NEW DELHI: Approval of National Green Tribunal ( NGT ) to build two bridges on the Yamuna , providing 34 hectares land to Delhi forest department for compensatory afforestation and rehabilitation of 500-odd slums are some of the hurdles that NHAI has to overcome before work can even start on the first part of this corridor.The foundation stone for this ambitious 50-km project was laid by Prime Minister Narendra Modi in December.For fast execution, the government had divided it into three parts. So far, NHAI has awarded work for the first (Nizamuddin Bridge to Delhi border) and the third (Dasna to Hapur) parts. The successful bidders have tied up funds. However, NHAI is struggling to bid out the second part -Delhi border to Dasna -which is the most congested portion. “The lowest bidder had quoted very high cost and it could not be accepted. So, we have re-tendered the package,“ an NHAI official said.To expand the existing highway in the Delhi portion, NHAI has to construct two bridges, one on each side of the existing two bridges on Yamuna. Sources told TOI that a 2014 NGT order restricts any construction on Yamuna floodplains without its approval. “We have got the study completed by IIT-Roorkee and environment impact assessment has also been done. We will submit them to NGT's expert committee,“ an official said.The second issue is cutting down nearly 3,500 trees. Since Delhi has a special Act, NHAI has to provide 35 hectares for compensatory afforestation and also has to pay for plantation of 10 trees for each tree cut. Sources said NHAI is in talks with DDA to get the required land and a solution is likely by next month.The third hurdle is rehabilitation of about 500 slums along the existing highway near Patparganj Sources said Delhi government wants NHAI to pay Rs 20 lakh for each slum so that they can be allotted flats. “We are negotiating and a solution will be found soon,“ the NHAI official said. Sources said there was no hindrance in the Delhi Border-Dasna stretch and tree cutting was already on. Nearly 50% tree cutting was over.In the case of Dasna to Hapur stretch, NHAI is hopeful of getting forest clearance by next month.