Metro Train Simulation

Emergency Braking Distance Calculation

Emergency Braking Distance (EBD) Calculation :

Emergency Braking Distance (EBD) is equivalent to the distance covered by a moving train to standstill, on application of Emergency Brake (i.e. only pneumatic brake application through brake pipe) considering failure of all brake control electronics of the train. Please input the following parameters for EBD Simulation :





# NOTE : Please read Para 'Limitations of online EBD simulation tool'. This is an online demo simulation tool and results of online EBD simulation tool may have some error due to these limitations. However, our offline software tools do not have such limitations and provide much accurate simulation results. For detailed description of technical terms used in this simulation tool, please read 'Technical Terms' & 'Performance Parameters' sections of this website.

Braking Effort vs Speed Graph of Train :

In the above graph:


OA:
Value of total Braking Effort of train in KN at standstill
OE:
Value of total Braking Effort of train in KN at speed of 'OE'
FC:
Value of total Braking Effort of train in KN at speed of 'OF'
GD:
Value of total Braking Effort of train in KN at speed of 'OG'

Note :- User may input equal value of 'OA' & 'EB' / 'FC' & 'GD' (i.e. OA=EB & FC=GD) , if 'AB' & 'CD' portions of BE graph are horizontal.

Delay Time Parameters of Braking System :

In the above graph:

t1 - t0:
Absolute delay time required to appears pneumatic braking
t2 - t1:
Delay ime required to build up full pneumatic brake in complete train through brake pipe pressure drop only

A linear transient of braking force is considered in EBD simulation tool. Hence, the braking equivalent activation time 'tb' is obtained by adding the absolute delay and a half of the full braking force build up time. Following formulas may be used to calculate the braking equivalent activation time as function of the passenger train length L in meter for emergency braking through brake pipe only :

tb = 3.5 + 0.15*( L/100 )2


Note : Above formula is not applicable to calculate the braking equivalent activation time for service brake application through brake control electronic.

Limitations of online EBD Simulation Tool:

In this simulation tool, it is assumed that the value of brake friction coefficient remains constant during full speed range and train is developing specified braking effort as per given Braking Effort Vs Speed graph. However, in actual, the value of friction coefficient does not remain constant in complete braking operation and a small variation is observed in the value of friction coefficient with change in brake block temperature, train speed and other environmental conditions.

Calculation of EBD can not be calculated on the basis of brake block type, pressure in brake cylinder, area of brake cylinder & break shoe etc.