> There's a few trucks hauling freight

There's a lot of trucks hauling freight. The US has the largest train network in the world, it notoriously handles primarily freight, and still, more than 70% of freight in the US goes by truck.

If these roads are the average urban interstate highways, then about 10%ish of the traffic is heavy truck traffic.

https://www.fhwa.dot.gov/policyinformation/statistics/2020/v...