The Common Council approved a measure Tuesday that would allow "traffic-calming" devices, such as mini-roundabouts, to be placed in speed-plagued neighborhoods - if local residents agree to pay 90% of the bill. The proposal would not prevent the city from installing the devices where officials decide they are necessary. Rather, it would give residents and local aldermen a way to approach the problem of slowing traffic on their own. The measure passed 14-1, with Ald. Joe Dudzik objecting.