subcontractor shall conduct its operations and ensure that those of its subcontractors are conducted, so that all operations necessary for the execution of the work shall be carried out so as not to obstruct or interfere with the convenience or lawful activities of contractor, the owner, other contractors engaged in the site and any third persons, or the access to, use and occupation of roads and footpaths to or on properties whether in the possession of contractor or of and other person or entity. where such access must be unavoidably blocked, subcontractor shall provide equal means of ingress and egress.