An Analysis of Urban Road Traffic Safety in Stockholm- the Use of Aggregate Time-series Model with the TRIO Programme
TEGNER G and LONCAR LUCASSI V M, Transek AB, Sweden
The DRAG-philosophy aims at creating an enhanced understanding of two aspects of mobility: the demand for road usage, and the complex interactions affecting road accidents. The notion is based on a three step approach, risk exposure, accident rate and its
The DRAG-philosophy aims at creating an enhanced understanding of two aspects of mobility: the demand for road usage, and the complex interactions affecting road accidents. The notion is based on a three step approach, risk exposure, accident rate and its severity. A data base has been created for the County of Stockholm with a broad spectrum of explanatory variables, such as socio-economic factors, laws and regulations, road and public transport data, vehicle fleet data, climate data and other related information aiming at explaining the development of road traffic and road accidents ex post. A special statistical programme package, called TRIO 1 has been used in the analysis.
The demand model is estimated on aggregate time series data for the whole area (in this case Stockholm County). The idea is to explain both traffic volumes (vehicle kilometres, vkms) and road accidents by a wide spectrum of explanatory variables by exploiting the vast variation in the monthly data set. This technique is called DRAG and stands for: "Demand for Road use, Accidents and their GraviO/" , and is developed by professor Marc Gaudry at the Transport research Centre at the University of Montreal in Canada.
In our application of the DRAG approach in the Stockholm region, the following time series models have been carried out on a monthly basis for the period 1970 - 1995:
* an EXPOSURE model of total road mileage (vehicle kilometres) for petrol passenger cars
* a FREQUENCY model of total number of road accidents with personal injuries and deaths
Association for European Transport