In the UK it is 30mph for a single carriageway road (one lane in each direction) in a built up zone unless otherwise stated. However there is a loophole known as the 10%+2. This means you could in theory get away with driving 35mph in a 30 zone but you must allow for speedometer calibration because if you are doing 36 you have no defence and will have to pay whatever fines you incur. I have no idea of US speed limits.
If the runway is in the city, the speed limit is 20 miles per hour unless otherwise posted.
55mph
Whatever the posted speed limit is.
The speed limit is 49.7 (50) miles per hour.
When it is flashing the speed posted is the limit
55 on the highway, and 30 in the city.
55, in the city, 65 or 70 outside of the city. (U.S.)
The speed limit will vary depending upon the city you are in and the exact street you are on. Many residential streets have 25 mph speed limits.
The speed limit on Interstate 90 in South Dakota is 80 mph or 128.7 km/h, except in city limits where the speed limit is lower, usually 55 or 65 mph.
If the runway is in the city, the speed limit is 20 miles per hour unless otherwise posted.
55mph
I doubt many people could walk the speed limit. Maybe in a school zone where the limit is 15 miles per hour. However, since the speed limit is a maximum, it doesn't matter.
10 Mph
Excessive speeding is the driving beyond the neighborhood or the city's speed limit for a certain area. For example, if the speed limit is 50mph and someone drives at 51mph, that is speeding.
826 limit
the posted speed limit
When another speed limit sign is reached that changes the limit from the previously posted one.