Dear,, in case there is no vehicle in one of the lane where u want to cross,(most of the signals are censor based.) signal will not operate.Now, any person want to cross the lane where this pedeatrian crossing button are not available,sure signal will not turn to green to cross(censor Based).if any one press this button signal will activate, hope is clear!!!!!!!!

Note:in doha most of the place pedestrian signal light are not working as it really required>>>>