Urban agglomeration benefits from public transit improvements: Extending and implementing the Venables model

In the Venables model, commuting costs determine the size of the Central Business District (CBD) workforce and thus the productivity and wage premium generated by agglomeration economies in the CBD. Improvements in public transit modes increase numbers willing to commute to work in the CBD, and generate additional productivity gains. The resulting efficiencies can greatly exceed estimates of direct travel time savings from the PT innovation. The Venables model is operationalised and extended, and applied illustratively to two actual PT innovations in Auckland: improved bus lanes, and improved rail service.