Rounding Rules for railcard-discounted fares

[Paul Kelly]

A search shows there have a been a few previous threads about rounding rules on here, none of them really conclusive, so I thought I would start a new one looking at it from a different angle.

The RJIS Datafeed spec. for fares data contains (on page 48) a description of a list of rounding rules. It does not however say when they should be used, and to the best of my knowledge nothing else in the spec references them. They are however included in the data files that come with Avantix Traveller, and I have included a summary of them below.

Some of them seem really quite elaborate, and I am baffled as to what all the different rules would be needed for. Any ideas or hints or clues that anybody has would be really interesting. As far as I can see, Avantix Traveller just rounds everything to the nearest 5p (which is actually the first rule).

I suppose my main question is, if you were to implement some software that could calculate railcard-discounted fares, would it be acceptable for it just to always round to the nearest 5p. I think it probably would, but I'd be really interested in any historical insights into all these rounding rules and when/where they should be/were used!

There are 36 of them, labeled 1 to 10 and then A to Z. Some of them are duplicates of others:

01: Round all fares to nearest 5p
02: Round all fares to nearest penny
03: Round all fares to nearest 50p
04: Same as 03
05: Round all fares to nearest 10p
06: Fares up to £20.00, round to nearest 10p. £20.01 and above round to nearest 50p
07: Same as 03
08: Round all fares to nearest pound
09: Same as 02
10: Same as 05
A : Round all fares up to next pound
B : Round all fares up to next 50p
C : Fares up to £14.49, round up to next 10p. Fares £14.50 - £73.99, round up to next 50p. Fares £75.00 and above round up to next pound.
D : Fares up to £9.99, round up to next 10p. Fares £10.00 - £49.99, round up to next 50p. Fares £50.00 and above round up to next pound.
E : Fares up to £9.99, round up to next 10p. Fares £10.00 - £29.99, round up to next 50p. Fares £30.00 and above round up to next pound.
F : Round all fares up to next 10p
G : Fares up to £29.99, round up to next 10p. Fares £30.00 and above round up to next 50p.
H : Fares up to £19.99, round up to next 50p. Fares £20.00 and above round up to next pound.
I : Round all fares up to next 20p
J : Fares up to £24.99, round up to next 10p. Fares £25.00 to £99.99, round up to next 50p. Fares £100.00 to £249.99, round up to next pound. Fares £250.00 and above, round up to next £5.
K : Fares up to £9.99, round up to next 10p. Fares £10.00 to £19.99, round up to next 50p. Fares £20.00 and above round up to next pound.
L : Round all fares up to next 10p
M : Round all fares up to next 5p
N : Fares up to £14.49, round up to next 10p. Fares £14.50 and above, round up to next 50p.
O : Same as B
P : Same as A
Q : Same as A
R : Same as L
S : Round all fares up to next £5
T : Same as B
U : Same as L
V : Same as B
W : Fares up to £9.99, round up to next 10p. Fares £10.00 to £29.99, round up to next 20p. Fares £30.00 to £39.99, round up to next 50p. Fares £40.00 and above, also round up to next 50p!
X : Fares up to £9.99, round up to next 10p. Fares £10.00 and above round up to next 50p.
Y : Fares up to £14.99, round up to next 10p. Fares £15.00 and above round up to next 50p.
Z : Fares up to £14.99, round up to next 10p. Fares £15.00 to £99.99, round up to next 50p. Fares £100.00 and above round up to next pound.

 

[hairyhandedfool]

I was always taught to round up to the nearest 5p.

Railcards are advertised as 1/3 off, but are actually worked out at 34% off, so rounding up only puts the discount below 1/3 off for some fares normally below £5.

 

[wibble]

The rounding rules relate to % increases applied to fares, generally at the January fares round. If you're applying an RPI+1% increase to regulated fares, the rules will round the fare up or down as appropriate.

e.g. A CDR at £10 is increased by RPI+1% (5.8% for January 2011). This would mean that the fare increases to £10.58. The CDR uses Rounding Rule 5 which rounds to the nearest 10p - i.e. £10.60.

Each rule is linked to a particular ticket type, although most of the rules are no longer used.

 

[Paul Kelly]

Thanks for that insight; it seems to make sense. If I understand correctly then the computer system that hosts the fares database has a built in mechanism for automatically increasing all the fares (how useful :roll, and these rounding rules are used to ensure that the increased fares are all set to sensible values.

Might it then be a mistake that the rounding rules are included in the RJIS datafeed, since they aren't actually required for calculating fares or issuing tickets?

 

[John @ home]

the computer system that hosts the fares database has a built in mechanism for automatically increasing all the fares

Increasing or, in January 2010, reducing all the regulated fares.