It’s been a long time coming but high-speed rail connecting Hong Kong with mainland China will soon be a reality as construction on the first underground tunnel from Shenzhen to Hong Kong is now complete.

The 3,886 meter-long tunnel runs from Shenzhen, Guangdong all the way to Mai Po District in Hong Kong, laying the tracks for high-speed rail travel between the two destinations.

Upon completion, the Kowloon-Shenzhen high-speed line will connect with the already operating Beijing-Shenzhen line. The new line is expected to cut travel time between Hong Kong and Beijing from 20 hours to just nine.

The joint effort to build the railway line was notably constructed under two different standards: Chinese and European, the latter of which was used for the Hong Kong section.

Wu Xiangong of the China Railway Group Company gushed over the opportunity to work with two different standards:

We realized seamless joint Chinese and European standards in the two rail tunnel sections and we can use the experiences to build on future opportunities of tunnel construction in Europe and even America. And through this practice we can find some benefits to the ‘going global’ strategy.

Previous estimates had put the railway’s completion to be in 2016.