CALGARY City councillors say Calgarians have been asking for lower speed limits in residential areas for years and now they re doing something about it. Drivers will have to go 10 kilometres an hour slower as of May 31 as the residential speed limit is dropping to 40 km/hr. This is the new default speed limit, said Tony Churchill, a senior traffic safety engineer with the city. It s 40 km/h unless otherwise posted, so if there s a posted speed limit, that speed applies and if it s not posted along the length of the roadway, then it s 40. The impact will be small, said Churchill.