09-08-2012, 03:30 PM
d gives the maximum distance to meet the criteria for operability.
1.5BD is rules based and should be an exceptional deviation from normal practice.
Remember, each country has differening rules. It should be stated as an assumption what each acyonym means (i.e. BD, d) and where limits are used (1.5, i.e. UK mainline practice).
Also, mininimum signal spacing is a safety distance. Maximum is an operational figure. The distinction between the two is very important to understand and relay to the examiner.
1.5BD is rules based and should be an exceptional deviation from normal practice.
Remember, each country has differening rules. It should be stated as an assumption what each acyonym means (i.e. BD, d) and where limits are used (1.5, i.e. UK mainline practice).
Also, mininimum signal spacing is a safety distance. Maximum is an operational figure. The distinction between the two is very important to understand and relay to the examiner.
Le coureur