One of the ongoing problems of urban archaeology is the fact that it is very expensive. Because sites are often deeply buried under the modern city and because they require the movement of great amounts of soil, urban excavations require the use of expensive equipment, such as backhoes and front-end loaders, to remove the overburden and to truck it off the site. Furthermore, cities by definition have dense populations and have undergone intensive use of the land. These facts make them stratigraphically very complex, and of course sites with complex stratigraphy take longer to excavate. In addition, because they lived either during or after the industrial and consumer revolutions, the peoples of modern cities have Many more things - a much denser material culture - than people of earlier times. This in turn means that collections from modern urban sites are extremely large, and such large collections are extremely expensive to process, analyze, store, and curate. Therefore the archaeological study of the modern city really only began in earnest after the development of heritage and environmental legislation that required that developers (in some cases) pay for archaeological projects on the land they were about to develop before the sites on that land were destroyed (see Antiquities and Cultural Heritage Legislation).
The archaeological study of the modern city often involves the examination of large sites, sometimes made up of several city blocks, and therefore required a new methodology. The first step is the careful examination of many forms of documents recording the history of the property. If the areas involved are enormous, a sampling plan with a rationale needs to be developed.
The second step is a phased field strategy whereby parts of the site are sampled through excavation. This is then followed, if warranted, by recovery or mitigation, where a large sample of important deposits is excavated prior to their anticipated destruction. If destruction can be avoided, these remains may be kept intact and, in some cases, small segments of the site are preserved or restored and placed on exhibit for the public. Usually, however, urban excavation is performed in conjunction with development and thus unexcavated deposits are destroyed.
The regulations that require archaeological evaluation before construction in urban areas vary from country to country. Some urban centers have plans in place to protect and recover archaeological resources. Much of the legislation in the United States is modeled on the National Historic Preservation Act of 1966, which states that archaeological sites have to be considered whenever there is federal involvement in a development project. This legislation is mirrored on the state and the local levels. Some American cities have formal programs which evaluate the impact of new construction (notably Alexandria, VA), while others have agencies (such as New York’s Landmarks Preservation Commission) that are more or less effective at protecting archaeological sites, usually by defining their value rather narrowly (i. e., in some cities only seventeenth - and eighteenth-century sites are deemed worthy of protection).
England is, in many ways, the country with the greatest protection for heritage resources. Their procedures, PPG-16, attempt to balance the priorities of development with those of heritage, and employ long-range planning to minimize conflict. They have an intensive archaeological program focused on 30 major
Cities. An effort is made to emphasize the potential value of archaeological remains and not just to view them as impediments to development. One significant tool which has contributed to urban archaeological practice there is the use of Urban Archaeological Data bases, especially in cities such as York, Winchester, Newcastle-on-Tyne, and Lincoln. These are based on geographical information systems (GIS) and consist of a series of layered maps, each of which records known sites from a different time period. Thus, when development is planned, a predictive model can be generated that rapidly reveals what is known about the project area so that it can be evaluated, for example, to see if there are known historic structures or archaeological sites there, or if archaeological work has already been done in the area. These databases may also include documentary information that has been collected previously, such as leases or other land records. This type of database will presumably come to be used in other cities in other parts of the world.
World History
