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 – one of which is the Table Bay Boulevard which has been completed.
The completed project
Phases
Phase 1
- Directional ramps connecting the M5 with the N1 (north and south-bound) \
- An extra traffic lane on the N1 in-bound
- Widening the N1 out-bound through Koeberg Interchange to three lane
- Two extra traffic lanes on the N1 out-bound after Koeberg Interchange to Sable Road '
- Relocating existing services and modifying existing structures, and minor realignments
- Rehabilitation of the existing interchange
- Widening of M5 bridge from Berkley Road
- Shifting the Black River Canal by 15 m
Phase 2
Implementing the N1 BRT Busway Scheme, under Koeberg Interchange, and then utilizing the area of the disused Paardeneiland railway line
Widening of M5 from Berkley Road to N2 by adding an additional lane in both directions
Phase 3
Widening the in-bound carriageway of the N1 through the Koeberg Interchange from two to three lanes
Scope of works
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Structures: |
Viaduct A & B
- Ramp A - 640 m long and 10.7 m wide
- Ramp B - 690 m long and 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
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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 (each beam of different length)
- Strengthening of existing bridge deck
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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
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Rehabilitation
Rehabilitation of ramps in Koeberg interchange
- Approaches to directional ramps (520 m)
- Selected sections of ramps
Shifting Black River Canal:
- Relocating canal by 15 m using local labour
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Ancillary works
- Pre-cast panels - precast yard
- 3400 No Panels
- Pre-cast balastrades 4 km
- Services relocation-critical to the contract
- 11 km of 11 kv and 20 km of 66 & 132 kv cables
- Street lighting
- Landscaping
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Road closures?
No lane closures are permitted during working hours. The placing of beams however requires closures at night. Alternative routes are signposted and closures will be communicated via KFM and Cape Talk.
Budget and timing
The Koeberg Interchange project is expected to cost R696 million. The ramp from N1 to M5 has been completed and the remaining ramp is expected to be completed in May 2011, about eight months ahead of programme.
Contacts
The consulting engineers: HHO Africa
Resident engineer: Leon Bester
Cell: 082 440 5745
E-mail: Leon@HHO.co.za
Construction progress
(Click on image to view larger image)
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(All images taken by Bruce Sutherland, City of Cape Town)