Civil Designer Showcase

M5/Koeberg Interchange - Transport alternatives beyond 2010


Earmarked by the Western Cape Provincial government, and designed by HHO Africa Infrastructure Engineers, the Koeberg Interchange forms part of the national transport planning grid which links provinces and municipalities together in key projects throughout the country.

Transport Corridors
Strategic transport corridors have been identified as critical zones for investment as part of a countrywide Multimodal Transport Strategy targeting public transport and road infrastructure, rail upgrades, internodal facilities, the Bus Rapid Transit (BRT) system, inner city mobility and airport city links.

Cape Town's Koeberg Interchange is one such corridor, serving as a primary freight artery and mobility route between the Cape Town and Bellville CBD.

The overview for a project such as Koeberg Interchange, with a total capital value of R730 million, extends beyond the question of how to improve mobility between the M5 and N1 South and Northbound. It is part of the broader transformation to formalize public transport services and to remodel South Africa's skewed transport infrastructure, much of which has not been significantly developed in decades.

Infrastructure Investment
Without the infrastructure spend designed to alleviate congestion and the resulting deteriorating air quality, a city such as Cape Town would be under mounting pressure to manage the increased vehicle load, which currently stands at more than 1 million registered motor cars.

Koeberg Interchange alone has about 200 000 vehicles passing through its network every day. An economic analysis of the upgrade revealed that significant savings in travel time would be achieved through its development, translating to direct benefits for the province.

Design and Software
The fast tracking of Phase 1 to meet delivery targets for 2010 has meant that a lot of the design process has run parallel with construction. For the preliminary and detailed designs, Graeme Warrin, Associate of HHO, used a South African developed software package developed by Knowledge Base for application across their projects.

Koeberg Interchange
Road over rail bridge under construction

Says Graeme, "I used Civil Designer software to come up with the vertical alignment and to produce a design that was geometrically sound. To do this I had to make sure that all the geometric parameters were satisfied. For an 80km design speed I had to get all the constraints using maximum grades and the K values."

The World Cup has been the catalyst to leverage partnerships and resources to advance the timetable of the Province's Strategic Infrastructure plan. This accelerated delivery has meant that severely congested nodes such as the Koeberg Interchange will benefit beyond 2010, toward the longer-term goals of a more efficient urban transport model.

Global, Greener Models
The move towards a more sustainable transport solution is part of an international trend to greener, smarter and traffic-free ways of commuting where alternative modes to the single occupancy vehicle are being sought.

Drawing from examples of successful implementation in South American cities such as Curitiba, Bogota and Sao Paulo, Cape Town's IRT infrastructure will comprise upgraded Metrorail services and the BRT bus-only lanes with stations at strategic intervals, working on a system of trunk and feeder routes. Smart card technology will ensure that commuters have one mode of payment for their entire journey, be it in a train, bus or taxi.

The advantage of the BRT lies not only in the comfort and convenience passed on to passengers, but also on its value versus alternative transport modes, an average of 4 to 20 times cheaper than a tram or light rapid transit system and 10 to 100 times more cost effective than rail.
Koeberg Interchange
Koeberg Interchange | HHO Africa

The scope of the project, divided into a two-part process, entails the provision of additional traffic lanes along both N1 carriageways between Marine Drive and Sable Road Interchange and the construction of two new, third level ramps. Ramp A, which will carry traffic directly from the N1 to the M5 and Ramp B, will ferry traffic from the M5 to the N1.

It includes the widening of the M5 Viaduct with two single-span sections over the railway tracks and the realignment of the Salt River Canal as well as provision for future BRT infrastructure development on the N1.

HHO Africa
The engineering solutions for the project required an understanding of bringing a concept to reality and one that reflected the aesthetics of a gateway icon. The preliminary and detailed designs produced by HHO also had to account for the accelerated delivery of Phase 1 by May 2010.

Says Brian Dreyer, Director at HHO, "2010 drove the project and focused on getting substantial portions of it completed with just-in-time design information as we constructed."

Turning the questions of how to meet a set of complex criteria into a final product was the result of many project management team meeting discussions and collective knowledge from all the role players.

The PMT process involved a cycle of concept development, presentations to the client, and the review, revision and acceptance of the way forward. A critical issue was the achievability and practicality of designs to minimize interference with critical traffic flow and maximise off-site construction.

According to Brian, "We had to ask ourselves how we were going to build the superstructures with the current traffic volumes and decided to use pre-casting in order to minimise the disruption to road users."

Group Five and Power Construction, the contractors who together form the consortium known as Paarden Eiland Joint Venture, developed a trailer system to transport the 70ton U-beams from the casting yard to site. The beams are lifted over the canal using an 800-ton crane with a 78 boom and placed on the completed piers.

HHO's involvement in the BRT comprises the project management, design and construction aspects of the stations, stops and depots for the route covering the full length of Blaauwberg Road, up to Potsdam Road just north of Du Noon as well as the sections through Culemborg under the N1 freeway, through Paarden Eiland (along the Old Rail Spur) and along the R27.

Beyond 2010
Beyond the immediate needs of 2010, the government is also currently putting in place a major policy initiative on public transport, the National Transport Master Plan (NATMAP), which it plans implementing in five-year cycles, from now through to 2050.

According to the Minister of Transport, Sibusiso Ndebele, the transport modes must be integrated to deal with the challenge of the last mile. This refers to the uneven distribution of public transport that leaves many commuters stranded at stations and taxi ranks after peak hours.

Construction Participation Goals
Koeberg Interchange has been a pilot project in many respects and also reflects a new approach by the Department of Transport and Public Works towards an Affirmative Procurement Policy, which targets local labour and more aggressive procurement of raw materials from suppliers with BEE status 1 to 4.

The objectives for the targets are to pass on benefits to local subcontractors to the value of R100 million, of which 10% will be allocated to businesses owned by women. Additionally 500 hourly-paid construction workers would hail from the surrounding areas, and receive life skills and technical instruction in line with the Construction, Education and Training Authority (CETA) programmes.

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