The truck toll mileage index measures the mileage covered by trucks with four or more axles, which are subject to toll charges, on German motorways. As of reference month October, truck toll mileage indices for the Länder have also been available. From now on, the website of the Federal Statistical Office will show the Land indices every month at the same time as the truck toll mileage index for Germany. Unadjusted results as well as calendar and seasonally adjusted results are available both for the Land indices and the truck toll mileage index for Germany1). The Land data are available in table 42191-0010 of the GENESIS-Online database.
The Federal Office for Goods Transport adds up the mileage (kilometres) covered by vehicles subject to toll charges per Land to calculate the monthly truck toll mileage index broken down by Land. That mileage is placed in relation to the average monthly mileage per Land in 2015. Only the mileage covered by trucks with four or more axles on German motorways is included here as in the truck toll mileage index for total Germany. The time series of values regarding the regional mileage index by Land starts in January 2008. For the all-German truck toll mileage index, values are available as of January 2005. The mileage index is based on a nearly complete coverage of all journeys subject to toll charges performed by trucks with four or more axles on motorways in Germany or the relevant Länder.
Connection between regional truck mileage and regional industrial activity
Economic activity generates and requires transport services – there is therefore a close connection between the economic development and traffic by trucks. Due to its early availability, the all-German truck toll mileage index is used as an additional short-term economic indicator2). A first explorative analysis shown below outlines the connection between truck mileage and industrial activity at the regional level of Länder.
The correlation of calendar and seasonally adjusted month-on-month change rates is used to measure the connection between the truck toll mileage index and turnover development in manufacturing3). The closer the correlation coefficient is to zero, the weaker is the connection between the variables. In turn, a correlation coefficient of 1 indicates a perfect connection between the variables. Figure 1 show the correlation coefficients between the month-on-month change rates of the regional truck toll mileage indices and the regional turnover development in manufacturing for all Länder. The analysis refers to monthly seasonally adjusted month-on-month change rates for the period from February 2009 to July 2021.
Figure 1
The correlation coefficients are between 0.75 for Bayern and 0.12 for Schleswig-Holstein. The figure illustrates that differences in the quality of the connection between regional truck mileage and regional industrial activity should be taken into account.
For the top nine Länder in Figure 1, the correlation coefficient is higher than 0.5, which suggests a rather close connection between regional mileage and regional turnover. These Länder tend to have industrial structures with a focus on sectors that create much truck traffic. Examples are the production of motor vehicles, trailers and semi-trailers and fabricated metal products and, in some Länder, of machinery and equipment.
Non-city Länder with a correlation coefficient of under 0.5 are Brandenburg, Sachsen-Anhalt, Mecklenburg-Vorpommern and Schleswig-Holstein. The industrial structure in these Länder differs from that in the Länder mentioned above. The production of food products, for example, is more important here. Also, the proportion of manufacturing, that causes much freight traffic, of gross value added is below the national average in these four Länder.
The city states of Berlin, Bremen and Hamburg have very low correlation coefficients (under 0.3). Overall, there is less truck traffic in the city states and, in addition, the economic structures there differ considerably from that in non-city Länder. For instance, the proportion of business services, which cause less traffic, of regional gross value added in the city states is higher than the national average.
Connection between regional truck mileage and all-German industrial activity
Due to the importance of transit traffic in the Länder and of the arrivals in / departures from Länder, it is useful to also examine the correlation between regional truck mileage and all-German turnover in manufacturing. Figure 2 shows the relevant correlation coefficients. For most Länder, they are higher than those in Figure 1, while for Nordrhein-Westfalen the correlation is roughly the same.
Figure 2:
In Brandenburg and Sachsen-Anhalt, there are structural differences in the results when we compare the correlation between regional truck mileage and all-German turnover development. Here, there is a more marked connection between the truck toll mileage index and the turnover index in manufacturing for total Germany, which is not observed in a purely regional examination. West-east transit traffic seems to play an important role here.
Conclusion
The truck toll mileage index reflects very exactly the development of regional truck mileage as it is based on an almost complete coverage of all journeys subject to toll charges performed by trucks with four or more axles on German motorways. It is however not suited in all Länder as a rough indicator of regional short-term economic development. A first explorative correlation analyses has shown a relatively close connection between regional truck traffic and regional industrial activity for many non-city Länder. In the city states as well as in Brandenburg, Sachsen-Anhalt, Mecklenburg-Vorpommern and Schleswig-Holstein, that connection has hardly been observed at all. However, the index can be used in these Länder, too, to show and analyse traffic effects.
Footnotes:
1):: Cf. "Digital process data from truck toll collection as new building block of official short-term statistics (only in german)". Since the coronavirus crisis, additional experimental daily data have been released, which are updated every week ("Daily truck toll mileage index based on digital process data from toll collection system (only in german)").
2):: Short-term statistics generally focus more on the development of results over time than on the absolute values of individual reference months. For this reason, publications on short-term indicators primarily present rates of change on the previous month. Often, such change rates are considerably affected by seasonal effects. This is why short-term indicators are generally subjected to seasonal adjustment, which may include calendar adjustment.
3):: For the purpose of this analysis, regional turnover development in the Länder was once subjected to seasonal adjustment. Non-seasonally adjusted turnover in manufacturing is available for Länder in the GENESIS-Online database in table 42111-0031.