5. Cost components in archaeological LCP studies

Table 1 lists the cost components that were taken into account for archaeological LCP studies (published until 2009) dealing with rural areas. In addition, the components proposed in two popular GIS books for archaeologists are shown.

Table 1: The cost components used in the archaeological LCP studies analysed
PublicationSlopeLand cover; soilWater: barrier or transportVisibility, viewshedsAttractors, taboo zonesExisting routesOthers
Barbe 2007 X X X
Batten 2007 X
Bell and Lock 2000 X X
Bell et al. 2002 X X
Bellavia 2002 X X
Bevan 2011 X X
Branting 2007 X
Chataigner and Barge 2008 X
De Silva and Pizziolo 2001 X
Eichfeld 2005 X
Ejstrud 2005 X X
Fábrega Álvarez and Parcero Oubiña 2007 X X
Fiz and Orengo 2008 X X X
Gietl et al. 2008 X X X
Hare 2004 X
Herzog 2009b X X
Herzog 2010 X X
Howey 2007 X X X
Kantner and Hobgood 2003 X
Llobera 2000 X X
Madry and Rakos 1996 X X
Parslow 2009 X
Pecere 2007 X X
Podobnikar et al. 2004 X
Polla 2009 X
Rahn 2005 X X X
van Leusen 2002 X X X
Vermeulen 2006 (X) X X
Whitley and Burns 2007 X X
Whitley and Burns 2008 X X X
Zakšek et al. 2008 X X
Conolly and Lake 2006 X X X X X
Wheatley and Gillings 2002 X X X X X

Chapman's GIS book (2006) is omitted from Table 1 owing to its limited impact on the community and mainly because of its lack of detailed analysis concerning LCP methods. Most studies in Table 1 are based on the analysis of slope, often combined with some other component. The only exception is the LCP analysis by Eichfeld (2005), but his study area is extremely flat. Walking experiments on an ancient road in Japan by Kondo and Seino (2010) suggest that the slope of the terrain is the most important factor influencing both walking speed and heart rate, whereas field of view and roadbed condition play a minor role. Contrary to most geographical studies on path selection (Pingel 2009), avoiding steep slopes is considered essential in most archaeological LCP publications. Rahn (2005) laments that most cost-surfaces used in cost path analysis in archaeology are slope-based, and that the land is treated as a uniformly compacted asphalt-like surface. However, other authors (e.g. Batten 2007) argue that building the initial model on reliable elements of the landscape such as slope is a good starting point. A model is only an approximation to past reality and it seems reasonable to iteratively refine the model and to compare the LCPs to the archaeological record after each step. With overly complex models like that proposed by Barbe (2007), the impact of each cost factor on the LCP cannot be assessed.

A cost function for Roman roads that does not fit well into the categories shown in Table 1 is presented by Vermeulen (2006), who uses the DEM to identify topographic depressions and hilltops because, according to his model, hilltops and depressions influence the Roman roads so that they deviate from the ideal straight connection.