A key task in pricing and taxation is to estimate the various components of social marginal costs (infrastructure,congestion, air pollution, global warming, and accidents) as a basis for efficient charging for infrastructure use.
Although several EU-funded studies have been conducted in past decade, there is a need for further econometric and
engineering-based studies on the relationship between infrastructure damage and traffic volumes to provide more evidence on the less researched types of infrastructure.
Allocation of infrastructure costs to vehicle type is important for EU policy, given the charging schemes for heavy goods vehicles (HGV) in several countries and the vignette systems for private vehicles.
An important input parameter in allocating infrastructure costs to types of vehicles is the fourth power rule. This rule, which suggests that damage
to the road surface increases with the fourth power of the axle load, stems from experiments done in the USA in the 1960s.
Further research and guidance would also be helpful in allocating costs in rail infrastructure charging and regulation.
The rule of operating costs in estimating marginal infrastructure costs has to be analysed in the less researched modes of terminal infrastructure in waterborne and airborne transport.
Furthermore, the link between port dues and marginal costs (in general, not only restricted to infrastructure costs) is also an open issue.