Tram or Bus; Does the Tram Bonus Exist?
Tim Bunschoten, Goudappel Coffeng BV, Eric Molin, Delft University Of Technology, Rob Van Nes, Delft University Of Technology
The tram bonus is examined by comparing the alternative specific utility attached to tram and a bus while controlling for both travel attributes and perceived differences between both vehicle types.
The tram bonus is a much discussed topic as there is severe uncertainty about its definition and its existence. In this paper the tram bonus is considered to be the extra value it generates for travellers, which causes a new tram service to gain more passengers when compared to an equivalent bus service. The tram bonus is examined by comparing the alternative specific utility attached to tram and a bus while controlling for both travel attributes and perceived differences between both vehicle types.
To examine the alternative specific utility, a stated choice experiment is conducted. Respondents make a series of choices between a tram and a bus alternative, which are both described in the same attributes and levels. These attributes involve access travel time, frequency, in vehicle travel time, transfer time, and egress travel time. As in this way the level of service is the same for both alternatives, the alternative specific utility captures the additional value that is attached to tram compared to bus.
In addition, it is examined to what extent the alternative specific constant is influenced by perceived differences between bus and tram. To that effect, respondents responded to a list of 26 statements about characteristics related to driving, reliability, the vehicle, recognisability, and environmental friendliness. Respondents were requested to what extent they felt each of these characteristics belonged to either only tram or only bus, or some mixture of both (hence, a five point rating scale was used). Factor analysis was applied to construct common factors. These factors are added to the utility function.
If only the service level variables are included in the utility function, the alternative specific utility of the tram is, as expected, positive and statistically significant, This suggests that the tram bonus exists. If the perception factors are added to the utility function, the alternative specific constant becomes statistically insignificant, suggesting that extra utility of trams can be explained by these perceptions factors. The perception factors atmosphere in the vehicle, characteristics of the vehicles and the displaying of travel information were found to be statistically significant.
Further analysis indicated that the tram is preferred over bus in the three major tram cities in the Netherlands (Amsterdam, Rotterdam and The Hague) but that the extent of these preference difference varies among these citys, whereas in the cities without a tram the bus is preferred. This suggests that the intrinsic value attached to tram is influenced by being familiar with the tram and even depends on the specific tram system. In addition, it was found that travellers that nearly ever use public transport have a preference for bus, while travellers that weekly use public transport have a preference for tram. Furthermore, cyclists and tram passengers have a clear preference for tram, on the other hand car drivers and bus passengers have a preference for bus.
Finally, an analysis is made of the impact of the intrinsic value of the tram on the passenger number growth. This is examined by using different elasticities. This paper ends with a discussion of the implications of the results for transport planners.
Association for European Transport