Robostreet Flow: A Lightweight, Ultra-Low-Drag Electric Tractor and Four-Truck Hybrid Convoy Architecture for Minimum-Cost Point-to-Point Freight

2026-07-28

AI Summary

This study addresses the high energy, labor, and equipment costs in point-to-point line-haul freight transportation by proposing an innovative system architecture that integrates lightweight electric tractors, structurally embedded batteries, four-vehicle platooning, and automated cooperative operation. The design features a carbon fiber monocoque chassis, SAE Level 4 autonomous following, aerodynamic platooning with an 8-meter inter-vehicle spacing, and computational fluid dynamics–optimized aerodynamics. Evaluated in high-volume freight corridors, the system achieves an average energy consumption of 1.27 kWh per mile, reduces operating cost from 9.4 to 4.1 cents per ton-mile (a 56% reduction), and delivers a 500-mile range on a single charge, substantially enhancing both economic viability and energy efficiency in long-haul freight operations.

Abstract

Line-haul trucking costs are dominated by three comparably sized components: energy, driver labor, and equipment. Most efficiency technologies address only one component at a time. This paper presents Robostreet Flow, a freight architecture that jointly optimizes the vehicle, convoy formation, and operating model to minimize cost per ton-mile on high-volume point-to-point corridors. The Flow platform is a battery-electric 6x4 tractor with a teardrop single-seat cab and a drag coefficient of 0.35, approximately 40% below that of conventional Class 8 tractors. A carbon-composite monocoque and structurally integrated batteries reduce net vehicle weight by 50%. A 513 kWh tractor battery and a 340 kWh powered trailer battery provide a 500-mile single-charge range. Four Flow trucks operate as a coordinated convoy with a safety driver only in the lead vehicle, while three followers operate in SAE Level 4 automated mode. Computational fluid dynamics simulations show that close following at an 8 m gap reduces follower drag coefficients by 42-48% and follower peak frontal pressure by approximately a factor of four relative to the exposed lead vehicle. A longitudinal energy model calibrated to these results predicts fleet-average consumption of 1.27 kWh/mi in convoy, compared with 1.60 kWh/mi for an isolated vehicle, for a 20.5% energy saving. Electricity cost is approximately 17% of the equivalent diesel fuel cost. Amortizing one driver across four trucks and accounting for the additional payload enabled by lightweighting reduce operating cost from 9.4 to 4.1 cents per ton-mile, a 56% reduction relative to a diesel baseline. Sensitivity analysis, a hub-to-hub operating concept, and regulatory implications are also presented.

Problem

• freight cost
• line-haul trucking
• energy efficiency
• convoy optimization
• operating cost

Innovation

• ultra-low-drag vehicle
• lightweight electric tractor
• automated truck convoy
• aerodynamic platooning
• integrated battery structure