Items filtered by date: October 2015

Chapman’s Peak is named after John Chapman, the Captain’s mate of an English ship, the Consent. The peak which looms overhead was not named after a governor or brave mountaineer, but a lowly ship's pilot. In 1607 the skipper of the British ship Contest found his vessel becalmed in what is now Hout Bay and sent his pilot, John Chapman, to row ashore in the hope of finding provisions. The pilot later recorded the bay as Chapman's Chaunce (chance) and the name stuck, becoming official on all East India charts.

In the early 1920’s Sir Nicolas Fredrick de Waal, first administrator of the Cape Province, ordered the construction of a high-level road linking Cape Town with the Southern Suburbs. The roadway (De Waal Drive) was extremely well received. Enthused with this success he called for another road linking Hout Bay to Noordhoek. Two possible routes were under consideration in 1910. The route over the low nek between the Chapman’s and Noordhoek Peaks was second to the more spectacular route along the vertical sea cliffs.

In 1914 preliminary surveys on the road got under way. Surveying the route was a scary business. The cliffs and ravines were steep, rotten and unstable, and at times the surveying party was on all fours as they investigated the perpendicular terrain. The route over the nek appeared to be no better; and the project appeared to be expensive and a ‘mission impossible’. De Waal however, would not take no for an answer and eventually he ordered the ‘go ahead’ for along the cliffs which appeared, at the time to be the better option.

The road was cleverly planned with the road surface based on the solid and conveniently located on the 540 million year old light grey granite of the Cape Granite Suite on an erosional contact surface (nonconformity) overlain by sandstone and mudstone of the 485 to 455 million years old lower Table Mountain Group. The many roadside cuttings were carved out of these more workable Table Mountain Group rocks.

In 1915, with the use of convict labour supplied by the newly formed Union Government, construction began from the Hout Bay end, and in the following year work began from Noordhoek. The first portion of the road to the Lookout was opened in 1919.

This spectacular roadway took seven years to complete, at a cost of ₤20 000. The Hout Bay - NoordHoek Road ‘hewn out of the stone face of Sheer Mountain’ was opened to traffic on Saturday 6 May 1922 by the Governor of the Union of South Africa, His Royal Highness Prince Arthur of Connaught.

In 1962 a section of the road was widened, and in 1977 a portion of road was washed away, and subsequently the road was closed on 14 May, after a large section was washed away and the damaged section was replaced by a bridge at a cost of R150 000.

Road Closure in 2000

In 1994, Noel Graham was injured and partly paralysed in a landslide incident on Chapman’s Peak Drive, which resulted in a court case against the Cape Metropolitan Council who was the road management agent at the time of the incident. In February 1999 a High Court judgement was given against CMC for negligence in management of the road. The matter was appealed by the CMC but the Supreme Court dismissed the appeal in November 2000, thus reaffirming the Cape High Court’s decision, and CMC was ordered to pay all claims and costs.

Amidst increasing concern for public safety and legal liability, the South Peninsula Municipality (SPM) – the new road management agent appointed in 1997; established a sub-committee of officials from the local, metropolitan and provincial authorities to guide the management of Chapman’s Peak Drive, who instigated high visibility rockfall warning signs to be erected on Chapman’s Peak Drive during 1999. The sub-committee also adopted a specific Chapman’s Peak Drive closure policy which inter alia stipulated that the road had to be closed to traffic in rainy weather (very light drizzle excluded) and remain closed for a number of hours after cessation of any rainfall and until deemed safe by SPM’s road management staff. This closure policy/procedure was implemented by SPM’s road management staff with lockable booms put in place to prevent unauthorised entry.

On 29 December 1999 however, a falling rock caused the unfortunate death of a Noordhoek resident. In early January 2000, Ms Lara Callige was killed, and a passenger in the same car seriously injured in a rockfall incident on Chapman’s Peak Drive in good weather conditions when the rockfall risk on the road was not considered to be high. This was of serious concern to the local and provincial authorities alike and emergency meetings to discuss closure of Chapman’s Peak Drive were held between the relevant political bodies. Before a decision could be taken on the matter, and still in January 2000, the worst mountain fires in many decades raged in the Cape Peninsula, including in the mountains above Chapman’s Peak Drive, causing numerous rockfalls onto the road and effectively rendering the road impassable.

As a result of these incidents Chapman’s Peak Drive was officially closed to traffic indefinitely by the Provincial Minister of Transport in January 2000.

Development 2000 - 2003

Based on the recommendations of geotechnical specialists, the Provincial Administration’s Transport Branch made available funding for “rockbarring” (a term used for removing loose or dangerous rocks) of the mountain slopes above the road to make them safer. Contracts for this work were awarded in March 2000 by the SPM.

It soon became apparent that the rockbarring process deemed would take substantially longer than originally anticipated and cost commensurately more. The work was thus stopped in May 2000 and an integrated environmental management process (IEM) was put in place with the goal of producing an agreed management plan for Chapman’s Peak Drive by mid-2001. The IEM process brief required management to include:

1. the improvements deemed necessary to make the road safe for users,
2. a strategy for managing/operating the road,
3. recommendations on funding sources for the capital improvements as well as the continuing operational needs. 

At the end of April 2001 the IEM process had included:

1. A review of the initial “rockbarring” work which concluded that some rockbarring may be necessary in the final upgrading process, but the “clean sweep” approach could not be condoned and the selective rockbarring also would have to be accompanied by various engineered rockfall protective measures in order to make the road safe for users.
2. A comprehensive stakeholder workshop in September 2000 which identified and agreed various improvements and protective measures which needed to be implemented on Chapman’s Peak Drive with the overriding and urgent requirement to re-open the road to traffic as soon as possible being supported by all participants.
3. A detailed site survey of the road itself and mountainside above and below the road to facilitate a concept design proposal (areas covered by rock and the time had to be omitted).
4. Completion of various concept design proposals incorporating some or all of the following elements: rockbarring, catch fences, rock gallery protection, concrete roof protection, existing structure repair, road surface and layerwork repair, slope stabilisation work above and below the road, etc.
5. Public meetings were held in late November 2000 to present the current status of the project to the general public in the Hout Bay and Noordhoek Valley areas and obtain relevant feedback from interested and affected parties, and further meetings in March 2001 presented the progress on the project.

The IEM process was guided by a project management team consisting of officials from the Provincial Administration, Western Cape, and officials from the City of Cape Town’s South Peninsula and CMC administrations.

Public Private Partnership (PPP)

The legal road authority for Chapman’s Peak Drive being the Provincial Administration Western Cape (PAWC) realised early on in 2000 that financial limitations would be the single biggest stumbling block to the safe re-opening of Chapman’s Peak Drive to traffic. To solve these financial problems the plan was to implement a public private partnership and proclaim the route a Toll Road under the Western Cape Provincial Toll Road Act. The feasibility study concluded that the majority of the costs attached to the Chapman’s Peak Drive reopening and operation could be obtained through tolling the road, and that a public private partnership with a concessionaire demonstrated value for money in terms of the risks transferred to the private sector.

The Chapman’s Peak Engineering Group Joint Venture was awarded the tender after being shortlisted and the project was overseen by Entilini concessions – the special-purpose company established by the consortium of Concor Holdings, Haw & Inglis and Marib Holdings.

The Joint Venture included Vela VKE Consulting Engineers, Meli & Du Plessis Geotechnical Engineers, Stewart Scott International, Zietsman Lloyd Hemsted and assisted by Megan Anderson Landscape Architect (environmentalist); OvP& Assosciates (landscape architect); Dr Ross Party-Davies (geotechnical specialist) and Prof Rolf Kratz (structural design specialist).

Due to its sensitive location within the Table Mountain National Park, an integrated environmental approach to the rehabilitation and upgrading of Chapman's Peak Drive was required. See details on the engineering page of work that was undertaken to ensure that rock fall protection measures were put in place along with an advanced traffic management system.

2003 - Present

After intensive design and reconstruction Chapman’s Peak Drive was re-opened to traffic as a toll road on 20 December 2003. The opening was a welcome return for the drive as an “international tourist destination” complementing other tourist destinations in the Western Cape. Local businesses also welcomed the re-opening.

The new rock fall measures were however put to the test, and during July and August of 2004, three rainfall incidents occurred of extremely high intensity. A total of 396mm was recorded in the 2 months, compared to the mean annual precipitation for the area of 740mm! Shortly thereafter several debris slides and rockfall incidents occurred, resulting in damage to the catch fences and Chapman’s Peak Drive was closed for 55 days to clear the debris and replace the 4 catch fences.

The much loved road was back in the news when Chapman’s Peak Drive was once again declared unsafe for road users in June 2008 and the drive was closed for major upgrades and repairs. The construction work took over a year and was eventually re-opened on the 9th October 2009. Chapman’s Peak Drive has remained open since then, albeit with temporary closures for routine maintenance and during dangerous weather conditions.

The route took 7 years to complete and was opened in 1922. See more on the history of Chapman’s Peak Drive.

In 1962 the road was widened and in 1977 a portion of the road was washed away resulting in a bridge to replace the damaged section.

Despite its spectacular views and extraordinary beauty, the drive is not without danger, as rock falls and mudslides have always been a hazard for motorists - particular during storms in winter. Four deaths and several serious injuries resulted from rock fall incidents between 1998 and its closure as a public road in January 2000 after the last fatal occurrence, until suitable rock fall protection measures had been implemented.

In order to re-open the road to the public, the hazard from and debris landing on the road had to be substantially reduced and the associated risk and liability of injury or death to road users minimized. At the same time, the touristic, historical, aesthetic, environment and traffic implications of road widening and other substantial construction works had to be considered. All of these had to be carried out in a very short time and within a limited budget. This was the task that faced Entilini Concessions in 2002 when it was awarded a 30 year concessions for the rehabilitation and operation of Chapman’s Peak Drive as a toll road.

The rock fall protection measures implemented at Chapman’s Peak Drive were selected on the basis of what is considered to be best international practice and consists of a half tunnel, catch fences, slope stabilisation and canopy structures. In 2004, Chapman’s Peak Drive received an excellence award for rock fall protection.

The Project Engineering Solutions

Rock Fall Protection Measures: The scale of the design and construction of the Works was formidable, with many of the activities required being ‘first-offs’ in South Africa. The design of rockfall protection measures involved sophisticated three-dimensional computer modeling of the topography assessment of mountain and location of boulders on the slopes and cliffs above the road to predict the associated rockfall patterns. This modelling predicted, on a statistical basis, the location, trajectory, frequency, bounce height and energy of falling rocks along route. These predictions formed the basis for determining the optimum size and shape positions of the rockfall protection structures and for their design.

Working conditions were challenging and up to 11 different mobile cranes were deployed, as the road was too narrow to constantly move the cranes up and down. Helicopters were also used to lift drilling and grouting equipment into position at heights above 65 m, while abseilers completed the work in those inaccessible locations.

Terrain Modelling: The engineers, in association with Swiss specialists utilised a digital terrain model to generate three-dimensional simulations of rockfalls. This was supplemented by the interpretation of high-resolution aerial photographs to determine the distribution of relative frequencies, bounce heights and energies of simulated rocks of various sizes.

Half Tunnel: This is the first time that half tunnelling has been used in South Africa and entails cutting into the mountain at road level, then moving the road in under the protection of the resulting overhang. The 155m half tunnel was built at the base of Chapman’s Peak and the overhanging rock-mass is supported by 95t rock anchors. The soffit and side walls are supported by 150mm thick steel reinforced shotcrete lining.

Rock Shelters: In other places the solution to rock fall protection measures was to build a concrete canopy, similar to those at Lake Garda, Italy. These measures ensure that any rocks that do fall off the mountain will, at worst, land close to the old rock-faced guard wall, while traffic will travel safely under the canopy.

At two locations where the sandstone cliffs extend to more than 400m above the road, concrete impact protection canopies were constructed. These structures arch over the road and protect it by intercepting rock fall and debris or deflecting the material over the road and into the sea below.

A 40m long curved cantilever canopy, arching over both lanes was built on a tight bend at the confluence of three gullies. It is tied back into the cliff face at each end by 100t rock anchors and supported in the middle by 11 large pre-stressed counterfort ribs, as the fault resulted in stability concerns due to hard granite on the northside and soft sandstone on the southside.

A portal canopy coincides with the highest predicted rockfall energies and the structure is free of the cliff face. It is supported from behind by tapered columns with a row of circular sloping columns to support the front edge.

Catch Fences: A new feature is the catch fences, a sophisticated Swiss design not used in South Africa before. They consist of interlocking rings of high tensile wire designed to trap rocks as they fall, and are anchored into the rock with steel wire ropes. There are 1,6km of catch fences in different sections that are monitored and fallen rocks removed. These fences have capacities ranging from 500 to 3500kj and vary in height from 4-6metres. They are positioned at various locations and elevations above the road to suit the local topography and rockfall trajectories.

Advanced Traffic Management Systems (ATMS)

CCTV cameras, variable message signs, radar traffic detectors and a weather station linked via Fibre-optic cables to operator consoles all enable the concessionaire in monitoring risk and ensuring ongoing adequate maintenance.

According to the Chapman’s Peak Engineering Group the rockfall protection measures have reduced the risk of rockfalls reaching the road by 90%. However in cases of severe weather conditions the risk will be further reduced by closing the road temporarily.

In terms of adhering to environmental criteria, an independent environmental scoping report was completed prior to the design and construction work commencing. An environmental monitoring committee was appointed and an independent environmentalist constantly monitored the work. An environmental consultant supervised the removal of alien vegetation and harvested indigenous plant seeds. These were propagated in a nursery and planted in disturbed areas.

A landscape architect ensured that the structures conformed to the ‘sense of place’. This included ensuring that rock-packed retaining walls were reinforced with pigmented shotcrete and rocks packed into pigmented gabion baskets.

According to the Chapman’s Peak Engineering Group all targets for black economic empowerment and the development of local small businesses were achieved. A portion of the project’s equity was invested in a community trust to benefit local disadvantaged communities. During construction 40 members of the local community were trained as abseilers, while others were trained in the art of constructing stonewalling.

A Triumph for South African Engineering

The re-opening of Chapman’s Peak Drive in 2003 was heralded as a great success, enabling tourists and locals to once again experience the exquisite beauty and engineering magnificence of the drive. The coupling of 21st-century cutting-edge construction processes with the courage and determination of the early 1920's when the original drive was build, has resulted in this project showcasing the outstanding talents of South African engineering.

Awards

• Winner of the SAACE National Award for Engineering Excellence (2004)
• Winner of the SAFCEC National President’s Award (2004)
• Winner of the Bentley Systems prestigious international award (civil Design) for 3D and 2D rockfall hazard analysis and design using the Microstation suite of geospatial software packages (2004)
• Runner-up in SAICE’s National Award for Excellence in Civil Engineering (2004)