As far as possible, the statistics have been made comparable between modes of transport and over the years from 1946. Missing
data is estimated. If major changes are made to the statistics due to corrected / changed levels in the base data, the time
series is revised back to achieve the best possible comparability over time.
In the 2012 statistics, the data source for scheduled road transport (buses and coaches) was changed. At the same time, the
figures for 2010 and 2011 were revised for both passengers and passenger-kilometres using the new data source (the public
transport statistics).
Up to and including 1999, the number for the bus could be obtained directly from the bus service statistics. After the bus
service statistics ceased in 2000, the bus service figures in the domestic transport statistics were obtained from the KOSTRA
Transport Module. However, these statistics only cover the subsidized route transport, and an add-on was calculated to compensate
for the lack of coverage in KOSTRA (for the part of the non-subsidized transports that were captured by the previous forms).
This was done until the statistical year 2011. The calculations became uncertain over time.
Towards the end of the 2000s, new statistics were established for, among other things, buses in the public transport statistics.
After a closer assessment, among other things in the Advisory Committee on Transport Statistics, it was decided to replace
the previous data source with the public transport statistics starting from the statistical year 2010. However, this lead
to a downward adjustment in the production figures for the bus sector, as part of the non-scheduled bus transport is no longer
included. In addition, the statistics for transport with buses and coaches in the domestic transport statistics should ideally
include all transport done by buses and coaches, i.e. also the transport operated by coach tour operators (not covered by
the current data sources).
As of the statistical year 2015, the basis for calculating maritime transport figures were changed, both for freight vessels
along the coast (ships transporting for hire or reward and on own account) and for car ferry routes. The statistics for freight
vessels were previously based on projections. However, the basis for the projections became uncertain over time. The figures
for 2014 (tonnes and tonne-kilometres) were not updated with the publication for the statistical year 2014, but were set as
equal to the 2013 figures pending review and update. This work took longer than expected, which delayed the publication of
the statistics for 2015 to January 2017. A new time series for freight vessels was calculated back to 2010. The previous time
series was closed. The car ferry routes were also revised back to 2010 based on new data from the Norwegian Public Roads Administration.
With the publication of the 2016 statistics, the tonnage carried for railway transport and ferry transport was adjusted to
not include the tare weight of vehicles, containers and other transport units (leaving only the weight of the transported
goods with packaging). This was done to ensure the best possible coherence between the weight calculations for the various
modes of transport. The time series for tonnage carried and transport performances for railways and ferries were simultaneously
revised back to 2010.
With the publication of the 2017 statistics, the main data source for the number of passengers and passenger-kilometres for
other regular boat services was changed from the KOSTRA statistics to the public transport statistics. Consequently, the time
series for other regular boat services was revised back to 2007 based on the figures from the public transport statistics.
In addition, the passenger-kilometre figures for Hurtigruten, which is part of the other regular boat services, were adjusted
to reflect changes in the passengers’ average length of travel in recent years.
With the publication of the 2018 statistics, the tonne-kilometre figures for sea transport for hire or reward and own account
for the years 2010-2017 were revised in accordance with changes in the calculation model for distances traveled in domestic
shipping. The tonne-kilometre figures for rail transport in 2016-2017 and the passenger-kilometre figures for other scheduled
services in 2015-2017 were also adjusted as a result of changes in the underlying statistics.
With the publication of the 2019 statistics, the figures for passengers and passenger-kilometres for scheduled bus transport
were adjusted for the years 2015-2018 due to changes in the underlying statistics. The same was the case for the 2018 figure
for tonne-kilometres by rail.
As of the statistical year 2019, figures for passenger transport by train are published together for all railways in Norway,
as the previous distinction between the Norwegian State Railways and other railways is no longer relevant.