British Rail TOPS first arrangement

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At the end of the 1960s, British Railways adopted the Total Operations Processing System (TOPS), a computerised system developed by the Southern Pacific Railroad in the United States. All types of locomotive and multiple unit received a TOPS classification, but the first attempt at applying TOPS was soon modified. This page explains the first attempt at using TOPS and cross-refers the classes allocated with those adopted in the successful re-arrangement. An explanation of the final arrangements for TOPS classification may be found here.

[edit] Locomotives

The first attempt to apply TOPS differed from the later approach in two significant ways:

  • xx/0 was not a valid sub-class number. When the second arrangement was applied original subclasses xx/1 became xx/0, xx/2 became xx/1 and so on.
  • Some detail differences within classes were considered sufficient for a different class number to be allocated, rather than indicate it with a sub-class. In addition, there are a number of cases where conversions led to complete reclassification, where similar circumstances later would be indicated simply by allocating a new subclass. The change in approach led to some odd gaps in the list of locomotive classes when they were re-arranged as the principal class numbers were retained unaltered. Classes affected by this change in approach include:
    • Class 29 (re-engined Class 21)
    • Class 31 (re-engined Class 30)
    • Class 34 (became Class 33/1)
    • Class 43 (North British Locomotive-built Class 42)
    • Class 48 (Class 47 with experimental engine)
    • Class 72 (became Class 73/0)

[edit] Diesel Multiple Units

The first attempt to apply TOPS to diesel multiple units saw each carriage within a unit being allocated its own unique class number. This was probably because most DMUs were not kept in permanent formations. Classes were allocated according to the following division:

100-131: Driving Motor cars
140-150: Driving Trailer cars
160-190: Trailer cars
201-203: DEMU Driving Motor cars
211-212: DEMU Driving Trailer cars
221-225: DEMU Trailer cars
    251: Express DEMU Driving Motor cars
    261: Express DEMU Trailer cars

However, this arrangement was later revised so that each unit adopted the class number previously given just to the main type of Driving Motor car (the exception being the DEMU units, which were completely changed). The table below cross-references the old and new TOPS classes:

First TOPS Second TOPS First TOPS Second TOPS First TOPS Second TOPS First TOPS Second TOPS
102 101 106 105 140 104 141 105
142 108 143 100 144 101 145 103
146 109 147 111 148 114 149 121
150 122 160 104 161 107 & 108 162 101
163 110 164 101 165 111 166 104
167 108 168 101 & 111 169 104 170 105
171 101 172 116 173 115 174 118
175 116 176 117 177 115 178 119
179 120 180 124 181 124 182 123
183 123 184 123 185 125 186 127
187 126 188 126 189 126 190 130
201/1 201 201/2 202 201/3 203 202/1 206
202/2 207 202/3 205 203 204 211/1 206
211/2 207 211/3 205 212 204 221/1 201
221/2 202 221/3 203 222/1 206 222/2 205
223/1 201 223/2 202 223/3 203 224 207
225 203 261 251

[edit] Electric Multiple Units

The first attempt to apply TOPS to the Southern Region's fleet of electric multiple units, saw classes being allocated according to the following division:

40x: Southern Railway designed units
41x: 1951-type British Railways designed units
42x: 1957-type British Railways designed units
43x: 1963-type British Railways designed units
44x: 1967-type British Railways designed units
45x: Underground ('Tube'-sized) units
46x: 1971-type British Railways designed units

In comparison with the later re-arrangement, it is worth noting that types that were different were given the same class (e.g. the single-car luggage vans) and identified only by sub-class, while those that were later treated as variations of the same class, were separated according to their construction period (e.g. early or late 1950s builds). When the new arrangement was applied, 40x classes were left untouched, but the others were changed as follows:

First TOPS Second TOPS
411 415/1
412 414/1 & 414/2
413 416
414/1 411/1
414/2 410/1
421/1 411/2
First TOPS Second TOPS
421/2 410/2
422/1 419
422/2 499
423 415/2
424 414/3
431/1 421
First TOPS Second TOPS
431/2 420
432 423 & 480
441 430
442/1 492
442/2 491
First TOPS Second TOPS
451 486
452 485
453 487
461 446
462 445
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British railway rolling stock numbering and classification systems