You could do this by decreasing the efficiency of the non-freeway roads, or increasing the cost of using the roads, which both only ‘solve’ the problem by reducing general quality of life (especially for poorer people, who might just get even poorer if they can’t commute affordably).
Or you can increase road capacity to keep up with population growth, and invest in alternative transport that people actually want to use. That means no cycle lanes or buses, because people really don’t want to use them (buses are only really efficient for short trips, if you have to change buses to get to work then it ends up taking so long you may as well just be inefficiently sitting in the comfort of your own car).
This doesn't work because in a city you'll eventually you end up with more roads and parking lots than buildings. US cities were built like this, and the more road capacity you build, the more sprawl you get (everything is further apart), which increases how much people have to drive which increases the traffic... It's an evil spiral of congestion.
I'd hesitate to specify that certain equilibria are reasonable while others are not. Building more roads to reduce congestion does not achieve that goal, in part because of the latent demand you describe (see [0] "Effect in transportation systems").
Ultimately, if your goal is to decrease time spent traveling, you will see more benefit from alternative policies. Such policies may include:
* increasing cost of using the roads (e.g. congestion pricing)
* constructing alternate, denser forms of public infrastructure (e.g. subways)
* increasing the density of passengers in vehicles (buses, carpooling, etc.)
* funding technological advances that increase the density of vehicles utilizing the road (e.g. self driving cars)
[0] https://en.wikipedia.org/wiki/Induced_demand