A routing API will happily hand a truck the fastest line between two points. What it usually won't tell you is that the line runs under a 4.0 m overpass with a 4.2 m load on the trailer, crosses an at-grade rail line you're legally required to stop at with placarded hazmat, or threads a county road that's posted closed for construction this week. Flow APIs — HERE, TomTom, INRIX — are excellent at speed : where traffic is moving, how long the trip takes. That's congestion data. It is not infrastructure data. The overpass height, the bridge weight rating, the truck-restricted segment, the rail crossing, the active work zone — those live in 57 different state and provincial 511 systems, and a flow API doesn't read them. That gap is what Road511's routing endpoint closes.…