Division 4.1.5 Minimum braking characteristics (BP13)
United Kingdom
- (a)
High-speed trains incorporate a speed control system with different deceleration levels. The prescribed performance levels defining the minimum braking power for trains suitable for working on all high-speed lines are given in the two following tables. Meeting these performance levels and the safe operation of the braking system, for new systems, shall be fully demonstrated.
- (b)
It is important to note that the values in Tables 4.1.5c and 4.1.5d are those appropriate for rolling stock and they shall not be interpreted as being the parameter values for defining the braking curves required by the control-command sub-system. These require the essential safety margins for rail operations in all conditions to be taken into account. These margins shall be specified, for the lines concerned, in liaison with the control-command subsystem.
- (c)
Performances: the interoperable trainsets shall be able to achieve, over the range of speeds shown, the average decelerations listed hereafter.
Table 4.1.5c te(s) Equivalent time of application.
Braking mode te(s) Minimum deceleration under set braking conditions (m/s)2 330 to 300 (km/h) 300 to 230 (km/h) 230 to 170 (km/h) 170 to 0 (km/h) Case A — emergency braking with certain equipment isolated 3 0,85 0,9 1,05 1,2 Case B — emergency braking with certain equipment isolated and unfavourable climatic conditions 3 0,65 0,7 0,8 0,9 Note:
Emergency braking applications in Case A and Case B shall be performed under the following conditions:
Case A
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level track and normal train load (number of seats × 80 kg)
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dynamic brake of a motor traction module isolated.
Case B
In addition to the conditions in Case A, the following shall be added:
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one pneumatic brake distributor is isolated;
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reduced wheel-rail adhesion;
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friction coefficient between pad and disc reduced by humidity.
Note 1:
On existing infrastructures, infrastructure managers may define further requirements because of the different signalling and control systems on their part of interoperable networks, (infrastructure register), e.g. additional braking systems or reduced service speeds for given braking distances.
Note 2:
Normal service braking conditions are defined in Section 4.3.7.
- (d)Stopping distances
the stopping distance ‘S’ calculated as a function of the minimum decelerations defined above can be defined by using the formula:
where:
V0initial speed (measured in m/s)
speed given in Table 4.1.5c (measured in m/s)
specified deceleration over the speed band under consideration (measured in m/s2)
equivalent time of application (measured in s)
For example, the stopping distances to be met from specific initial speeds are given in Table 4.1.5d:
Table 4.1.5d
Braking mode te(s) Stopping distances must not exceed 330—0 (km/h) 300—0 (km/h) 250—0 (km/h) 200—0 (km/h) Case A — emergency braking with certain equipment isolated 3 4 530 3 650 2 430 1 500 Case B — emergency braking with certain equipment isolated and unfavourable climatic conditions 3 5 840 4 690 3 130 1 940 - (e)
Supplementary conditions:
For cases A and B, when emergency braking is considered:
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the contribution of electric dynamic brakes can only be included in the calculation of the performances defined above if their operation is independent of the presence of voltage in the catenary,
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the contribution of brakes independent of adhesion and based on retardation caused by the generation of eddy current in the rails can be included in the emergency braking performances, under the conditions defined in Section 4.2.15,
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in this case, the condition that an independent eddy current brake module shall be isolated shall be added to the conditions stated in Cases A and B of Tables 4.1.5c and 4.1.5d,
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electromagnetic track brakes independent of wheel/rail adhesion shall be available for emergency applications on all lines.
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