Chapman’s Peak Drive #8: Engineering Solutions pt2
This is the last in a series of 8 caches (incorporating 2 existing and 6 new ones) along the northern half of this 9 km long, world famous, spectacular and award-winning cliff-edge mountain pass.
The cache, a small camo-taped flip-topped tablet pot is hidden beside the road a short walk down from the nearest shady parking/picnic area.
See GC9KPCD CPD #3 for toll tips.
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 3,500kj and vary in height from 4-6m. 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 to monitor risk and ensure ongoing adequate maintenance.
According to expert engineers 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. See here for a detailed 2005 paper on the protective reconstruction of the road
Part of the project’s funds were invested in a community trust to benefit local disadvantaged communities. construction 40 members of the local community were trained as abseilers, and others were trained in the art of constructing stonewalling.
Reopening: when this finally happened in 2003, it was praised 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 1920s when the original drive was built, has resulted in this project showcasing the outstanding talents of South African engineering which has been recognised with several awards.
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 CPD was closed for 55 days to clear the debris and replace the 4 catch fences.
In June 2008, it was again declared unsafe for road users and closed for major upgrades and repairs. The construction work took over a year and it was eventually re-opened on the 9th October 2009. It has remained open since then, albeit with temporary closures for routine maintenance and during dangerous weather conditions.
See here for another great drone video of CPD and here for one of the many YT videos available of a (real-time) drive along CPD.
Some Additional CPD Facts . . .
Apart from normal daily use by vehicles, cyclists and pedestrians, the CPD is also used in several special races including:
The Chapman’s Peak Half Marathon: this race aka the Chapman's Peak Solo Challenge has 3 routes (21km/10km/5km) run single file along CPD from Hout Bay to Noordhoek/Viewpoint/Toll Plaza and back. Best respective times as of December 2020 are 1:37:08/37:53/41:08 (for 50-59 yo). See here for a video of the 2019 race.
Two Oceans Ultra Marathon : known globally as the world’s most beautiful (and windy!) marathon, this is the Western Cape’s most prestigious road race (56km) and takes place annually on Easter Saturday. There is also an associated half marathon. The route starts and finishes in Newlands/UCT campus and goes via Muizenberg, Fish Hoek, Noordhoek, Chappies, Hout Bay, and Constantia Nek. Up to 11,000 athletes compete and the best time/course record set in the last ultra race - run on 20/4/19 - was 3:08:39. The best time for the half-marathon is 1:03:15 set in 2017. See here for a short 2018 video going over the route and its challenges.
Cape Town Cycle Tour: this road race, with up to 35,000 riders taking part, is the largest timed cycle race in the world. It started in 1978 and takes place annually – usually on the 2nd Sunday of March - around Cape Town. It includes the highest section on the route (at 169m) over CPD – unless weather conditions are too bad or there area other hazards (ie. too windy over CPD, fire in Hout Bay) when an alternative route over Ou Kaapseweg and along Blue Route is used. In 2017 the race was cancelled on the day due to winds up to 100kph on CPD.
Course records for conventional bicycles for the normal 109 km course over CPD are: Men: 02:27:29 by Robbie Hunter (2008) Women: 02:44:04 by Renee Scott (1991). See here for a 2015 video highlighting the race and route.
