Commuting towards City Centres: A Study of Population and Employment Density Gradients in Liverpool and Manchester

Abstract

This paper examines the relationship between the importance of commuting in various directions and the dis- tance from the centre of a large city. A form for this relationship is proposed, largely on the basis of deductive reasoning from an inspection of the population and employment density gradients within towns. Using statistics gathered from census publications for the period I921 to I966, the propositions are tested through a study of the Liverpool and Manchester metro- politan areas. It is concluded that there is strong evidence that employment density gradients are in the form of a cubic exponential function. The concentration of employment towards the centres of towns, and the very low density of employ- ment towards the periphery ensure that this function is statistically significant. Although there is substantial evidence that commuting towards the centre is unusually important from both the inner city and the periphery and is relatively low from other parts of the city regions, there is little statistical verification of this double-peaked or quadrinomial pattern. The evolu- tion of commuting patterns around Manchester and Liverpool is described. THIS paper discusses the relationship between distance from city centres and the directional distribution of journeys-to-work. The discussion is founded upon the characteristics of popula- tion and employment density gradients around cities. No attempt has been made to improve the existing descriptive and explanatory generalizations about population density gradients, but it is hoped that the work provides some advances in our knowledge and understanding of urban employment distributions. The paper's propositions have been derived from both deductive reasoning and a review of a small number of studies of employment distributions within towns. In later sections, it is suggested that by simply aligning these two gradients, zones around the city of job surplus and deficiency may be identified from which a number of features of urban commuting patterns may be deduced. All the suggestions are tested for their applicability to the Manchester and Liverpool conurbations since 1921; the results being presented and evaluated towards the end of the paper. It can therefore be seen that the paper's objectives are largely theoretical, as it is hoped to show that meaningful point-in-time and dynamic generalizations about the concentric structure of cities may be extended from population to kindred distributions. It is also argued that the comparison of such distributions suggests many other features of city structure which are of initial theoretical interest and, dependent on their wider verification and no doubt modification, have obvious applications in the analysis and prediction of urban areas for planning purposes. At this point it is worth making clear that this study is concerned only with aggregates of the employed population and of employment and not with the density gradients of individual social classes, age-groups or categories of jobs. It is recognized that there are pronounced divergencies from the overall pattern among these groups, but, at the same time, it is believed that it is most important to assemble clear evidence about the general pattern before the significance of such deviations can be fully understood. A similar argument is used to justify the lack of attention in this paper to sectoral variations around the city centre.