Maxis' SimCity has offered traffic simulation, with freeways and surface streets, for the last few versions. The model is very simplified: all streets are two-way and two lanes, while freeways are six lanes (four lanes in SimCity 3000) and elevated throughout, even while traversing the desert or scaling hillsides.
The four-way interchange rendering in SimCity 3000 (see screenshot) was a step up from the SC2000 version, yet still missing a few ramps. The three-way interchange can't be rendered, so SC3000 instead blocks off the roadways with construction barriers.
Diamond interchanges (you can see a ramp at the lower left of the picture) look nearly conventional.
Ramps do provide access in the model (they're not just for show; no ramp, no access) and you can install them individually.
SimCity 4 offers greater interchange detail, with real cloverleaf interchanges, though all freeways were still elevated.
The SC4 Rush Hour expansion pack made SimCity roadgeeking much more fun, adding ground-level freeways, semidirectional T three-way interchanges, and four-lane boulevards.
Some very motivated and smart SC4 users at SimTropolis have created even more interchanges, including stacks and three-way directional Y's.