contracting authority or public undertaking which pursues one of the activities referred to in Articles 3 to 7 of Directive 2004/17/EC (e.g. provision of gas, electricity, transport, postal services, water, exploration for or extraction of oil, gas, coal or other solid fuels, provision of airports) OR any public or private entity which orders the design and/or construction or the renewal or upgrading of a rail subsystem under Directive 2008/57/EC on the interoperability of the rail system within the Community