The widening of the Mumbai-Goa highway will re quire around 31,000 trees to be axed. These trees line a length of 91 km, which is part of the 366 km stretch of the NH-66 that will be widened into four lanes. With transplantation not easy given the terrain of the highway, experts suggest saplings be grown in nurseries and then planted along the highway. Environmentalists are also worried about soil erosion and threat to the entire eco system. PWD officials said the tree cutting would start once land acquisition for the project is completed.