SPATIAL TRANSITION CURVES AS A GEODETIC GRID OF A GIVEN SURFACE

In the normal treatment of skidding equilibrium on a superelevated curve (a treatment which is based on the assumption of the rigidity of the vehicle and of considering as a plane problem one which is essentially spatial) it is supposed that the resultant of the weight and centrifugal forces applied to the vehicle centre of gravity, are constantly normal to the trajectory which the carriageway maintains with the vertical plane containing the vector of centrifugal force. More usually, in road and rail construction, the carriageway constitutes a grid, which renders inappropriate the generally applied dictum of normality between the resultant force and the carriageway surface. This paper presents a treatment of spatial transition curves as a geodetic grid of a given surface. (TRRL)