The 2,800-meter-long tunnel, which took three years and 1.7 billion yuan (US$204 million) to build, runs from Sancha Port in Pudong to Wusong Park in Puxi.

"The project is a milestone in Shanghai's construction history," said Chen Bin, deputy general manager of Shanghai Urban Construction Group, during a brief ceremony yesterday for the link, also known as the Waihuan Tunnel.

"The project represents the (city's) maiden use of submersion technology. It also adopted many new techniques such as noise reduction resolution and escape design," Chen said.

Work on the tunnel, which began in July 2000, was overseen by Chen's group in cooperation with Hong Kong Construction Works, the Shanghai Waterway Bureau and Shanghai Tunnel Engineering Company.

Situated along the northern stretches of the city's Outer-Ring Road, the tunnel, which includes a 736-meter-long submerged section, is comprised of three parallel tubes with eight traffic lanes.

Both of the outer tubes house three fixed single direction lanes while the middle tube has two lanes that can be adjusted to travel in either direction according to the traffic situation, Chen said.

"We have for the first time mixed rubber particles with the concrete road inside the tunnel so that noise is reduced by approximately five decibels - a noticeable reduction," Chen said.

There are two emergency corridors for passengers in between the three tubes in case of danger.

According to Chen, there is no such facility in the existing Yan'an Road Tunnel.

Currently, across the Huangpu River traffic in northern parts of the city remains slow, particularly on the Yangpu Bridge.

(eastday.com April 29, 2003)