As we are fast-tracked into the Third – and digital – Industrial Revolution, we risk leaving behind (or even erasing) a great wealth of heritage infrastructure, now out-dated urban hardware that can have, nevertheless, invaluable architectural and historical merit and, more importantly, enormous urban potential.
Who has not felt a sense of wonder when admiring the monolithic efficiency of our towering factories, which rise like austere cathedrals over the suburban sky?
Instead of merely deleting our recent industrial past, we should, instead think, of creative ways of repurposing these structures to our communal benefit under new, post-industrial uses, instead of letting them rot like old Detroit car factories.
This proactive approach has already produced some notable examples of post-industrial new architecture – the most famous of which may be London’s Tate Modern art gallery, sited on a old red-brick coal fired power station – that have gone on to become fully recognizable urban icons.
One notable example of regenerative landscaping is New York’s High Line Park, which turned a disused and decrepit elevated old railroad into a snaking, hypnotic urban promenade, where urbanites can find refuge from the intense traffic happening below. Other examples of obsolete railway infrastructure turned over to the public realm can be seen in Paris (Promenade Plantée), Chicago (The 606), Toronto, (Beltline Trail), Sydney (The Goods Line), and Dallas (Klyde Warren Park), to mention just a few.
The Old Railway Bridge, a beautifully crafted wrought-iron railway structure, is a very similar opportunity, with the added distinctive quality of floating over still waters of the Daugava river.
It is just the right scale to be transformed into a pedestrian promenade that, through careful and subtle landscaping, can finally provide a walkable link to three previously unconnected central parts of the city: Old Riga, Zakusala Island, and the leafy suburb of Tornakalns.
Our proposal aims to restore this industrial structure to its former glory, while turning it into an extension of the parklands it connects to. Most importantly, it will be the catalyst to the transformation of Zakusala Island into a newly landscaped, fully active urban leisure area, where citizens will be able to take part in numerous outdoor events in the newly designed auditorium, against the spectacular backdrop of Old Riga and the Daugava river.
The Riga Central Railway Station renovation will follow three main different stages: refurbishment of the existing station and facilities, construction of new underground accesses to the platforms and urban overpasses and, finally, installation of the main ring-shaped roof over the platforms.
The new ring-shaped canopy consists of a 160m-diameter roof supported on 50 columns distributed around the central skylight. The roof forms an opaque ring with a central covered elliptical skylight that spans a maximum of 88m over 9 tracks and platforms. Both the ring and the central skylight structures will be made of steel trusses supported by slender steel columns. The ring will have trusses in several directions in order to provide enough stiffness to the whole structure in the horizontal plane.
The entire ring structure is expected to be very lightweight. Horizontal forces will not affect its stability – which will be provided by the columns themselves, which will be fixed at both foundation and roof levels. The remaining station and urban overpass works will be executed in reinforced concrete. Some slurry walls and horizontal micro piling will be considered for the construction of new overpasses without compromising the train operation.
The new railway bridge over the Daugava River has been designed to be as slender as possible and also to produce as little shadow as possible over the existing railway bridge. In order to do so, the number and length of spans matches the existing bridge’s number – with a maximum length of 87m.
The design allows for both regional and high-speed train platforms to be placed over the new bridge, over a maximum width of 28m, including double rail tracks (1435 and 1520mm gauges), catenary and services.
The bridge is designed as a continuous cable stayed bridge, spanning 87m and with only one cable per tower. The cable stay will divide the span in approximately one third of the length. The maximum height of the tower is expected to be around 10m above the bridge deck level.
The towers will be supported by columns resting on a large pile cap at the water level, and deep foundation into the riverbed. The V shaped columns will support the cable stay tower creating a certain eccentricity, which will require a horizontal tie. This tie will at the same time be used as a horizontal support for the continuous deck. Both piles, pile caps and columns are designed in reinforced concrete, while the cable stay tower is designed as a steel box.