The costs of building and maintaining streets are only part of what motor traffic costs. A larger share falls outside any budget: on health, on the environment, and on people who live alongside traffic without necessarily taking part in it.
Different kinds of cost can be distinguished. Some are well measured, others are hard to put a figure on. That does not make them small. Each one is listed here, so that none disappears simply because it has no euro value.
health and physical danger
Collisions
Speed and vehicle mass together determine how much energy is released in a collision, and kinetic energy rises with the square of speed. Urban streets therefore carry a permanent physical hazard that falls most heavily on people walking and cycling.
In most European studies, collisions are the largest single cost of road transport, and worldwide they make up more than half of all social costs of car use. They include medical treatment and rehabilitation, lost economic output, administrative and legal costs, property damage and, by far the largest part, the value people place on avoiding death and serious injury. To this must be added what no valuation captures well: bereavement, lifelong disability, and the long-term trauma of drivers involved in a fatal collision.
Who bears it: victims and their families first, then health systems, employers and insurers.
How it is measured: casualties by severity, valued with national values for a statistical life and for injuries.
In the vehicle rating: safety for people walking and cycling, mass and speed capability, and direct vision.
Air pollution
Nitrogen oxides, fine particulate matter (PM2,5 and PM10) and ozone precursors cause respiratory and cardiovascular disease, reduce life expectancy and restrict daily activity. They also cause crop losses, damage to materials and buildings, and harm to ecosystems.
Who bears it: especially people living and working along traffic routes, disproportionately lower-income households, and health systems.
How it is measured: emission factors by vehicle class and Euro standard, dispersion, exposed population and dose–response relationships, valued per tonne emitted or per person exposed.
Tyre and brake wear, and microplastics
Tyre wear, brake wear and road surface abrasion behave differently from exhaust in every way that matters:
- they rise with vehicle mass, regardless of powertrain;
- the tire wear is not reduced by electrification, and heavier electric vehicles make the tire wear worse;
- they are already a major share of urban traffic particulates, and that share is rising as exhaust emissions fall (OECD 2020, Non-exhaust Particulate Emissions from Road Transport: An Ignored Environmental Policy Challenge);
- tyre abrasion is among the largest single sources of microplastics in urban soils, drainage systems and water bodies.
Noise
Traffic noise causes annoyance, sleep disturbance and, with long exposure, cardiovascular disease (WHO Regional Office for Europe 2018, Environmental Noise Guidelines for the European Region). It is the effect most often underestimated, because it acts continuously and at night. It also lowers property values along noisy streets, which shapes who can afford to live where.
Noise rises sharply with speed and is much worse at night. At urban speeds it comes mostly from tyres on the road surface, not from the engine. That is why electric vehicles reduce noise far less in cities than often assumed, and why the vehicle rating applies a night-time multiplier.
environment and climate
Climate
Motor traffic remains one of the largest sources of greenhouse gas emissions in Europe, and one of the slowest sectors to reduce them. The cost includes emissions from driving, from producing and distributing the energy, and from manufacturing and disposing of the vehicle, including battery supply chains.
How it is measured: emissions by mode and energy source, valued either by what it costs to avoid them or by the damage they cause. The choice between the two changes the result substantially and must always be stated.
Land sealing, water and urban heat
Sealed road and parking surfaces prevent groundwater recharge, overload stormwater systems in heavy rain, increase the risk of flash flooding and destroy living soil. Asphalt absorbs heat during the day and releases it at night. It raises urban temperatures and contributes to deaths during heatwaves, mainly among older people and those with pre-existing conditions.
How it is measured: sealed area attributable to traffic, the avoided cost of stormwater capacity, and heat-related deaths attributable to the urban heat island.
These costs are borne mostly locally, by the city and its residents, which makes them the most directly relevant to a municipal charge.
Nature and habitat
Road networks cut through ecosystems and wildlife corridors, kill wildlife and reduce biodiversity. They also enable car-dependent development that consumes farmland and natural land.
Dispersed development carries a further cost that rarely appears in transport accounts: providing public services across a wider area. For the emergency services this cost rises steeply, because keeping response times within a given limit needs more stations, vehicles and staff per resident, and beyond a certain point is not achievable at reasonable cost at all. Outside urban centres, longer response times are accepted in practice, and residents have to rely on themselves for longer until help arrives. Car-dependent dispersal shifts part of the cost of emergency preparedness from the public system onto the people who live furthest from it.
society
Environmental injustice
Air pollution, noise and collision risk fall disproportionately on lower-income households living along main roads, while wealthier households are more likely to live on quieter, greener, traffic-calmed streets. In many European cities, the households most exposed to traffic are also the least likely to own a car. So the question of fairness has two sides: who would pay a charge, and who bears the cost today without one.
Low-income households on the outskirts. Rising rents push many lower-income households out of the inner city to areas with poor public transport. They face long commutes and often depend on a car, while those who can afford central locations have short distances, more time, and the option to walk or cycle. Dispersed development and car dependence reinforce each other. For a charge on car use, this group is the hardest case. That is why relief is tied to whether a real alternative exists, and why good access to public transport is part of the design, not only the price.
Children’s freedom to move
Traffic danger is the most common reason parents give for not letting children move around on their own. The result is a loss of free outdoor play and of the everyday independence that supports physical and social development. Automated door-to-door services offer a way around the problem while leaving its cause untouched.
Divided neighbourhoods
Busy, multi-lane roads act as physical and psychological barriers. They reduce contact between neighbours, suppress street life and increase isolation, above all for older people and people with limited mobility. This cost is poorly measured, which is not the same as small. It is one of the most serious effects of car-dominated streets and one of the least represented in cost accounts, precisely because it resists a euro figure. It is listed here with its measurement gap stated openly. Measuring it is one of the research contributions of this project.
suppressed active mobility
Poor allocation of space and dangerous conditions discourage walking and cycling, which in turn reinforces car dependence. The fewer people walk and cycle, the weaker the case for investing in the conditions that would let them.
economy and geopolitics
Congestion
Congestion costs time, delays freight and energy. It is the one cost that falls mainly on road users themselves, imposed on each other rather than on third parties. That makes it contestable as part of a charge justified by harm to others. Where it is included, it is shown separately and counted only as the additional delay each vehicle causes to others.
Raw materials and end of life
Vehicle production consumes large quantities of steel, aluminium, copper, critical raw materials and energy, and the burden grows with vehicle size and mass. Vehicles, tyres and batteries that are not recovered at end of life become persistent waste. These costs fall mostly outside the city, often outside Europe, which is a reason to name them, not to leave them out.
Energy security
Dependence on imported oil, and increasingly on a few suppliers of battery raw materials, creates supply risks, price volatility and public spending on securing supply, well beyond transport. This is the hardest cost to assign per kilometre. It is described here without a figure, because any figure would be invented.
| cost | already paid? | through |
|---|---|---|
| building and maintaining streets | partly | vehicle and energy taxes, tolls; but not earmarked and not local |
| road damage | partly, for heavy lorries | distance-based truck tolls where they exist |
| space | almost not at all | parking charges, where there are any |
| collisions | partly | insurance covers the financial part, not the human loss |
| air pollution | partly | emission standards, low emission zones |
| tyre and brake wear | no | — |
| noise | barely | limit values, not priced |
| climate | partly | energy taxes, CO₂ pricing |
| land sealing, water, heat | no | — |
| nature and habitat | no | — |
| divided neighbourhoods | no | — |
| congestion | rarely | congestion charges in a few cities |
| raw materials and end of life | partly | producer responsibility schemes |
| energy security | no | — |
| emergency access | no | required by building and fire regulations, but not priced and rarely enforced against parking |
The pattern is the point: what is already priced is mostly what is easy to measure. What is not priced mostly falls on people who are not part of the transaction.
what the charge prices, and what it does not
A charge that claimed to cover every cost would be neither credible nor workable. It acts in three ways, and it leaves some costs to other policies.
| cost | how the charge acts on it |
|---|---|
| collisions | rated: safety for people walking and cycling, mass and speed capability, direct vision |
| air pollution | rated: exhaust emissions |
| tyre and brake wear, microplastics | rated: wear emissions and mass |
| noise | rated: noise emissions, with a night-time multiplier |
| climate | rated: powertrain and emissions |
| space | rated: vehicle footprint; priced through kerb use |
| land sealing and urban heat | through the revenue; indirectly through the price of space |
| divided neighbourhoods, children’s mobility | priced through use: sensitive zones and school streets; through the revenue |
| congestion | priced through use: demand by place and time |
| emergency access | conditions for access; reserved space that parking may not take |
| nature and habitat | not priced; a matter for network planning |
| raw materials and end of life | only partly, through mass |
| energy security | not priced |
The last three rows are deliberate limits. Whether any of them should become part of the charge, and how to avoid counting twice where one feature such as mass stands for several costs at once, is still to be evaluated.
how the costs are calculated
| source | what it provides | used for |
|---|---|---|
| CE Delft, Handbook on the External Costs of Transport, for the European Commission | the European reference: methods and figures across modes and countries | road damage, collisions, air pollution, noise, climate, habitat, congestion, energy supply; the European baseline |
| German Environment Agency (UBA), Methodenkonvention zur Ermittlung von Umweltkosten | monetary values per unit of emission and per person exposed | air pollution, tyre and brake wear, noise, climate |
| TU Dresden (Becker, U. et al.), External Costs of Transport in Germany | external costs compared across car, public transport, cycling and walking | cross-check of the total; comparison between modes |
| Agora Verkehrswende, Municipal Cost Accounting for Mobility | the city balance sheet: which costs actually land in a city budget | streets, space, land sealing and heat; the parking method |
| University of Kassel (Sommer, C. et al.), NRVP 2020 tool | cost comparison per trip between modes | the Munich figures |
| COPERT (European Environment Agency) and HBEFA | real-world emission factors by vehicle type and emission standard | air pollution, climate; the common emission scale in the vehicle rating |