as planned, often with the requirement that archaeologists are on-site providing a watching brief. If potentially significant remains are found, construction may be delayed to allow for evaluation of the site or sites found within the impacted area. This is done to determine the archaeological site's true significance. If archaeologists determine the site contains important/significant cultural remains, the adverse effects on the site must be mitigated. Site mitigation can involve avoiding the site through redesigning the development or excavating only a percentage of the site. In the U.S., these restrictions involve any federal project involving the possible disturbance of cultural resources and can also extend to state and private developments if they involve public waterways or federal funds. If archaeologists determine the site contains highly significant cultural remains, the adverse development effects on the site must be mitigated through a structured programme that is often long and expensive. Mitigation can include preservation by record i.e. the site is destroyed by archaeological excavation rather than by the development and meticulous recording transfers the physical traces in the earth to information in archives. Mitigation also includes construction techniques which ensure that archaeological remains are protected in undisturbed parts of the site or even underneath the development. An example of this type of mitigation is the Viking remains at York. Important sites are designated as being protected by the state so that no development at all can take place, and governments also recommend the most important sites to be recognised as World Heritage Sites. The effect of CHM on archaeology CHM has been a mixed blessing for archaeology. Preservation legislation has ensured that no valuable site will be destroyed by construction without study, but the work of rescue archaeologists is sometimes controversial. Some academic archaeologists do not take archaeological rescue or salvage work seriously because of its emphasis on site identification and preservation rather than intensive study and analysis. Where archaeology is motivated by proposed development, the archaeological contracts are placed through a bidding process. The choice of archaeological contractor typically lies with the developer and there is little incentive to prevent the company responsible for construction selecting the bid with the lowest price estimate, or shortest investigation time, regardless of the archaeological merits of the submitted bids. The impact of archaeological rescue and salvage work has been considerable; given the large amount of construction, and that the bulk of archaeological work in