18.02.13 - Under a mandate from Swiss PostBus, the Transportation Center of EPFL analyzed attendance data from this enterprise known for their yellow buses. The result? An increase in the frequency of lines can have double the impact on their use!

Matching supply to demand is a real headache for any enterprise. This is even more the case for public transportation. Is it enough to simply increase the frequency of certain lines for the usage rates to follow suit? In what areas do they face constraints and challenges related to supply planning? The issues are particularly relevant to the evolution of mobility and the choice of a mode of transport that inhabitants of the city and the countryside face today.

As part of a research project on combined mobility launched in 2009 by PostBus and the Transportation Center at EPFL, three affiliated laboratories (CEAT, LASUR, and TRANSP-OR) have addressed these issues. The researchers analyzed data collected over four years (2007-2010) on 147 lines in three areas served by PostBus: Valais, the east, and the north of the country.

The results are clear: an increase in the rate of a route almost always results in an increase in passengers that exceeds the proportional increase. For all lines analyzed, a 7.5% increase in supply leads to an increase in passengers of nearly 15%. In addition, the study shows that not only does PostBus have an image that is friendly, rural, and touristic, but also it is an integral link in the chain of transport-oriented urban centers and the train.

Role of Service

During the study period of 2007-2010, PostBus increased the number of passenger-kilometers – an index that measures both the number of customers and the distance traveled – by 7.3%. The study shows that with the high-speed lines, adding an additional carrier adds new passengers on lines whose rate is low. In addition, commuters are more likely to take a yellow bus because it runs at least once an hour on a given line. The density of the population in the vicinity of a stop and the importance of the line in the regional context are also determinants of commuter frequency. In contrast, the employment rate near a stop showed no significant impact.

The researchers were also able to measure the effects of changes in behavior in terms of mobility and the recent PostBus strategy. The metropolitan areas with feeder lines in railway stations and lines heading to the center experienced the largest increase in passengers (+15% and +19%, respectively). In addition, on these lines, the closer the train station, the higher the number of passengers. Overall, the company has also benefitted not only from a political environment that favors the development of public transport in Switzerland, but also population growth and urban expansion.

Stark Regional Disparities

If there is a positive relationship between frequency and usage, it is neither linear nor constant. The sample shows wide disparities across regions and analyzed contexts. In the areas of St. Gallen and around Sion, for example, the number of passengers increases despite a constant supply of buses. At Brig, a minor adjustment in what is offered is rewarded with a surge of customers. However, Uznach and Basel did not experience an increase in passengers, despite an increased investment exceeding that in Brig. In the areas of Aarau and Frauenfeld, the number of passengers increased by 30%, despite an investment that was smaller than that in Basel. These regional differences are partly attributable to the local political environment, the presence of fare networks, the practice of preferential tariffs for tourists, or structural changes, such as the opening of schools or new infrastructure.

Finally, scientists have evaluated the potential of improving PostBus. In rural and suburban areas where the transportation company is present, 70% of people use their cars to get to work. “Choosing of a mode of transport is rooted in our way of life, and it is not easy to change practices,” said Vincent Kaufmann, director of LASUR.

Their change is often associated with a transition in life. “The greatest opportunities for gains in travelers is by increasing the supply located in the outskirts of large cities on feeder routes to stations, lines, tourist areas – as long as they are well connected to the rail network – or highly frequented lines which can expand the supply in the evening.”

A Planning Tool

This analysis of traffic data is the fifth and final stage of a four-year collaboration conducted between the Transportation Center of EPFL (TraCE) and PostBus. Called Optima and funded with the support of Swiss Post Innovation, this project finishes as an undeniable success for both partners. Scientists have developed analytical tools that are both qualitative and quantitative to determine the factors at work in transportation choices. PostBus profits from valuable input on the determinants that influence demand, an assessment of the impact of its development policies in recent years, and especially ways to sharpen its future strategies.