Mass. Gen. Laws ch. 160, § 84

A railroad corporation may purchase, or take in the manner provided in the preceding section, from time to time, any lands or rights belonging to any other railroad or other public service corporation not necessary for the business of such corporation at such time or in the reasonably near future, provided that this section shall not authorize it to acquire by eminent domain any part of the location or right of way of any other railroad or street railway company except such lands or rights as the department adjudges necessary for the support, construction and repair of bridges or other methods of crossing such railroad or street railway.