There has been a lot of talk recently in UK tunnelling circles about Kuala Lumpur’s ambitious 9.7km long single-tube, Stormwater Management and Road Tunnel, planned for a construction start mid next year (see p11). The ‘pretty much certain to go ahead’ project is a great example of not only innovative design, incorporating a road and stormwater tunnel, but an adventurous concept in combining established foreign expertise with a local ‘will to learn’, that will surely increase the experience of home grown talent for future domestic projects.
Basically, the client, Gamuda/MMC under the Malaysian government, has split the tunnel into two drives from a central shaft, each to be built using a 13.2m diameter slurry TBM. The difference is, the longer of the two drives has been awarded to the vastly experienced German contractor Wayss & Freytag, whilst Gamuda, a relatively inexperienced tunnel builder, has decided to bore the other drive itself. With a team line-up of Wayss & Freytag (as good as working next door), Herrenknecht TBMs and UK consultant Mott MacDonald overseeing proceedings, the chances of smooth progress suddenly become more realistic and the introduction to the hazardous world of tunnelling considerably less intimidating. The construction experience should, barring unfortunate incident, place Gamuda in pole position for winning other works in Malaysia’s future lucrative market. Everybody has to learn their trade somewhere, so why not bring in the experts to lend a helping hand in the early days? It’s potentially a no lose situation for all parties.
Also worthy of mention is a design that sees some of the huge costs associated with boring a large diameter stormwater tunnel offset by earmarking the middle section as a tolled road tunnel. The central few kilometers of the tunnel will be accessible from the surface via bifurcations allowing traffic to join the structure mid-way along its alignment. The mostly minimal seasonal flows will be routed under the road deck, but when the once-twice envisaged yearly storms require the full diameter, the road will be closed and the full tunnel used for overflows, so all eventualities should be covered. This really is a good example of getting the most out of a necessary piece of civil engineering. Costs are minimised whilst experienced is maximised!
With the high global expense associated with tunnel construction often working against the realisation of some schemes, this method of ‘killing two birds with one stone’ should be looked at in more detail in all corners of the world to ensure underground construction stands as fair a chance as possible of being the client’s method of choice.
Tris Thomas
