Metros under construction around the world

Many cities are tackling their urban congestion problems by utilising under ground space and developing or expanding underground railways or metros,Thi s paper presents metro projects currently being constructed in four major w orld cities: Los Angeles, Copenhagen, Bangkok and Toronto. An overview of e ach project is presented together with illustrations of the tunnelling proc ess and station development. The major design issues common to all the proj ects were settlement and groundwater control, Other issues specific to part icular projects, such as earthquake allowance or maintenance of traffic flo w, are also discussed, The aim of the paper is to show the infrastructure d eveloping below our cities and briefly outline some of the complex geotechn ical problems faced in the construction of these essential facilities.