ABSTRACT:

This paper describes the design and construction of a 12m long underpass project and the problems encountered during construction. The underpass has an opening of 9m × 5m passes through an existing railway embankment. The underpass is located at Jalan Sultan Salahuddin in the city of Kuala Lumpur, Malaysia. Construction of the underpass involves the use of micro tunnelling of sixty-eight numbers of mild steel pipes to form the tunnel support beneath the railway embankment. The pipes were connected to each other using special connectors. The earth underneath the shell was then removed using excavators or manually. The earthworks were carried out in sections, with the top shell temporarily supported by six portal frames resting on good ground. The portal frames consist of two universal I-beams of 600mm × 300mm at the top, bottom and at the sides. Another two numbers of 300mm × 300mm universal columns were also fixed at the middle of the frame. Close monitoring of the movement of the embankment was carried out in order to ensure that there is minimal settlement of the railway tracks. Monitoring were also carried out to detect movements of the existing bridge abutments and orientation of the pipes during installation.

INTRODUCTION

The underpass project was initiated to provide and additional two lanes of road to ease the congestion of motor vehicles that occur due to a nearby roundabout. The underpass project also helps to increase safety and reduce accidents occurring to school children as there is a lot of activity near a nearby school located near the roundabout. The underpass project is located at Sultan Salahuddin Road in the city of Kuala Lumpur, Fig. 1. The underpass is 12m in length passes through an existing railway embankment. The underpass has an opening of 9m by 5m.

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