Residential areas really should be 30 km/h. It is proven that when you mix bicycles and motor vehicles together and the pedestrians you can expect on a residential road like this, you get way more casualties at 40 km/h+ than you would had you been driving at 30 km/h or less. It also lowers emissions, gives everyone more time to react, lessens the need for wider lanes, and greatly civilizes residential and even commerical areas. 20 mph zones in the UK and NYC have proven to very successful, millions of people there now live in them. Most people in the Netherlands live on 30 km/h limited residential roads. A number of them live on car free streets. But that is a topic for a future post.
Arterial roads in urban areas should go between 40 and 70 km/h. In general, 50 km/h is a good speed for arterial roadways. For some roads like 91 St in Edmonton at 23 Ave, 70 km/h is a good speed as the type of road makes it work better. Believe it or not, 91 was once intended to be part of a freeway towards downtown. It is very wide, has a wide ROW and wide lanes, and a wide median, for this reason. 70 km/h is a good speed for huge arterials like this. But we must be very careful with applying limits this high. Given the wrong conditions, we can end up with a terrible road. 50 should be the standard.
40 km/h is a good option for some areas like 104 Ave in Oliver, 101 St north of Downtown, 109 St and Whyte Ave in Garneau and Strathcona, and a few other areas. It also means that we don't need lanes as wide as a 60 or 70 limit would. This also includes the design speed. If the posted limit is 50 but the design speed is 60, you can expect most people to go 60, because there is nothing making you feel like that is the wrong speed to go. Calming like narrower lanes, wiggles at unsignalized crossings, roundabouts and speed tables designed to be taken at 50 km/h or less helps Dutch roads look like 50 km/h is a natural speed to follow.
Let's skip over some rural roads like how most township and range roads work and go right to the freeways and divided highway limits.
Freeways are high speed roads, no conflict points except at the ramps, which are usually spaced about 1.5-5 km apart. They have wide lanes, at least two per direction, usually have shoulders, and a median. It comes naturally that these types of roads have high speed limits. Some places like Ontario and Quebec have lower limits, 100 km/h to be exact, or as ridiculously low as the 90 km/h limit on freeways until 1995 in the US after the 1973 Oil Crisis, and as high as no limits, like in Germany most famously and Montana used to do that a while ago until the rule that "reasonable and prudent" was too vague. What could Alberta use for it's freeways? I suggest 130 km/h. Many European use this limit, the Netherlands, with the safest roads in the world, France, Italy, most of Central and Eastern Europe plus most of the Balkans, plus a large part of the Western US, South Dakota, Idaho, Montana, Utah, Colorado and Nevada, all use these limits for their freeways. Germany is much denser and half of it's autobahn system has no limit but an advisory limit of 130, which many people break, and people aren't dropping dead. They have a very low rate of casualties on their freeways. It is as safe and maybe even safer than the low speed limits we have. 110 is exceeded by almost everyone. 120 is what some petitions like this call for. We could go at least to 120, even better at 130. Not many people will go over that. If you see the sign in the bottom left, then 130 km/h is the max you can go unless a sign otherwise says. It can be reduced with variable speed limits, like the one to the bottom right, if needed due to collisions and congestion, or even construction.
It would be the highest in Canada, unless stop100ontario.ca gets their way.
Speed limits can be reformed in the province. Begin today Albertan and municipal governments.