Renewing Singapore's urban infrastructure - Recycled aggregates can make the gradeThis advisory paper identifies and explains those specific constraints relating to designing within existing London Underground (LU) stations and adjacent to the track and theresulting preferred method of construction. Key design parameters are examined and the comparative significance of other disciplines is discussed. The main outcome being that in heavily restricted sites with exacting design and operating tolerances from lifts, escalators, and track, knowledge of plant operating requirements and their effect on design is essential. These parameters are examined along with the significance of other disciplines. R . G. Wodehouse, CEng, FIStructE Senior engineer formerly with Tube Lines Limited, a TfL company