PPP contracts typically last for thirty years, with relatively limited opportunities after contract signature to test or re-tender the total price paid by the authority over the life of the contract (see Section 6.3 below on benchmarking). It is therefore vital for the authority to satisfy itself that it has achieved the best possible value for money at the point it lets the contract. We looked first at the number of bidders for each project, which provides a good indication of the authority's success in creating effective competition (Section 3.3.1). We also looked at price movements in the period after the authority had chosen its preferred bidder (Section 3.3.2). During the preferred bidder stage, although the authority generally has the right to re-introduce the second placed bidder, it rarely exercises that right. Competitive tension is greatly reduced, and it is important to ensure that price movements are closely monitored.