Topic 33 Discrepancies report comment
Discrepancies report Comment
Top of page 3 provides “79% of licensed HGVs are commercial”.
Comment: Table VEH0102 provides 470,100 HGVs and Table VEH 0103 provides 389,900 goods veh. Hence Goods vehicles as a percent of the whole are (389.9/470.1) = 83%, not 79%. Perhaps they worked it out incorrectly thus [(470/389.9)-1] = 79%, or have a different data source. (No - they uused other numbers and correctly)
Page 2, Geographical coverage. It says, “Foreign HGVs account for 945m vkms of total traffic (3.6% of traffic of GB roads)”. There are also 90m vkms for NI lorries.
Comment; It should say 3.6% of HGV traffic on GB roads. They corrected that in May 2013
Page 3, 5-axle artics: It says, “The RT estimate of 5-axle articulated HGV traffic is 4 billion vkms higher than the CSRGT estimate. Reasons for this difference include the treatment of HGVs with trailers as articulated by the RT estimates ….”
Comment: That cannot be correct. The CSRGT subdivides by trailer and type. Our subsequent combinations match the RTS classification. RTS provided 5.6b veh Km. The CSRGT combination provided 1.7b – see table below.
|
|
Bn Veh –km 2010 |
|
|
RTS |
FS |
|
|
2- rigids |
10.0 |
5.9 |
|
3- rigids |
1.8 |
1.6 |
|
4 + rigids |
1.5 |
1.2 |
|
3-4 artic |
1.5 |
0.9 |
|
5- artic |
5.6 |
1.7 |
|
6 + artic |
6.0 |
7.5 |
|
Total |
26.3 |
18.8 |
Comment: There is heavy use of the word “may”. Subsequently the DfT have said that the axle misclassification is duplicated by enumerators, so as to maintain consistency with the ATC record.
Further, we see raised axles on all HGVs except 3-axle artics and 2-axle rigids (for which raised axles are an impossibility), not just on 6-axle artics.
Page 4 – underreporting: The text says there is underreporting of 20% for rigids and 11% for artics. In Appendix F the observed values are increased by those percentages. There is therefore a mistake since, if the words are correct, the increase on rigids should be the observed value divided by 0.8 or multiplied by 1.25, not 1.2. Similarly for artics: the observed value should be increased not by 11% but by 12.23% or multiplied by the inverse of 0.89. On the other hand it could be that Appendix F is correct, in which case the words on page 4 need to be changed. (They corrected the wording in May 2013 to refer to "uplift"- leaving the numbers unchanged)
Further there is no indication as to whether the underreporting falls proportionally on loaded or empty running. Possibly it is empty running that is the more likely to be underreported.
Page 9, use of HGV estimates: Text contains no advice as to how to adjust the published data. Some of the links overleaf - page 10 appear inert.(Numbers, 2, 4,5 and 6).
Annex B provides differences between the RT and CSRGT. The percentages are with respect to the RT but the table does not make that clear. The same should be published with respect to the CSRGT for which the values are very much, if not catastrophically, larger.
Appendix F
No attempt is made to correct the estimates of tonne-km or tonnes lifted.
Transport Watch
12th March 2011
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