Proximity to water, ground conditions and flood risks present particular challenges
A whole new infrastructure has been built for the HafenCity (© ELBE&FLUT) Start slideshow
For a long time in the past, the area making up today’s HafenCity was devoted to industrial and port uses. From 1862 onwards, when artificial port facilities were developed, it assumed the layout of harbor basins and docks that still characterizes it today. As a low-lying island in the northern River Elbe, HafenCity is also affected by other conditions specific to the area, so that not only new external and internal connections are crucial preconditions for urban use of the site; effective protection against flooding is also an essential.
Here the initial challenge was the east-west orientation of the Speicherstadt, the waterways and wide Willy Brandt Strasse: together they form a broad barrier between Hafen-City and the city itself. That also meant, for instance, that effective connection with the public transport system could only function well underground. Since HafenCity is also situated outside the main Hamburg dike line at a level of 4–5.5m above sea-level and thus vulnerable to flooding, special protection measures needed to be taken.
Effective flood protection an essential prerequisite
Dike construction was ruled out, since it would have had to encircle the whole 127 ha land area of the new district before realization of the first buildings. A rapid start to development would not have been possible either. Also, as well as generating considerably higher costs, the urban spatial relationship to water so characteristic of HafenCity would have been prevented, at least at ground floor level.
Instead, the new buildings and roads are built on plinths, or “Warfts”, that are formed at a height of 8–9 m above sea level, adjoining the raised streets and thus protecting against flooding. Their interiors also offer space for flood-protected underground garages. Promenades and many squares, on the other hand, remain at the area’s previous level of 4.5–5.5 m above sea level, which maintains the close relationship to water and creates high-quality, usable public spaces. All roads are built at a minimum of 7.5 m or 8.3 m above sea level, protected against floods. New bridges are built in flood-protected form, or old ones upgraded and lifted.
One exception to the rule of raising road levels is the street running between HafenCity and the historic Speicherstadt. Elevation of the whole width of Am Sandtorkai/Brooktorkai would have been extremely difficult and would have made no sense due to the proximity of the Speicherstadt. Thus only its eastern end has been raised.
To allow for the unusual and brief occurrence of a storm surge, therefore, the Kibbelstegbrücke bridges were erected, providing a new second flood-secure connection between the dike-bound city center and HafenCity: under normal conditions they function as a comfortable crossing for pedestrians and cyclists, but under flood conditions they guarantee access for fire and rescue services.
The second flood-protected traffic axis to the rest of the inner city runs via Oberbaumbrücke bridge and Brooktorkai, Shanghaiallee and Überseeallee roads. The latter is also open to private vehicles during flooding. Additional flood-secure links will be formed via Freihafenbrücke bridge, which connects with flood-protected Versmannstrasse, and perhaps also via Grossmarktbrücke.
New roads and bridges
An additional challenge is the ground itself in the new city district. HafenCity’s location on the Elbe marshes is subject to the alluvial influence of the river, which means that the upper layers of soil are made up mostly of clay and glacial sediment. As so-called cohesive layers, they are highly water absorbent, which means they cannot bear heavy weight. Sand, which is load bearing, begins further down. This is why all buildings in Hafen-City are built on piles. These are usually driven around 20 m deep into the earth, which transfers the weight to the loadbearing sand layers. In Strandkai neighborhood and southern Überseequartier a departure from pile foundations is taking place for the first time: basements are actually being excavated down to the loadbearing sand level, in some cases to 7 m below mean sea level.
For road building, preloading is used to raise the level temporarily to around 11–12 m above sea level: the weight of heaped up sand presses any water out of the cohesive layers of ground below, creating a stable foundation suitable for road building. When this process is finished, the sand preload is removed down to the future level of the road, so that piping and conduit can be laid and roads built.
Roads in HafenCity are planned in at an early stage but the realization of road surfacing, pavements, cycle lanes, tree-planting or parking bays only takes place gradually and in close coordination with construction firms. Because road surfaces would be largely destroyed during structural engineering, almost all carriageways are given a temporary surface. After completion of the surrounding buildings, the final surface is then laid and finished, together with ancillary surfaces, cycle paths/strips and tree planting.
Through the city by car
Four road bridges currently connect Hafen-City with the city center. Central northern access is via Am Sandtorkai/Brooktorkai. From here traffic fans out to the south; primarily via Shanghaiallee and Osakaallee. The northern extension continues across Kornhausbrücke bridge following on from the so-called “Domplatz axis”. The most important and easternmost access is Versmannstrasse, which is being rebuilt as a four-lane, raised avenue, in parallel with extension of the U4 subway line to Elbbrücken; part of the road runs directly above the subway tracks. The temporary traffic diversion runs over Baakenhafen bridge and alongside the Elbe to the Elbe bridges. When operations recommence, traffic can be channeled back to Versmannstrasse, and the Elbe embankment will be relandscaped as a broad green promenade with sidewalks and cycle paths.
The job of renewing and widening Zweibrückenstrasse bridge was satisfactorily completed in summer 2016. In the process, the sharp northern bend of Zweibrückenstrasse was modified and the street directly joined onto Baakenwerderstrasse. The new works have not only provided a wider thoroughfare and better paths for cyclists and pedestrians, its sustainable pump and drainage system is now much better protected against flooding.
New bridges over Baakenhafen
Two bridges connect the northern part of Baakenhafen neighborhood with the southern area. Much admired for its range of functions, the bridge has been showered with praise and prizes – including the title “Structure of the Year” from the Hamburg architects and engineers association (AIV). The 170 m-long Baakenhafen bridge, opened in August 2013, also marked another important milestone in the rapid development of eastern HafenCity. The crossing is supplemented by a central pedestrian bridge, to be finished in early summer 2017, between the northern neighborhood area and Baakenpark promontory. It will also carry all supply and waste drainage lines from southern Baakenhafen.
Environmentally friendly transport
HafenCity’s central situation and good accessibility are increasingly an invitation to leave the car behind – particularly as HafenCity's short distances and branching, unusually dense network of paths make it ideal for cycling and walking. The majority of cycle paths and footpaths are isolated from motorized traffic, running along promenades, piers and squares, often along the waterside. Cycle lanes are standard on streets with heavier traffic.
People with limited mobility or sight can move about HafenCity easily. Despite differences in height, a mass of measures make open spaces virtually barrier-free. The most important walking and driving routes are equipped with wheelchair-accessible ramps; acoustic signals can be operated at traffic lights, and the surfaces of promenades have been made with an eye to walking and rolling quality, using cut (and therefore smooth) cobblestones.
An essential requirement for sustainable development in HafenCity, with its dense mix of uses and high number of visitors, is also an efficient public transport system. The start of U4 subway services – the line was not foreseen in the original Masterplan – to Überseequartier station in December 2012, therefore, represented a major new link in the public transport chain. Since then regular services have connected HafenCity directly to Jungfernstieg and the central station. In August 2013, services to the HafenCity University station followed. Two months earlier the ground-breaking ceremony for the extension of the U4 through to the Elbe bridges took place. The last 1.3 km section runs from HafenCity University station to the new subway station at Elbbrücken. From 2018 it will link the eastern neighborhoods with their more than 3,000 homes and some 20,000 jobs.
Subway, ferries and buses
In the course of construction of the U4 subway extension, work on a new above-ground subway station at Elbbrücken, designed by the Hamburg office of Gerkan, Marg und Partner (gmp), began in April 2015. At the same time Deutsche Bahn AG is building a new Elbbrücken rapid transit (S-Bahn) station. From 2018 the station will serve eastern HafenCity as well as parts of Rothenburgsort, a suburb to the northwest, and ensure better connections to the Hamburg public transportation system. As well as the entrance building, the Elbbrücken station construction project also includes a glassed-in footbridge between the stations.
There is also a dense network of bus stops in HafenCity: the MetroBus 6 serves the Auf dem Sande stop in the Speicherstadt; the new 111 line, skirting the port and known as “Hamburg’s cheapest city tour”, initially runs from Fischereihafen, the fishing port, through HafenCity to Baakenhafen and will be extended to Elbbrücken. The first ferry pier has also been installed near the Elbphilharmonie. Two more could follow: at HafenCity University and the Elbbrücken. In addition there are various jetties for port barges, for instance in Magdeburger Hafen and in Baakenhafen harbor basins.
Planning and realization of these complex infrastructural measures – except on private land – is the responsibility of the developer, HafenCity Hamburg GmbH, owned by the City of Hamburg. Financing is covered exclusively by sales of land in the planning zone. However, finance for the new U4 subway line is an exception. It is being planned and realized by Hamburger Hochbahn AG, and financed out of budgetary funds of the Free and Hanseatic City of Hamburg as well as federal subsidies. The cost of the extension of the subway, however, will be carried by Hamburg’s special fund under public law holding “city and port” assets, while the cost of external access to HafenCity, the planned reconstruction of Deichtorplatz, as well as bridges to be built between HafenCity and other city neighborhoods, is also financed primarily out of Hamburg’s budget.