Swapping left and right on the Tuen Ma Line

Road and rail traffic in Hong Kong usually moves on the left, but the recently completed Tuen Ma Line is a little different, with the eastern section running on the right, and switching back over to the left in the middle of Kowloon. So why does such a strange situation exist?

In the beginning

Hong Kong’s first railway line was single track, so there wasn’t a side for trains to take.

Photo via this blog.

But following the 1980s upgrade that duplicated and electrified the Kowloon Canton Railway, they had to pick a side – left, the same as road vehicles.

And so this remained the standard until the opening of the Ma On Shan line in 2004 – a 11.4 km long branch line serving nine stations in the Sha Tin District.

Ma On Shan line viaduct parallels the Shing Mun River

This line branched from Tai Wai on the East Rail line, where passengers could connect with trains headed under Lion Rock for Kowloon and Hong Kong Island.

Train arriving into a crowded platform

So the decision was made for trains on the Ma On Shan Line was run on the right.

Wu Kai Sha bound train arrives at Ma On Shan station

Allowing a cross platform interchange for passengers at Tai Wai.

MTR diagram

Enter the Sha Tin to Central Link project and the Tuen Ma line

After many years as just a proposal, in 2007 the Sha Tin to Central Link project was given the go-ahead, extending the East Rail line under Victoria Harbour to Hong Kong Island, and join the Ma On Shan line and the West Rail line into a single east-west corridor across the New Territories and Kowloon.

Shatin to Central link work site at Diamond Hill station

The latter connection was a new underground railway known as the “Tai Wai to Hung Hom section” of the Sha Tin to Central Link project, and included 11 kilometres track and six new intermediate stations.

The only problem – trains on the West Rail line line ran on the left like the rest of Hong Kong, not on the right like the Ma On Shan line.

Tuen Mun bound train approaches at Tin Shui Wai station

So the solution?

Triangle junction at Ngan Wai, with the West Rail viaduct in the background

No – not an at grade crossover – but some twists in the new section of underground tunnel.

The railway alignment runs from Sung Wong Toi station below Ma Tau Chung Road/Ma Tau Wai Road towards the west, reaching To Kwa Wan station. After leaving To Kwa Wan station, the alignment passes Ko Shan Road and joins the Ho Man Tin station at the intersection of Fat Kwong Street and Shun Yung Street.

As new station of line was built under narrow roads, with cut-and-cover station boxes connected by tunnels dug with a mixed ground TBM.

Tunnelling works for the Shatin to Central Link on Ma Tau Wai Road, To Kwa Wan

So the decision was made to build To Kwa Wan Station as a ‘stacked’ three level station.

MTR photo

Concourse on top, then platform 1 to Tuen Mun, and platform 2 to Wu Kai Sha at the bottom.

MTR diagram

The stacked tunnels splitting apart into two side-by-side left running tracks before reaching Ho Man Tin station, and into two side-by-side right running tunnels at Sung Wong Toi station.

MTR diagram

A clever adoption of what was otherwise a constraint placed on the design.

Footnote: what about the rail links into China?

Over in Mainland China cars drive on the right, so vehicles crossing the border from Hong Kong need to swap sides. But what about trains crossing the border to Lo Wu?

They get stay on the left hand side – because China Railways also uses left-hand running across their national network.

Overtaking a HXD3C class hauled passenger train on the 'old' Shanghai-Beijing railway

Further reading

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