A signalised junction has no meter, no invoice and no line in any national energy account. It is treated as neutral ground. It is not. It is the single most energy destructive square metre in the built environment, and there are millions of them.
Two variables decide almost everything: how many vehicles pass through, and how fast they were travelling before they were forced to stop. Kinetic energy scales with the square of speed, so the speed zone matters more than most people expect. Entry and exit speeds are held at the zone speed throughout, which understates any junction sited at a speed band boundary.
Every comparison below is set on the basis most generous to the power station. Named facilities are recognisable examples of each technology, not the source of its median. The right hand column is the one that matters: how much land of that technology it takes to generate what this one junction destroys.
The waste is not caused by the cars. It is caused by the geometry. Change the geometry and the loss does not need to be recovered, captured or offset. It never occurs. The same footprint that was destroying energy becomes the lowest cost basis of any compute environment ever engineered, because the land, the grid connection and the public right of way are already there.
At the quietest end of the range modelled here, a 50 km/h junction carrying 6,000 vehicles a day still destroys energy roughly seven times faster per square metre than a nuclear station generates it. There is no realistic signalised junction where this argument fails.
| Speed zone | Energy prevented | MWh/m²/yr | CO₂/yr | Fuel cost | Continuous power |
|---|---|---|---|---|---|
| 50 km/hUrban · canonical | 13.8 GWh | 39.4 | 3,900 t | €2.64M | 1.57 MW |
| 60 km/hNational | 17.8 GWh | 51.0 | 5,000 t | €3.41M | 2.04 MW |
| 80 km/hInterurban | 22.2 GWh | 63.6 | 6,250 t | €4.26M | 2.54 MW |
| 100 km/hDual / motorway | 27.3 GWh | 77.9 | 7,650 t | €5.22M | 3.11 MW |
Fifth Avenue has forty blocks. Macau has one peninsula. The Hoover Dam has one Colorado River. Their value density exists precisely because it cannot be repeated. A junction can be repeated everywhere, because every city already built thousands of them.
1 MW of compute and 4 MWh of storage, on a footprint that already exists.
25 MW of distributed compute and 100 MWh of grid connected storage.
100 nodes over ten years, funded by a single regional raise.
900 nodes. 900 MW of compute. 3.6 GWh of storage. No new land acquired.
A model that only lists the assumptions favouring its own conclusion is marketing. These are the assumptions in both directions, including the ones that weaken the case.
The fuel a junction forces vehicles to burn that a free flow crossing does not: deceleration to rest, idling, and rebuilding both translational and rotational kinetic energy from zero at the engine's least efficient operating point. Blended 9.25 kWh/L, 2.60 kg CO2/L, €1.77/L.
Wheels, drivetrain and engine inertia must also be rebuilt from zero. Applied at 8 to 13 per cent of translational energy by vehicle class, from the standard automotive equivalent mass relation. Applied to acceleration only. Idling has no kinetic component. Estimated, not measured.
All headline figures count only fuel burned at the junction. The upstream energy of extracting, refining and distributing that fuel adds roughly 19 per cent more energy and 0.60 kg CO2e per litre. On a well to wheel basis the canonical figure is 16.4 GWh and 47 MWh/m².
Power density uses the 350 m² the node occupies. The painted crossing that causes the loss is nearer 30 m², which would give a figure roughly ten times higher. The larger, weaker denominator is used deliberately, because it matches how a power station's own footprint is measured.
Brake and tyre particulates, nitrous oxide formed by exhaust aftertreatment, the carbon cost of the urea that modern diesels consume to meet emissions limits, and time lost decelerating and queuing. All real. None included. The figure would be higher with them.
Published global medians from a peer reviewed meta analysis of operating facilities: gas 480 W/m², nuclear 241 W/m², solar 6.6 W/m², onshore wind 1.8 W/m². Hoover Dam calculated from its own output across Lake Mead. Each set on the basis most generous to the comparator.
umpireal is seeking pilot partners, road authority relationships and infrastructure investors. The geometry is filed. The model is published. The junction is already built.