bulkhead plates
a) isometric view of typical tremied
concrete joint
hydrostatic pressure
bulkheads
I
gasketed joint
relief cock
trapped water
b) long section showing closure of gasketed joint Fig. 5. Jointing of units
noxious when blocked with traffic for any length of time. Therefore delays must be avoided.
Items that are generally provided in major modern tunnels include: A comprehensive system of illuminated signals; television surveillance; moni- toring of visibility (smoke, fumes etc.) and air pollution; footpath; emergency telephone; fire control (including equip- ment in the tunnel and means of escape between tubes in two-tube tunnels); traffic patrol vehicles; and emergency vehicles (breakdown, fire etc.).
Where a tunnel is toll collecting it is important that the toll is collected efficiently. It is normal for the toll plaza to have about three toll gates per traffic lane to ensure that vehicles are processed quickly and to allow for breakdowns and stoppages. Layout of the plaza should provide for driver- side collection and the transition from normal carriageway to toll booths
steel
rubber
tremie concrete
hood place
rock blanket
damplate
Gunite
completed joint
bulkhead removed
bed material
should be over a length of about 150m. either side of the booths. These tran- sitions form weaving lengths facilitating the divergence and convergence of traffic entering and leaving the plaza
A well-established method of cash control is for each toll booth to con- tain a keyboard-operated registration unit which relays the class of each vehicle passing and amount paid to a central record room where it is stored electronically. The registration unit also displays to the user the informa- tion relayed to the store and normally this display takes the place of a receipt.
The Hong Kong tunnel
History
The proposal for a cross-harbour link between Hong Kong Island and Kowloon has been discussed over many years. The first recorded statement was in 1901 when Captain Murray Rumsey,
the harbour master, advocated a bridge
-
across the narrowest point. At that time the population of the colony was only one-tenth of what it is today and the lease of the New Territories (which increased the area of the colony twelve- fold) was only three years old. No one could have visualised the teeming com- munity that the Mainland (Kowloon and the New Territories) supports today.
In 1948 the Abercrombie Planning Report proposed the investigation of a harbour crossing and in 1955 con- sulting engineers, commissioned by Hong Kong Government, reported on a tunnel. However in 1957 Govern- ment decided that it would not be justified in constructing a cross-harbour road link but announced that it would permit private interests to construct a toll crossing if they so wished.
In fact there were interests that had been considering the construction of a bridge as a private venture since the early fifties and in 1959 they formed the Victoria City Development Com- pany Ltd. who appointed consulting engineers (Scott Wilson Kirkpatrick & Partners, Hong Kong jointly with Free- man Fox & Partners, London) to re- port on the feasibility of a harbour crossing.
The report, published in 1961, set down the findings of a full economic and technical investigation of how best a cross-harbour road link could be pro- vided. The investigation consisted of two studies a traffic study (that was undertaken by the UK Road Research Laboratory in collaboration with the consulting engineers) to estimate the traffic that the crossing would attract, and so to determine whether it was financially viable, and an engineering study as to how the crossing might be constructed and its approximate cost.
Eventually, in 1963, the Govern- ment stated that a bridge would con- stitute an unacceptable hazard to air navigation but declared that it would be prepared to offer the company a franchise for the construction of a four-lane tunnel between Wanchai on the island and Hung Hom on the mainland. This offer was accepted and in 1965 the Victoria City Development Company Ltd. was wound up and re- constituted as the Cross-Harbour Tun- nel Company Ltd.
In late 1965 work began in earnest on the design of the tunnel and tenders were called for towards the end of 1966. Early in 1967 tenders were re- turned but, although negotiations have continued, a contract has not yet been entered into for construction of the
Far East BUILDER, June 1969
37