Construction of Beijing airport light rail line reached a milestone this week with the completion of a superstructure, according to the municipal rail management company.

Workers finished the construction of the superstructure at the Siyuan bridge on the fourth ring road on January 9, and will start to lay the tracks in March, according to the company.

Construction of the railway is expected to be completed in April 2008 and trial operations are due to begin in July of the same year.

With a total length of 28.1 kilometers, the track will run from Dongzhimen, on the northeast corner of the second ring road which encircles the downtown area, to the Beijing Capital International Airport in northeast Beijing.

Four stops will be built along the line at Dongzhimen, Sanyuan Bridge and two terminals (T2 and T3) of the airport.

The rail is a key project for the 2008 Beijing Olympic Games.

The rail's highest speed will be 110 kilometers per hour, bringing the journey from Dongzhimen to the airport to under 20 minutes.

Beijing has two subway lines and two light rail tracks, totaling 114 kilometers.