DELIVERABLE 2.8 - urban track

D0208_STIB_M24.doc
TIP5-CT-2006-031312 Page 25 of 44
URBAN TRACK Issued: August 13, 2008
Quality checked and approved by project co-ordinator André Van Leuven
3.2. BASIS OF ATM – CURVE, COMPARISON OF KINEMATICS AND DYNAMICS
Figure 3.2
The main difference between the standard curve (clothoid) and the Viennese Curve is in the advanced
line management. The advantages of the modern geometry are obviously. The centre of gravity
guidance of the vehicle is optimised and has very low and continuous accelerations and low guiding
forces. The track is continuously defined while its loading is minimal and known. The track alignment
height is based on the centre of gravity. Due to the smooth ramp, transition low decay rates of the track
are expected and demonstrated.
The following picture shows the curve driving powers which affect the track and the vehicle and due the
passengers.
Curve Driving Powers at the drive over a curved track
The transition curves used so far had straight cant gradients. The impact of substantial forces at these
transitions has resulted in greater rail and wheel wear. Such conventional transitions also reduce the
passengers’ ride comfort and safety by causing noticeable transverse jerks. In addition, such areas
frequently develop track geometry defects.
The Viennese Transition Curve provides for a verifiable reduction of rail wear in curves and for an
extended life cycle in comparison with a conventional alignment geometry based on clothoid and straight
cant gradients. Moreover, the new design feature improves the accuracy of track position. The advanced
track alignment used for the Viennese Transition Curve is the key to maintaining the desired track
geometry. This in turn will extend the life cycle and reduce life cycle costs. In addition, the constant and
non-jerking movement of vehicles obtained in curves will greatly improve passengers’ riding comfort
and safety.