖBB Infrastruktur AG
Architects: Zechner & Zechner ZTGmbH
Structural Planning: Steelwork:Zivilingenieurbüro Dr. Kratzer
Concrete construction: Rinderer &Partner ZTKEG
Transport planning and
overall coordination: Rinderer & Partner ZTKEG
Art within architecture (northtunnel): Peter Kogler
