The core
The momentum tax: ~$5 trillion a year
The momentum tax is the direct cost of forcing vehicles to stop and start: fuel burned twice, time lost in queues, and the extra wear on engines, brakes and tyres. Modelled across the world’s signalised junctions, it comes to roughly $5 trillion a year.
~5,000 TWhEnergy lost every year to stopping, slowing and restarting
~75bn hrsOf human time lost, about nine hours for every person on earth
~1.3 GtCO₂ a year, roughly 3 to 4% of global fossil emissions
Beyond the core
The wider system cost
| Wider cost | Who pays |
|---|---|
| Crash costs at junctions: medical, legal and lost output | Health systems, insurers, families |
| Air pollution health costs | Health systems |
| Freight delays and penalties | Logistics and retail |
| Building and maintaining signals | Taxpayers |
| Noise, stress and mental health | Society |
| Carbon costs | Nations and companies |
| Total system cost, including the momentum tax | An estimated $6–7 trillion a year |
Insurance premiums are how much of the crash cost is paid, so they are not added again on top. All figures are modelled estimates.
In context
What the numbers mean
~4.5%Of global GDP, about $110 trillion in 2024, taken by the momentum tax alone
600+Large nuclear reactors’ worth of annual output, lost at junctions
~1.3 GtCO₂ from one solvable cause
This is not a marginal inefficiency or a technical edge case. Stop-go infrastructure is one of the largest single sources of economic waste in the modern world, and it has never been tackled at the infrastructure level, because until now there has been no way to pay for the fix.
The question is not whether we can afford to change this. It is how we have accepted the cost for so long.