[philipw]

An air gap is hardly a solution for traffic information the route planner HAS to talk to the computer responsible for getting from A to B. In the same way that firewalls are no longer particularly relevant, air gaps appear to be flawed now too, the only way to solve any security issue is better code quality..

[leereeves]

It's not perfect, but an air gap can help reduce the attack surface and interval.

Better code quality is important too, of course.

I agree with cameldrv that it's going to be a challenge.