Noise mitigation is integral to the design of the 7·4 km Lok Ma Chau Spur, a second rail link between Hong Kong and the mainland which will relieve congestion at the Lo Wu crossing point

Joey Koo Kwok Hung, Permanent Way Manager, Kowloon-Canton Railway Corp

EVER-GROWING demand for travel between Hong Kong and mainland China has generated the need for the Lok Ma Chau Spur Line, a 7·4 km branch from Kowloon-Canton Railway's East Rail at Sheung Shui to the boundary with mainland China at Huanggang. Opening in 2007 with six trains an hour between East Tsim Sha Tsui and Lok Ma Chau, it will provide an alternative crossing between the Special Administrative Region and the mainland, relieving congestion at the existing Lo Wu customs point.

Civil works on the Spur began in January 2003, and the HK$10bn project is now approximately 85% complete, with all tunnels, viaducts and 90% of the station structures finished. Tracklaying began in February 2005 and is expected to be complete next month, giving the railway systems contractors full access to complete the 25 kV electrification, signalling and communications by early June. Testing and commissioning will then begin, with passenger services starting in 2007.

The Spur Line begins at Sheung Shui station on East Rail, where the track layout has been remodelled and a grade-separated junction built between and beneath the existing lines. The first 600m of the new route then runs at grade. This is followed by 4·4 km of twin bored and segment-lined tunnels to Chau Tau, where the alignment rises to run on 2·4 km of viaduct across wetlands to Lok Ma Chau station.

Reached in just 6min from Sheung Shui, the terminus has one island platform 300m long, designed for 12-car trains, consistent with current East Rail operations. Covering an area of around 9ha, the four-level station will have duty-free shopping, customs and 140 boundary control counters similar to those at Lo Wu. Having passed through the boundary checks, passengers will leave the station via a double-deck cable-stayed pedestrian bridge over the Shenzhen River to reach Huanggang, where they will be able to transfer to a southern extension of Shenzhen Metro Line 4 which is due to open in 2007.

Provision has been made on the Spur Line tunnel for a future intermediate station to serve the Kwu Tung new town development area.

Wetland worries

The Hong Kong government had decided to proceed with the Spur Line in 1999, and construction was scheduled to start in mid-2001, but plans to route the line on a viaduct across the sensitive Long Valley were rejected by the government's Environmental Protection Department after green groups expressed concerns that KCRC would not be able to provide adequate compensation for 9·5ha of wetland that would be lost.

KCRC finally received the go-ahead from the government on June 14 2002 after proposing a 5 km tunnel costing an additional HK$2bn, but farmers feared that this might diminish the value of their land by hampering access to underground water needed for agriculture. Following assurances from KCRC that the watertight tunnels would not pollute the soil or contaminate groundwater, the Dragages joint venture responsible for the civil engineering began work on the tunnels in January 2003, using an earth-pressure balance TBM (RG 10.04 p699).

Minimising noise

The Hong Kong Noise Ordinance imposes a legal requirement on KCRC to mitigate railway noise at source, keeping it below specified levels which depend on Area Sensitivity Ratings.

The statutory requirements are very stringent, at 55dBA LAeq30 min between 23.00 and 07.00 and 65dBA LAeq30 min at other times. When imposed on a single train measured at 25m from the track centres this is equivalent to 64dBA LA(max), compared to a nominal noise level of around 88dBA from ballasted track.

To stay within the noise criteria KCRC has developed its multi-plenum system, which encompasses vehicles, track and infrastructure (RG 9.03 p581).

The EMU cars are equipped with side skirts and under-floor noise absorption, which form an under-car noise plenum in conjunction with the derailment upstand. Side plenums are formed from the viaduct evacuation walkway and a central T-structure between the tracks, which each have sound absorbent materials applied. To minimise re-radiated noise, the viaduct parapets 1·2m above the walkway are also lined with panels of sound-absorbing material.

Track design

Factors determining the choice of permanent way materials and components were safety, robustness, reliability and minimal maintenance requirements. The track is designed for our maximum EMU axleload of 18·3 tonnes and a top speed of 120 km/h. Minimum curve radius is 400m, maximum cant 125mm and highest cant deficiency 110mm.

Sonneville low-vibration track and floating slab track with soft baseplates are being used to reduce vibration transmission to stations and to cut re-radiated noise from structures. The two major trackforms provide different levels of attenuation at various frequencies across the noise spectrum found along the tunnels and viaducts.

A total of 3·6 km of floating slab track has been laid at Lok Ma Chau station and in tunnel at the site of the future Kwu Tung station. This has a resonant frequency of 12 to 14Hz with low-stiffness resilient bonded base plates of 15 to 25 kN/mm, giving a noise attenuation of 10dB in the 200 to 500Hz spectrum.

Elsewhere the transmission criteria do not require the use of FST, and 10·3track-km of low-vibration track has been installed in the tunnels and on viaduct. LVT offers low maintenance and good alignment stability, achieving noise attenuation of 10dB in the 200 to 500Hz spectrum.

There are two LVT scissors crossovers, one on a viaduct with floating slab track and one in tunnel built directly on the invert.

Track installation

The HK$185m permanent way system contract was awarded on October 31 2003 to the CHCQ joint venture of ChunWo, Henryvicy, China Railway Construction Corp and Queensland Rail. It covers track, buffer stops, derailment containment, level crossings and rail lubricators.

Top-down construction is used for the floating slab and low vibration track, a process which allows greater control to ensure that quality standards are met. It also has the environmental advantage of reducing the amount of on-site concreting works. Materials such as turnouts, rails, resilient base plates and rubber bearings were imported, with stringent tests carried out before delivery to site.

Standard 18m UIC60 rails are welded into strings up to 200m long before delivery to the worksite. They are fixed on resilient baseplates or precast concrete low-vibration track blocks, then aligned and levelled before being permanently surrounded with concrete. Daily production of 50m of LVT and 35m of FST was achieved, and there is no doubt that this could be bettered with greater deployment of resources.

The Spur's alignment makes delivery of track materials very difficult in terms of community liaison and temporary traffic management. Access to the area close to the mainland boundary is strictly controlled, with all workers needing a closed area permit. Where large volumes of material are needed, the permanent way contractor has to mobilise additional lifting points, plan carefully and, if necessary, re-sequence works following extensive liaison and co-ordination.

Construction of a new cross-boundary road led to access constraints and conflicts, and ground level civil works including landscaping and reinstatement of fishponds have also hindered access for tracklaying.

The design, construction sequence and programming had to be completely reviewed to cope with changes to the plans for a future junction with the Northern Link, which will run from KCRC's West Rail line near Kam Sheung Road to join the Spur at Chau Tau.

Working for success

KCRC has been committed to new rail projects since the opening of West Rail in December 2003, which was followed by the East Rail extensions to Ma On Shan and Tsim Sha Tsui in 2004. We believe the Lok Ma Chau Spur will be completed on time in 2007 and again within budget.

Success would not be possible without the experienced and enthusiastic professional engineers employed on the project, who must work to ensure that stringent environmental, safety and time requirements are met. Railway engineers in Hong Kong will continue to uphold their diligence and dedication to completing the coming railway extensions, including the Lok Ma Chau Spur and the Kowloon Southern Link.

Success also follows from the concerted efforts of KCRC, consultants and contractors who bring together a united team that strives to achieve the objective of providing the Hong Kong community with safe, reliable and environmentally-friendly railway services.

TABLE: Components Supplier Quantity

Turnouts Cogifer (France) 8

Resilient base plates Deklor (Australia) 13300

UIC 60 rail NSC (Japan) 1700 tonnes

Rubber bearings Trelleborg (Singapore) 25000

LVT pads Tiflex (Malaysia) 30 000

Precast concrete floating slab track from China 3200 units

Low vibration track from China 30000 units

  • CAPTION: The Spur will run from a junction with East Rail at Sheung Shui to the terminus at Lok Ma Chau
  • CAPTION: Remodelling at Sheung Shui will see one track of the Spur Line passing below the existing East Rail tracks
  • CAPTION: Installation of the floating slab track on the viaduct section before laying of the fibre concrete
  • CAPTION: Floating slab track installation in the running tunnel at the site of the future Kwu Tung station
  • CAPTION: Installation of the Sonneville LVT trackform. Gauge bars and supports hold the rails and resilient elements in position pending the laying of the track slab concrete
  • CAPTION: Flash-butt welding of the CWR in the terminal platform tracks

Le raccordement de Lok Ma Chau offre un itinéraire tranquille vers la Chine

L' achèvement du raccordement de Lok Ma Chau long de 7·4 km, entre Sheung Shui, sur la branche East Rail du Kowloon - Canton Railway, à Huanggang, sur la frontière chinoise, est attendu pour le début 2007. La ligne comporte 4·4 km en tunnel et plus de 2·4 km de viaducs. La voie doit satisfaire à des exigences strictes limitant la transmission de bruits et de vibrations; une voie spéciale anti-vibrations et un concept de dalle flottante ont été choisis. La première voie a été posée en février 2005 et les essais et réceptions doivent commencer à la mi-2006

Lok Ma Chau-Strecke für einen leisen Weg nach China

Die 7·4 km lange Lok Ma Chau-Strecke welche Sheung Shui an der East Rail-Strecke der Kowloon - Canton Railway mit der chinesischen Grenze in Huanggang verbindet soll Anfangs 2007 er?€?ffnet werden. Diese Strecke verläuft 4·4 km in Tunnel und 2·4 km auf Viadukten. Das Gleis muss strikte Kriterien bezüglich Lärm und Vibrator erfüllen, was zur Wahl von speziellem vibrationsarmem Gleis und einem schwimmend gelagertem festen Oberbau geführt hat. Die ersten Abschnitte wurden im Februar 2005 errichtet, und der Beginn der Inbetriebsetzungsarbeiten ist für Mitte 2006 vorgesehen

El ramal de Lok Ma Chau ofrece una ruta tranquila a China

Se espera que a principios de 2007 se complete el ramal de 7·4 km de Lok Ma Chau desde la ruta East Rail de Kowloon - Canton Railway en Sheung Shui a la frontera china de Huanggang. Esta línea cuenta con 4·4 km de túnel y m? s de 2·4 km de viaductos. La vía debe cumplir unos criterios muy estrictos que limitan la transmisión de ruido y vibración, por lo que se ha escogido una vía de baja vibración y un diseño de placa flotante. Las obras de vía se comenzaron en febrero de 2005, mientras que el comienzo de las pruebas y la puesta en marcha se espera a mediados de 2006