Questions of what a self-driving car ought to do if it encounters a situation analogous to the 'trolley problem' have dominated recent discussion of the ethics of self-driving cars. This paper argues that this interest is misplaced. If a trolley-style dilemma situation actually occurs, given the limits on what information will be available to the car, the dynamics of braking and tyre traction determine that, irrespective of outcome, it is always least risky for the car to brake in a straight line rather than swerve.
Keywords: Automation; Ethics; Risk; Self-driving cars; The trolley problem; Vehicle dynamics.