No_10_October_1969 — Page 33

Expressway is basis of

Civil engineering & public works

Singapore road planning

AS THE degree of industrialisation in Singapore intensifies, the most obvious problem confronting the Republic is rapid transportation.

The problem grows with the number of persons moving into the newly-developed satellite towns and the central areas where Urban Renewal forges ahead. As in other regions, the family car plays a major role in the everyday life of the working popula- tion and distance is considered not in terms of mileage but rather of time.

To cope with the increasing traffic load, the Singapore Public Works Department has embarked on a multi- million dollar programme to provide a new system of streets and highways based on a limited-access highspeed expressway connecting the city area with the industrial estates and satellite towns.

The expressway has been designed to serve primarily as a main distributor for these specific areas and to reduce cross-movements within the city. Trumpet and semi-clover leaf inter- changes are being constructed for access to the satellite towns from the expressway and at intersections be- tween the expressway and major arterials.

In accordance with specified re- quirements, the trumpet interchanges which are under construction at the northern access and southern access to the Toa Payoh satellite town pro- vide a two lane undivided carriage way, 24 ft. wide between the kerbs and flanked by two 3 ft. wide service footways.

Another interchange under con- struction is at the major road inter- section with the expressway, Jalan Toa

Flyover at Toa Payoh

Payoh, Whitley Road and Thomson Road. This flyover is a semi-clover leaf type which provides an overall width of 76 ft.

All the flyover structures give a minimum 16 ft. 6 in. height clearance between the soffit of the beam and the road surface. The main structural elements are prestressed concrete beams of 68 ft. and 120 ft. span. The deck is of cast-in-situ concrete slabs.

The prestressed concrete beams are supported on rubber-pad bearings which permit limited rotation, trans- verse, and longitudinal displacement during and after construction. The flyovers are mainly supported on steel piles, an exception being the northern access to the Toa Payoh satellite town from Braddell Road flyover structure which is supported on precast rein- forced concrete piles.

Far East BUILDER, October 1969

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