by Harry Valentine
There was a time prior to the early to mid 20th century when a “penny ferry” operated in the older section of the Cape Town docks, ferrying passengers across a channel that today forms part of the Victoria and Alfred Waterfront area. Prior to the introduction of the MyCiTi bus initiative between Cape Town centre and the Table View area, there had been some discussion about a possible trans-bay ferry operating between terminals at Table View and the V&A waterfront. Overseas, short-distance maritime passenger vessels provide municipal transportation, complementing the services of high-capacity rail and road passenger vehicles.
An extensive network of ferries carry thousands of passengers who commute between home and work during the AM and PM rush hours at New York City and Hong Kong. The variety of ferry vessels includes the traditional mono-hull design, twin-hull catamaran, hydrofoil and even hovercraft designs. Some hybrid ferry designs combine the features of catamaran and hydrofoil, or catamaran and hovercraft. While the traditional design operates at comparatively low-speed, the fact that they operate non-stop between 2-main terminals over shorter distances that railway lines of bus routes, allows them to achieve competitive travel durations.
A maritime ferry can carry the capacity of a fleet of buses or even a fleet of commuter trains, moving massive numbers of commuters at very competitive cost (monetary unit per person-kilometre) against bus and commuter rail transit, often consuming less energy per passenger-kilometre than either bus or railway services, especially at coastal locations where passenger loadings would otherwise overcrowd commuter trains. The larger ferry vessels that operate at New York City and Hong Kong can carry the passenger loading of several Cape Metrorail trains.
Cape Metrorail trains experience overcrowding on weekdays, between 7:00AM and 8:00AM. A large ferry vessel may carry the capacity of several trains and incur lower right-of-way costs and lower energy-consumption-per-passenger on the trans-bay service, than a Metrorail train. A small fast-ferry carrying the equivalent passenger load as taxi-van may operate fast (time-duration-competitive) service directly across Table Bay, at comparable cost. A large (slower and high-capacity) ferry and also a small (fast – speed boat) ferry may both offer cost-competitive and tariff-competitive service across Table Bay.
A transit bus may achieve an average speed or 10-km/hr in traffic, perhaps 6 to 8-km/hr in rush hour traffic and a balance speed of up to 30-km/hr in multi-stop service along a dedicated right-of-way such as a busway. When sections of the busway intersects with city streets and mixes with other traffic, average speed may drop to 20 to 25-km/hr. At Cape Town, the busway between Table View and City Centre follows the horseshoe curvature of Table Bay, a longer distance than the straight line across Table Bay between V&A and Table View.
Ferryboats will sail a shorter distance directly across Table Bay, between terminals at V&A waterfront and Milnerton/Table View. A traditional mono-hull ferry may achieve a top speed of 40-km/hr on Table Bay and a balance speed of 25-km/hr. Modern s.w.a.t.h. (Small-water-area-twin-hull) catamaran vessels incur relative low water drag due to their shallow draught. They can achieve a maximum speed of 75-km/hr and a possible balance speed of 50-km/hr across Table Bay. A catamaran ferry can sail both on the ocean waves of Table Bay and also into the mouth of and partway upstream of Diep River at Milnerton.
Depending on vessel dimensions, any of several designs of trans-bay ferry vessel may sail through the V&A docks and into the Cape Town canal where a terminal may be located within walking distance of either Dock Road or Helen Suzman Drive. A floating dock may serve as a terminal at V&A, also at several locations along a modified Diep River, near MyCiTi bus stations. Pre-arranged taxi-vans may also interline with the trans-bay ferry during AM and PM rush hours at both ends of the voyage, to carry riders to/from home and to/from places of employment.
Ferry Navigation along Diep River:
There would be scope to install semi-automated water flow-rate control technology near the mouth of Diep River to extend ferry navigation further upstream. Inflatable bags placed across the riverbed in pairs, at a distance from each may be pumped with water to restrict river flow. During periods of high water, the bags remain deflated. As river levels decline during summer, water may be pumped into the bags to restrict water flow rate to assure sufficient navigation depth upstream of the pumped locks. The bags would deflate with water being pumped upstream, to allow ferry vessels to pass over.
During drought conditions, there may be need to pump seawater partly up Diep River to maintain ferry navigation. To save water, there may be scope to borrow a precedent from the European barge canal system, the side reservoir that reduces water usage by over 65% to transit a pair of barges sailing in opposite directions. There may be scope to access electric power from Metrorail or from storage batteries to operate the water pumps. During summer drought, there may even be scope to pump seawater into the Cape Town canal, to assure ferry operations.
New and evolving developments in technology can allow for electric power to assist in accelerating ferry technology so as to reduce trans-bay fuel usage. Energy stored in flywheels or ultra-capacitors could accelerate each ferry as it begins its trip Table Bay. Flywheels and ultra-capacitors would recharge during layovers at terminals. Flywheel power may propel some ferries across Table Bay. During layover involving other ferries, electrical pumps may pump seawater to high pressure in seawater-over-compressed-air storage systems that would accelerate the ferry at the beginning of each crossing, with a water turbine driving the propeller(s).
Alternative power may even involve steam power and thermal batteries that blend in as the acceleration from pumped/stored energy is depleted. Thermal batteries containing 80% lithium hydroxide and 20% lithium fluoride may melt at 465-C with a heat of fusion of 1,000-KJ/Kg and may hold enough energy to operate 3-hrs duration during the peak periods. Thermal-storage ferries would recharge thermal batteries at Koeberg thermal power station, courtesy of a possible agreement with Eskom. Other possible propulsion systems may involve a submerged cable activated by land-based electric motors that pulls the ferry across Table Bay.
A ferry service sailing across Table Bay could complement the MyCiTi busway system during rush hours, by operating direct express trips between terminals located at Milnerton/Table View and V&A Waterfront. Passengers who travel between V&A area and Milnerton/Table View may choose either the fast, direct ferry or the slower, multi-stop and possibly crowded bus. The ferry would only operate during rush hours and carry express trans-bay riders while the MyCiTi buses would serve riders who board/alight at the intermediate stations. Buses would provide off-peak services.
The combination of trans-bay ferry and busway service may be a cost-competitive and viable alternative to commuter train service. As future population in the Milnerton/Table View area increases, ferry/busway patronage would also increases. A larger ferry technology or more frequent trans-bay ferry departures could carry the increased passenger loadings that could exceed to capacity aboard the commuter trains. In the distant future, the combination of larger ferry vessels and larger buses could carry increased future passenger loadings that result from an expanded population at Milnerton and Table View.
Cape Town previously operated Leyland Victory Mark 1 double decker buses built to a height of 4.56-m with a lower deck floor comparable to that of MyCiTi buses. Hong Kong added sway bars to the front and rear suspensions of these double decker buses to assure stability. There would be scope for Volvo (model B10M or D10M chassis) Scania or MAN (model Lion chassis) to offer a bus chassis capable of carrying a double decker body, for use along the busway.
The relatively straight route of the busway assures safe operation of excess-height double decker buses, also of extended length and road-train versions of these vehicle options. Courtesy of negotiation with the Minister of Transport and his officials, there may be future opportunity to introduce an extended-length straight-chassis double decker bus to busway service, with an option of an articulated (road train) version capable of carrying extreme passenger loadings.
As the combined population of the Blouberg and surrounding area grows, the combination of larger, more frequent buses on the busway and rush hour trans-bay ferry services could carry an increased passenger load. There will be a need to co-ordinate the travel times of a possible trans-bay ferry service with operation of ships arriving at and sailing from the Port of Cape Town. Such co-ordination would assure smooth and safe operation of the ferries and vessels of international origins that call at Cape Town.