rescue workers on tuesday began the process of inserting wide steel pipes through the rubble of the collapsed under-construction tunnel on the chardham route to bring out the 40 labourers trapped inside for two days now, officials said. the plan was to push through 900-mm diameter sections of mild steel pipes -- one after the other -- into the rubble using drilling equipment and create an escape passage for the workers, who officials say are safe and being provided with oxygen, water, food packets and medic