The turning radius is the space a vehicle needs to make a certain turn, usually within the confines of a road. When new streets are designed or routes for transportation are planned it is essential that architects and engineers keep in mind the turning radius of the vehicles that will use that street.
Turning radius vs turning circle
The term turning radius is a technical term that has become popular automotive jargon. In the jargon sense, it is commonly used to mean the full diameter of the smallest circle, but in technical usage the turning radius is still used to denote the radius. The less confusing term ‘turning circle’ avoids the mistaken jargon use of the word ‘radius’. It is often used as a generalized term rather than a numerical figure. For example, a vehicle with a very small turning circle may be described as having a ‘tight turning radius’.
‘Curb’ vs ‘curb-to-curb’ turning circle
Usually, two different measurements can be quoted for a vehicle. A ‘curb’ or ‘curb-to-curb’ turning circle will show the straight-line distance from one side of the circle to the other, through the centre. The term ‘curb-to-curb’ indicates that a street would have to be this wide before this car can make a u-turn and not hit a street curb with a wheel. A notable exception in this description is of vehicles that are capable of spinning around their central axis, such as certain lawnmowers and wheelchairs as they do not follow a circular path as they turn. In this case the vehicle is referred to as a “zero turning radius” vehicle.
To download the vehicle turning circle drawing in AutoCAD 2007 format (*.dwg), click on the link below. (Note: You will require an active CAD Architect account.)