The road network is the backbone of any GTA map. Trailer 2 has enough driving frames to let us map out the highway infrastructure - or at least the parts that are shown.
We map the highways we can see onto their plausible real-Florida counterparts. Refer to the driving routes piece for particular routes.
The highways visible in trailer footage
An interstate-style highway running along the coast (the I-95 analogue). A highway running south across the bridge route into the Keys (the US-1 analogue). An inland highway cutting through the wetlands (the Tamiami Trail analogue). Suburban arterial roads that connect Vice City to the inland suburbs (corresponding with real-Miami routes like the Palmetto Expressway).
Multi-lane suburban arterials, secondary state routes through the rural towns, and county-grade roads through orange groves and farmland complete the visible network.
What these analogues do and don't tell us
They give us the general layout - a coastal interstate, a north-south spine through the Keys, an inland east-west route, connecting feeder roads. But they don't give us exact route numbers, named exits or mileage.
Rockstar commonly renames and re-routes actual highways. The visible network appears Florida-shaped, not Florida-sized. Use the analogues as a guideline, not your GPS.
Traversal implications
If the highway network roughly corresponds to Florida's geography, drives across the state feel natural. You can take the bridge route to the Keys, the coastal interstate north through the suburbs, or the inland route through the swamps. A drive all the way across the map is plausibly long enough to feel like an actual road trip without being too tiresome.
Compression applies, of course. See the map size piece, where we discuss the size question separately.