Amid the roaring noise of galvanised machines warming up for a long night ahead, the yellow barricades are shifted or removed —only to be restored to its original position before dawn to accommodate the morning traffic. Lights mounted in every nook and corner of the site are switched on.

The action, of course, takes place 15 feet above the busy road every night. On Vikas Marg, where the elevated section of the Delhi Metro is supposed to cut through East Delhi by December 2009, the night shift that begins at 10 pm is the most crucial and productive.

Night means less traffic and less hindrance for transporting boulder-like concrete structures, called segments that weigh about 40 tonnes, on trailers that are not allowed to ply during the day, say site engineers. “We usually set the stage by doing the preparatory jobs during the day,” one of them explains. Each segment is joined to the other to create a ‘span’ between pillars—called piers. The tracks are then laid on the span.

As the trailer from Metro’s shed at Sarai Kale Khan arrives at the spot, workers take position, guided by the colour of their ‘hard hats’ or helmets. The ones with the yellow helmet are workers who carry out the civil work and operate machines, those with the blue and red ones are supervisors for the contractor. Workers wearing green helmets ensure that the safety norms are ensured at every stage. The boss — the DMRC engineer — gets to wear a white helmet.

As the crane begins to lift the segment, operated by one worker inside and guided by another on ground, five workers hurriedly apply a chemical concoction called the ‘glue’ to paste the segment, the last one of the nine-metre span and also the heaviest one. The site engineer explains: “Synchronisation and discipline is the key factor here. Every step is time bound. Our men have only 60 minutes to lift the giant structure and paste the segment. Then stressing the entire span using hydraulic machines is another task.”

Around 12 kilometres away, the Metro construction site at the INA Market is quieter and 20 feet below the road. This is the underground Metro station on the Central Secretariat-Gurgaon line and the 100-odd workers in yellow hats building the ceiling of the underground Metro station resting on a giant iron-lattice resemble bees working through a beehive.