Modal equity — pricing the road, fairly

The federal gas tax (18.4¢/gallon) hasn't increased since 1993 — half its inflation-adjusted value gone. As the fleet electrifies, the tax base shrinks faster: an EV driver pays nothing for the road. By 2035, when new car sales are projected majority-electric, the Highway Trust Fund is structurally insolvent without General Fund transfer. The gas tax already covers less than 30% of road costs; the remainder is paid by general taxation — meaning transit riders, cyclists, and pedestrians cross-subsidize drivers.

The Accord retires the gas tax over five years and replaces it with a Vehicle Mileage Fee (VMF) for light vehicles and a weight × speed × congestion fee for heavy commercial vehicles. Per-mile, calibrated to actual road damage. Revenue-stable as the fleet electrifies.

Pavement damage scales with the fourth power of axle load and compounds with speed via dynamic loading (impact forces multiply repeated stress on pavement). A fully loaded 80,000-lb semi causes roughly 9,600× the marginal pavement cost of a 3,500-lb sedan, per the FHWA Highway Cost Allocation Study. Today the truck pays 4–5× the sedan rate. The ratio of damage caused to fees paid is so far off that state DOTs and general taxpayers absorb the gap — and the under-pricing distorts freight modal choice toward road over rail and intermodal where the damage profile is far smaller per ton-mile.

Combined damage: Damage ∝ Weight⁴ × Speed^1.5. Static loading from weight; dynamic loading from speed. Pricing the truck for both at once is the engineering-correct rule. The Accord uses Weight^3.5(a transition exponent that becomes 4.0 once rail capacity expands).

The fee itself is the policy instrument — no ring-fenced trust required. The rate is sized to do two things at once: approximately recover the damage cost (so heavy trucks pay for the pavement they wear) AND shift behavior toward saving pavement (lighter loads, slower speeds, modal shift to rail). Revenue routes to the General Fund alongside other federal receipts; the calibration of weight, speed, and congestion exponents does the architectural work. Earmarking would add ceremony without adding effect.

The fee defaults to maximum registered weight and maximum legal speed. Accurate, tamper-evident monitoring reduces the fee. The burden is on the operator to prove lower impact, not on the state to prove higher impact. No working monitor? Pay maximum. Tampered monitor? Pay maximum. Working monitor with verified data? Pay actual.

The fee structure self-enforces. A 60K-lb truck at 55 mph with valid monitoring pays $9,300/yr; the same truck with failed monitors defaults to $79,000/yr — a 6.5× penalty for not maintaining equipment. No inspection regime required; the fee structure does the work.

Congestion premium applies only inside designated congestion zones AND during peak hours — both conditions required. A truck in rural Wyoming at 8am pays no premium (wrong location). A truck inside Chicago metro at 11pm pays no premium (right location, off-peak). A truck entering the Chicago metro during rush hour pays the full premium (both conditions satisfied). Zones are defined by population density, road density, and observed delay; peak hours are statutorily-set windows (typically 6–9am and 4–8pm, weekday). Heavy vehicles carry a 2× congestion multiplier (one truck displaces ~2 cars in flow capacity).

Detection rides on the same GPS/telematics infrastructure already required for ELD compliance — no new device mandate. Trucks with valid monitoring pay accurate billing; trucks without pay the default 30% peak-exposure factor. Privacy by architecture: zone-entry detection (knows you entered the zone, not your route within); no data retention beyond the billing period; opt-out at the maximum-rate premium.

Drivers today receive a larger per-passenger-mile public subsidy than transit riders, once full social cost is counted (congestion, crash, emissions, parking land, road wear). The Accord names this and corrects it. 100% of the urban congestion premium flows to regional transit operating subsidy. The result is a virtuous cycle: congestion fees rise → transit funding rises → transit improves → ridership shifts → driving falls → congestion eases → remaining drivers benefit from faster roads.

Statutory rule: federal transit operating assistance per passenger-mile shall not be less than the per-passenger-mile public subsidy implied by unpriced road access. Congestion fee revenue is allocated to achieve that parity.

The fee structure produces a powerful unintended effect. A human driver under hours-of-service limits manages ~170,000 mi/yr at typical loads; an autonomous truck running 22 hours/day at 55 mph manages ~440,000 mi/yr. With weight^3.5, splitting one 100K-lb load into two 50K-lb runs cuts fees by ~80% and is cheaper than overloading once driver cost is zero.

What emerges: continuous, light, slow, congestion-avoiding autonomous trucks operating ~24/7. They depart off-peak, stage outside metros during rush hour, deliver in the midday window, and pay base rate everywhere. One autonomous truck displaces 2.5 human-driven trucks in annual capacity while paying ~18% of the fees per mile. The fee structure does the steering; the freight operators do the optimizing; rail picks up the long-haul corridors where it always had the comparative advantage.

The Parity Rule: no mode receives a larger public subsidy per passenger-mile or per ton-mile than another. This is not subsidy-equalization to zero — public benefit varies by mode (rural connectivity, freight rail, transit social return). It is explicit, transparent allocation, replacing today's hidden cross-subsidies with visible cost-recovery ratios.

The combined fee architecture funds the full state-of-good-repair program without General Fund expansion. Roads and bridges from user fees; transit from congestion-premium parity plus modest General Fund contribution; intercity rail, airports, and waterways from sector-specific fees plus the General Fund share that reflects their broader public benefit (national connectivity, defense mobility, flood control co-benefit).

High-speed rail does not fit inside the state-of-good-repair envelope. A single corridor (NEC, California, Texas Triangle) costs $100B+; the network costs an order of magnitude more. The Accord names HSR as a longer-horizon adaptation play funded from the Climate Adaptation Trust in the Engine-6 Trust's back-end, not from VMF receipts. The premise: as the carbon fee escalates ($80 → $680/ton), short-haul aviation prices in its full carbon cost, and HSR becomes the clean replacement on corridors under ~500 miles. The Accord does not commit to a specific HSR build today; it preserves the architectural option for a future Congress to fund it from the Trust's accumulated reserve when the corridor economics clear.