Abstract
It is relatively useless to make pronouncements on what, in certain circumstances, is a safe driving speed for road users; it is interesting, however, to indicate what is an optimum speed from the social point of view, after weighing up the various pros and cons, including safety. Ultimately this is a question of personal preference, and it is the politician's preferences that determine policy and measures. Knowledge of the factual relationships is useful to the political weighing-up process.