How many want to drive the bus? Analyzing the number of bids for public transport bus contracts

This paper examines how different factors related to contract characteristics and the operational and tender environments affect the number of unique bidders placing bids in tenders for bus contracts. A generalized Poisson model is used with a comprehensive data set containing most of the recently tendered bus contracts in Sweden, spanning the period 2007–2015. The main finding from the analysis is that most contract characteristics change participation in tenders by approximately 0.1–0.5 bidders. Operator-restricting measures such as special requirements on buses have a similar limited effect. Further, the number of tenders that are open at the same time as a specific tender was shown to reduce participation by almost two bidders. Finally, there is evidence that the local competitive environment is of importance, and the public transport authorities therefore need to be concerned with entry barriers in their tenders