A Population–Employment Interaction Model as Labour Module in TIGRIS XL

24-04-2013 | Publication

This paper looks at the integration of a population–employment interaction model in the TIGRIS XL model framework. TIGRIS XL is an integrated land-use and transport model which is actually a system of modules (sub-models) that allows dynamic interaction between these modules. Currently, the population module responds to lagged changes in employment, and the employment module responds to contemporaneous changes in population. According to these modules, the change in population mainly drives the change in employment — an assumption which, given the strict Dutch restrictions on population location, is not entirely unrealistic.

However, in this paper, we argue that this assumption is too harsh, and that sectoral employment change may be more dependent on employment changes in other sectors than on changes in population. We, therefore, tested and estimated such relations, which led to the conclusion that indeed, for certain sectors, the employment dynamics in other sectors are more important than population changes. The adapted version of the labour module was included in the TIGRIS XL framework and assessed by looking at a (stylised) case study. This study concerned the doubling of the size of the new town of Almere, located 20 kilometres east of Amsterdam. In the period up to 2030, about 60,000 additional dwellings are to be built in this town, and an additional 100,000 jobs will be created. The accessibility benefits of a particular land-use planning variant with a tailored public transport investment alternative are examined for the new labour module in the TIGRIS XL model. For the construction of 60,000 dwellings, the model predicted that the number of additional jobs would be much lower than 100,000. This overall conclusion is in line with previous applications. However, at a more detailed level the population–employment interaction model projected population changes to be slower and to take place over shorter distances. The explicit modelling of relationships between sectors showed that employment cannot be moulded that easily into population changes.