Updated October 2005
Tables 6.2 and 4.1 of Transport statistics Great Britain 2004 provides 41 billion passengerkm and 19 billion tonnekm via national rail. Dividing the passengers by 20 yields 2.05bn coachkm. Dividing the freight by 15 yields 1.27 lorrykm. Adding the two yields 3.32bn (bus plus lorry)km. Maintenance and renewals for the system may be running at between £2 and £3 billion annually for the decade (Table 8.2 of Network Management Statement 2001). On that basis the cost per equivalent bus/lorry vehiclekm has the range (6090) pence. (If the equivalent bus flows are eliminated from the sum on the basis that it would be lorries that do the damage then the cost has the range (157236) pence per equivalent lorrykm). Alternatively divide the £(23) billion by the 32,000 km of track length and get £62,000 £94,000 per trackkm per year. Alternatively again, if we set one tonne as equivalent to one passenger then the infrastructure maintenance cost per (passenger + tonne)km has the range 3.3 pence to 5 pence.
(a)  That the cost per lorrykm was 12 pence (compared with the (6090) pence by rail). 
(b)  The annual cost per lane km has the range £25,000£33,000 (compared with £62,00094,000 per trackkm for rail). 
(c) 
The cost per (person + tonne)km is 0.5 pence, onesixth to onetenth the value for rail. 
The comparison is biased in favour of rail since (a) buses on trunk roads and motorways amount to one tenth of the heavy lorry flow but are ignored when calculating the factors (b) substantial elements of road maintenance such as signs, lighting, verges, hard shoulders, winter maintenance, and some wear and tear should be attributed to vehicles other than to lorries alone.
Table  Lengths, costs and unit costs  Motorways and Trunk Roads in GB
Year 
1999/00 
2000/01 
2001/02 
2002/03 
2003/4 
Total 
Lengthskm TSGB 2004 Table 7.8 

M'way, M 
3,449 
3,468 
3,476 
3,476 
3,476 
17,345 
Trunk, T, excluding M 
11,698 
11,701 
11,369 
10,640 
93,40 
54,748 
Lane Lengths km 

(a) M = 6 T = 2 
44,090 
44,210 
43,594 
42,136 
39,536 
213,566 
(b) M = 7 T = 2 
59,237 
59,379 
58,439 
56,252 
52,352 
285,659 
Expenditure outturn £millions TSGB 2004 Table 1.15 

Capital 
1,079 
1,021 
1,152 
1,395 
1,038 
5,685 
Current 
574 
760 
776 
819 
982 
3,911 
GDP deflator TSGB 2004 Table 1.2 
1.102 
1.087 
1.063 
1.03 
1 

Expenditure £millions 2003 prices 

Capital, (Cap) 
1,189 
1,110 
1,225 
1,437 
1,038 
5,998 
Current, (Cur) 
633 
826 
825 
844 
982 
4,109 
Total 
1,822 
1,936 
2,049 
2,280 
2,020 
10,107 
½(Cap)+ (Cur) (xx) 
1,227 
1,381 
1,437 
1,562 
1,501 
7,108 
vehkm billion: 4 Axle rigids and artics 
11.5 
12.1 
12.7 
12.14 
11.55 
59.99 
Cost (xx) per Lanekm (a) £ 
27,831 
31,238 
32,967 
37,070 
37,965 
33,284 
Cost (xx) per lanekm (b) £ 
20,715 
23,258 
24,593 
27,768 
2,8671 
24,884 
Cost (xx) per Vehkm pence 
11 
11 
11 
13 
13 
12 
System wide passengerkm Billion  696  695  710  734  736  
SystemWide Tonnekm Billion  157  158  157  157  159  
(passenger + Tonne)km Billion  853  853  867  891  895  
% total traffic on Motorways and Trunk roads  36  35.6  34.6  33.7  32.5  
(passenger + Tonne)km on M and T  307  304  300  300  291  1502 
Pence per (passenger + Tonne)km  0.400  0.455  0.479  0.520  0.516  0.473 