Working inside or outside "the system" in lowering CO2 emissions?

I'm new here and am reflecting on what work of mine would be most effective in reducing co2 emissions. Hopefully my questions could also span broader discussions about this topic. 

 I'm working as a traffic planer for a consultant company. Traffic is a huge source of emissions in my country and so decreasing car traffic in favor walking, biking and public transport can have a huge impact. However I don't feel like I'm making much impact in the field. I can make suggestions in the projects I'm part of but in the end the customer decides the level of ambition and in extension politicians, since our customers are mainly municipalities or the state transport administration. The bottle neck for traffic planing is not a lack of technical knowledge but rather political and cultural views. All of the most cost effective measures are technically very simple, like lowering speed limits in cities and towns, reducing public parking and banning external shopping centers. 

Because of this I'm wondering if I would do more good in focusing on shifting the cultural view. I'm interested in the Transition towns movement and the appeal a more local and slower life seem to have for many. I'm also member of a bicycle promotion organization and doing some smaller activities there. However my full time work as a consultant doesn't leave me with much time or energy to focus on these activities. I'm wondering if I should try to reduce my hours at work, or if my employer doesn't agree to that quit and work with something else entirely that might pay less but give me more time and energy to spare. 

Another option could be to keep working as a traffic planner but maybe try to find a position with a bit more mandate. 

What's your thoughts about this, or generally about the question of working inside or outside the system.