Regularity-based bus services Stockholm

The scene is familiar: Rush hour in the big city, we stand and stomp at the stop in anticipation of the bus. Once it arrives, it is packed with passengers. Shortly after, an empty bus arrives. Transport researchers at KTH together with Stockholm Region Transport Administration (SL) and the operator Keolis, have found a solution for this inefficient clustering of buses and the costly waiting time for society.

In two successful field trials, a hundred bus drivers in the inner city of Stockholm were trying to set the timetable aside and instead run based on the time headway, the frequency, between the buses. The trials were done on trunk lines, blue buses with high frequency, on bus line 1 in autumn 2011 and on lines 1 and 2 in 2012. Via a computer screen in the buses, the drivers received information on how they were positioned in relation to the bus ahead and could speed up or slow down to correct the flow.

The research on bus regularity and field trials on bus lines 1 and 3 has been financed by Vinnova and Stockholm city respectively, in a collaboration between the Division of Traffic and Logistics and the Center for Traffic Research (CTR) at KTH, the Traffic Supply Unit at SL and Keolis. The transport research environment Transport Strategic Research Funding (Trenop) at KTH has been important support in the research.

Significance of impact case

According to calculations by the Traffic Analysis Authority, the annual cost of delays in public transport in Stockholm County is 5.98 billion SEK. The new way of driving high-frequency bus lines makes an important contribution to reducing these high costs. The pilot study led to a more even distance between the buses and fewer fully-loaded buses. The drivers became less stressed and the time that passengers had to wait for the bus every day was cut by ten percent. In SEK, this can be estimated at 2.2 million in reduced social costs in one month. The regularity-based strategy is now included in the long-term contracts that SL has with its operators and discussions are in progress. The pilot studies have thus had a long-term effect on how bus traffic looks in the inner city of Stockholm.

Reach of impact case

The long term beneficiaries of the impact are the residents of Stockholm, or of any other major city throughout the world. The intermediate beneficiaries are:

  • Stockholm Region Transport Administration (SL) as public transport authority
  • City of Stockholm and surrounding municipalities as owners of urban street space
  • National Transport Administration (Trafikverket)
  • Keolis as bus operator
  • Consultancy companies as performers of follow-up evaluations


The following individuals can be contacted to provide testimonals:

  • Azhar Al-Mudhaffar , Trafikförvaltningen Region Stockholm, on pilot studies.
  • Siri Brolén , Trafikförvaltningen Region Stockholm, on current work on bus regularity.
  • Karl Orton , Keolis Sverige, on pilot studies. The following popular science, and general press coverage, popular articles, interviews, etc. may be noted:

Impact creating activities

The first pilot project was conducted for bus line 1 in 2011 (RETT2). Focus was on regularity, decentralization and traffic management. In 2012, the field work was expanded to line 1 and 3 (RETT3). Focus on pure trunk line services, systems, proactive traffic management. In 2014 the strategy was introduced on line 4 together with Stockholm city (RETT4). Other measures included boarding in multiple doors and street im- provements. Work has continued subsequently to further improve the speed of the inner city bus lines as well as other trunk lines.

Underlying research/education activities

The bus project builds on previous close collaboration between KTH and SL in various projects and degree projects. It started with a simulation model that the researchers at KTH have developed, BussMezzo, where data from SL and Keolis were used on line 1, and then dealt a great deal with communication between all parties involved. Not least, much time was spent on informing and engaging the bus drivers.

The bus industry is traditionally very conservative. It costs to try new things and also deals with road safety. The fact that one could test different strategies in a safe environment in a simulation model before was crucial for SL’s positive attitude to trying the method in the field.