Forcing better public input would be one strategy, I would suggest that public input should simply be ignored. Traffic flow patterns and safety are a science. It isn't a question of taste, there is an empirical 'best' way to design infrastructure. Public input belongs on things like public art projects, and what type of flowers to plant in the community gardens. How fast traffic should flow is not something that should be decided by anybody's uninformed opinion, regardless of whether or not they stand to gain.