Why the Huge Difference?

1. Live Load (Weight Carried):

• Freeway Bridge: Must support fully loaded semi-trucks (80,000+ lbs) moving at high speeds. The "dynamic load" (bouncing/braking) adds massive stress.

• Autonomous Freeway Bridge: Could only need to support passenger cars (~4,000 lbs) moving even faster.

• A structure for 80,000-pound vehicles at 60 mph requires significantly more concrete and steel—often 10 times more—than a structure designed for 4,000-pound vehicles at 120 mph.

2. Deck Thickness:

• Freeway Bridge: The concrete deck is typically 8-10 inches thick and heavily reinforced with rebar to survive weather, salt, and millions of load cycles.

• Autonomous Freeway Bridge: zero harmful emissions means autonomous freeways could be covered to protect from the elements

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3. Labor Costs:

• One tenth the concrete and steel means one tenth of the labor costs and emissions, from mining to smelting, from shipping to construction

 

Bonus: Underpass

• Freeway Bridge: Combination of large structural elements and noise prevents other commercial uses above or below from being desirable or affordable

• Autonomous Freeway Bridge: Could create quiet and spacious enough places for parking and other commercial structures to use the space underneath