Civil Designer Showcase

Developing vision

Transforming a slice of land into a city

The accomplishment of Century City as a mixed-use development, 10 kilometres from Cape Town's central business district, demonstrates how thriving urban spaces are those that achieve the optimal balance between aesthetic, functional and commercial interests.

Earmarked for development in 1997, the 250-hectare Century City site was transformed from a waterlogged marshland in the northwest sector of Cape Town (in its first phase), to a commercially viable land parcel, which was then acquired by Rabie Property Group in June 2004.

Since inception, almost 980,000 square meters of commercial, residential, retail and lifestyle bulk has been allocated. This includes 4000 residential units and more than 580,000 square meters of office and retail bulk. This has created an integrated, multiple purpose, mixed-use precinct that successfully complies with the city's vision to promote growth along its strategic corridors and prevent sprawl on the urban edges.

Roads and Parking at Century City
Roads and Parking at Century City


It is viewed as an area that is complimentary to the CBD and other major centres - "which together provide a network of multi-nodal opportunities within the metropolitan area."

Re-imagining development

Transforming the pocket of land from its from its former condition to the high value property development it has become - encompassing a regional shopping centre, corporate offices, private residences and an intelligent city infrastructure - required vision and imagination on a grand scale during each of its successive phases of planning.

"The first developers, Monex, formalized the water bodies, created a wetland and natural conservation area as well as a stormwater system and large water retention pond. They created a local road network and transportation linkages, which made Canal Walk possible. When it opened in 2000, Canal Walk was the largest shopping centre in Africa. Today it has been eclipsed by larger competitors in Durban and Johannesburg, but it still is the third largest shopping centre in Africa."

According to Fred de Villiers, Technical Director of HHO Africa's Urban Infrastructure Division, the acquisition by Rabie then jump-started Phase Two of the development, and with it, HHO's appointment as the consulting engineers responsible for all the transportation modeling and planning as well as the full spectrum of roads and municipal services.

The Civils & Roads

HHO Africa began with the bulk earthworks to the extent of 250 000 m3 on a relatively flat site.

"The first thing we had to do was a mass earthworks exercise because the site was quite flat. So we did an optimization exercise where we optimized the cut and fill using Civil Designer.

What was great, besides the cut and fill optimization (of the software), was the cut and fill contours which helped with the planning on the project. The drawings that were then issued to the contractor were a useful tool in planning the operations."

Bulk earthworks at Century City
Bulk earthworks at Century City


HHO Africa were additionally contracted to design the internal roads and streets, a network of 11km that subdivide the precincts into development blocks and play an important role in providing public linkages between urban spaces and the various development parcels.

The configuration of the development is guided by a central open space - "the soft heart of Century City formed by the Wetland, Ratanga Island, the Grand Canal and a linear network of narrower canals that connect these spaces."

A system of radial streets intersect at strategic points to the concentric form created by Century Boulevard on the perimeter and the open space system at its core. At intermittent intersections throughout the development, traffic circles are used to control vehicular movement - and 15 of these HHO Africa designed.

"We used Civil Designer to model the traffic circles. You have to raise them so that they stand out, that is, the central island has to be higher and this is done using bitchumen and asphalt."

Public Transport

Transporting people in and out of Century City was one of the most important elements of the project, whereby development rights were granted in exchange for the provision of public transport infrastructure. A total of 16 000 people a day commute to and from the Century City complex.

 
Aerial View
Aerial View


HHO Africa used Civil Designer to build a public transport interchange in the northern part of the site (near Bosmansdam Road) for the feeder shuttle buses and parking for private vehicles. They also extended the 600mm gauge Light Rail System route and have been involved with the Integrated Rapid Transit System that in the near future will help free up the roads and ease congestion into the area.

The external roads leading to Century City are owned by the Municipality or Province and maintained according to their standards.

Water Systems

According to the Century City Urban Design Framework, the focal design feature of the development is the water system comprising the central wetland and series of canals. Water comes from a number of sources, including natural groundwater and recycled water from the Potsdam treatment works.

The series of narrow canals that make up the Internal Canal Network traverse the various precincts to form a "public amenity of great value. Apart from the obvious aesthetic benefits, the canals promote an active lifestyle where walking, running and canoeing is encouraged."

The public is granted access to these spaces with human scaled pedestrian streets terminating in local "pocket" squares at the water's edge.

HHO Africa designed 1.5km of the canals, two of which created islands for the exclusive residential estates - Waterstone Isle and Knightsbridge.

Besides creating a choice lifestyle product and waterfront addresses, the amenity value offered by the water systems provide boating opportunities with running and walking trails circumnavigating the waterways. This all forms part of the broader rationale to generate a responsive environment and 'sense of place.'

A unique system of water purification has been established to ensure that the recycled water is maintained to an acceptable quality.

As set out in the Urban Design Framework report: "This includes a combination of engineered and ecological treatment by passing water through filtration processes in the wetland. The wetland does therefore not only function as a visual and environmental asset, but is vital to the healthy operation of the water systems at Century City."

A Canal
A Canal at Century City


Whilst the wetland and canals are designed to accommodate normal and surplus stormwater during major floods, it was important to minimize pollution into these schemes and as such "low flow" and "high flow" systems were created.

"We did a study using Civil Designer's Stormwater Module where we actually evaluated the bulk stormwater system. Because we inherited the project, we had to prove to ourselves that the system worked and would be able to handle the increased runoff from future developments. We could not afford an increased risk of flooding and needed a reliable model to confirm the operation of the canal and wetland system," says de Villiers.

"All the stormwater gets polished in the wetland - you can see there are 3 or 4 cells in the wetland so that all the stormwater that comes in gets filtered through these cells and that takes out pollutants. There is a water attenuation pond that serves as a buffer, and from there a relatively small pipe directs the flow out to sea. The run off here is about 1 m³ per second."

Conclusion

When asked about the constraints or particular challenges faced by HHO Africa on the project thus far, de Villiers concedes that the high water table meant restrictions on the bulk earthworks cut operations.

Then there were the normal challenges of developing major infrastructure in the midst of current development. Strict enforcement guidelines are further set out in the Construction Environmental Management Programme that looks at elements like litter and fencing off of the construction sites.

The entire development is underscored by stringent criteria for the functional, structural and environmental aspects of the built environment as contained in the Urban Design Framework.

For de Villiers and the team at HHO Africa, it has been a privilege to be part of the Century City Development.

"Rabie has been a good client of ours for many years. They are visionary and make things happen. Their strength is also anticipating market demand and creating a product that is desirable.

The way they package this through signature touches, the level of detailing in the roads and landscaping - all adds up to well built solutions."


 
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