10 A key role for the Arbiter is to determine the "economic and efficient" price for the delivery of services. This involves the concept of a notional Infraco which acts in an economic and efficient manner and in accordance with good industry practice, and has the same sub-contracting and funding arrangements as the actual Infracos. There is a separate notional Infraco for each Infraco to reflect the differing structures and obligations of the three Infracos - in the first 7½ years, Tube Lines intends to let all its major contracts competitively, while Metronet's main suppliers are members of the Metronet consortium, with the PPP award process acting as a competitive tender for their sub-contract prices. The Arbiter determines the future service charge based on his estimate of what the cost "should be" for the respective notional Infraco.
11 According to the contracts, good industry practice includes:
■ establishing and maintaining whole life asset planning and maintenance regimes; and
■ understanding the degraded operation of complex systems so as to ensure controlled degradation.
12 "Economic and efficient" can mean different things in different contexts, and at different times as good industry practice changes. The Arbiter therefore has discretion over what he considers to represent "economic and efficient" in any particularly situation.