SIMPLAN: A SIMplified PLANning Model

The SIMPLAN modelling suite comprises four modules for informing the process of city planning. The first module (called TAM) is concerned with analysing the evolution of the spatial structure of a city. The second module (called RLM) is an econometric residential location model that uses average housing rents as part of the generalised cost in a gravity-type allocation function and currently deals with work trips. The work trips are then split by mode using a multinomial logit modal split model (called MSM), which forms the third module of SIMPLAN. After appropriate calibration, SIMPLAN can be used to test alternative planning policies for a future/horizon year, with appropriate employment, dwelling floorspace, and transport inputs. The fourth module (called ASM) is concerned with assessment of alternative planning policies against key economic, environmental, and social indicators. The core of SIMPLAN is formed by the RLM and MSM modules. This paper discusses only the calibration of the RLM and MSM for a base year (2001) for the city of Ahmedabad, India. Applications of TAM and ASM to Ahmedabad are discussed in separate papers and not reported here. However, a schematic diagram showing the interrelationship between the four modules is included. SIMPLAN is developed in a spreadsheet environment, with all key operations controlled by a visual interface using subroutines written in Visual Basic Application code. This creates a user-friendly graphical interface that makes the model simple to understand and operate by local planning agencies, and, in addition, provides them with the flexibility of updating the model as and when new data are available or a new round of the census is conducted.