  Predicting how changes to the urban environment will affect town centre
vitality, mediated as pedestrian flows, is important for environmental, social
and economic sustainability. This study is a longitudinal investigation of
before and after urban environmental change in a town centre and its
association with vitality. The case study baseline is Cardiff town centre in
2007, prior and after major changes instigated by re-configuring Cardiff public
and quasi-public street layout due to implementation of the St David's Phase 2
retail development.
  We present a Multivariate Hybrid Spatial Network Analysis (MHSpNA) model,
which bridges the gap between existing Spatial Network Analysis models and four
stage modelling techniques. Multiple theoretical flows are computed based on
retail floor area (everywhere to shops, shop to shop, stations to shops and
parking to shops). The calibration process determines a suitable balance of
these to best match observed pedestrian flows, using generalized
cross-validation to prevent overfit. Validation shows that the 2007 model
successfully predicts vitality as pedestrian flows measured in 2010 and 2011.
This is the first time, to our knowledge, that a vitality-pedestrian flow model
has been evaluated for its ability to forecast town centre vitality changes
over time.
