Division 4.1.1 Maximum track forces (BP4)

In addition to basic parameter BP10 that deals with the static axle load, the characteristics that allow the maximum track forces to be defined are:

• the dynamic load applied to the rail by the wheel,

• the transverse forces exerted on the track by the train.

1. (a)

   Dynamic load

   The maximum vertical load to be exerted by the wheels on the rail (dynamic load of wheel Q) is defined as follows:

   • for rolling stock designed to operate on specially constructed high-speed lines at speeds equal to or greater than 250 km/h, the following values apply:

     V (km/h)	Q (kN)
     V = 250	180
     250 < V ≤ 300	170
     V > 300	160

   • for rolling stock designed to operate on specially upgraded high-speed lines at speeds of the order of 200 km/h:

     • F1the technical rules in use on these lines are applicable.

2. (b)

   Transverse track forces

   Interoperable rolling stock shall comply with the Prud'homme criteria for the maximum transverse force ΣY defined as follows:

   • total dynamic maximal transverse effort exercised by an axle on the track:

     $${\left(\mathrm{\Sigma {\rm Y}}\right)}_{\max }=\mathrm{10\; +}\frac{P}{3}\mathrm{kN,}$$

     P being the static load on the axle in kN. This result of this formula defines the limit of adhesion between the track tie and the ballast under the influence of transverse dynamic efforts,

   • quotient of the transverse and vertical efforts of a wheel:

     $${\left(\mathrm{{\rm Y}/Q}\right)}_{\lim }\mathrm{=\; 0,8,}$$

     Y and Q expressing respectively transverse dynamic effort and vertical effort exercised by a wheel on the rail. This limit characterizes the risk of a wheel climb on the rail.

3. (c)

   Longitudinal track forces

   Longitudinal forces exerted on the track by the rolling stock shall always be less than those corresponding to an acceleration or a deceleration of 2,5 m/s².