Some of the worst traffic congestion in Cape Town is experienced at the Koeberg Interchange, where the N1 and M5 highways intersect.

The intersection was designed and built long before the drastic increase in traffic experienced today, and also before the many business, shopping and residential developments such as Canal Walk in the area added to the already busy traffic flow.

A study on the N1 Corridor identified the need for several infrastructural improvements, including this interchange.

The City of Cape Town owns the Table Bay Boulevard section of the N1 between the city centre and Salt River, while the N1 from Salt River to the R300 (including the Koeberg Interchange) falls under the Provincial Government of the Western Cape.

Forces were joined and the implementation of the infrastructural improvements and additions was split into phases. Due to the size and complexity of the project, it has been split into more than one contract.

The completed project

Phase 1

• Directional ramps connecting the M5 with the N1
• An extra traffic lane on the N1 south-bound
• Widening the N1 north-bound through Koeberg Interchange to three lane
• Two extra traffic lanes on the N1 north-bound after Koeberg Interchange
• An extra lane on Table Bay Boulevard north-bound
• Relocating existing services and modifying existing structures, and minor realignments
• Rehabilitation of both carriageways

Phase 2

Implementing the N1 BRT Busway Scheme, which will use the area of the disused Paardeneiland railway line

Phase 3

• Widening the south-bound carriageway of the N1 through the Koeberg Interchange from two to three lanes
• Building an extra traffic lane on the south-bound carriageway of Table Bay Boulevard between Koeberg Interchange and Marine Drive Interchange
• Building of a walkway deck and pedestrian paths
• Widening of the bridge carrying Table Bay Boulevard over the disused Paardeneiland railway line

Scope of works

Structures:
Viaduct A & B Ramp A - 640 m long & 10.7 m wide Ramp B - 690 m long & 10.7 m wide Precast U-type post-tensioned beams - 135 no 27 spans mostly 35m long - 70t per beam Two single span in-situ sections in-situ sections over railway tracks - 63 m long Two 3-span continuous sections - 137 m long Total deck area - 14 231 m²
Widening From Berkley road interchange to Koeberg interchange Foundation - spread footings or/and piles (500 Ø) Columns to match existing Length 375 m long - 130 No Post-tensioned T-beams
New Roadworks Additional lanes on N1 and M5 carriageways N1 Outbound lane - 4 500 m (2 additional lanes) N1 Inbound lane - 2 800 (1 additional lane) M5 Both carriageways - 360 m
Rehabilitation Rehabilitation of ramps in Koeberg interchange Approaches to directional ramps (520 m) Selected sections of ramps
Ancillary works Reinforced earth walls Pre-cast panels - precast yard 3400 No Panels Services relocation-critical to the contract Street lighting Landscaping

Road closures?

While there will be some road disruptions and fewer lanes, the contractors and city officials will make every attempt to ensure that traffic flow will not be adversely affected, especially during peak hours.

Budget and timing

The Koeberg Interchange project is expected to cost R610-million, while the Table Bay Boulevard rehabilitation project will cost R120-million.

Construction progress
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