Article assumes that the hyperloop can/would follow existing highways. Considering the cost of diverting traffic during construction, it seems unlikely you could build it for anything close to the advertised $6 billion while following existing highways.
Also, the structure would need to be tall (or short) enough to bypass highway bridges and overpasses...
The paper also included a map that showed the route running between Hayward and Burbank, not city centers. That may be how Musk proposes to solve the curve radius problem.
Also, the structure would need to be tall (or short) enough to bypass highway bridges and overpasses...