TOPIC 33 FREIGHT - 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.

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 of NI lorries.  These are included in the RT data but not in the CSRGT data

Comment;  It should  say 3.6% of HGV traffic on GB roads. Together the NI and Foriegn HGVs provide 1035m vehicle-km.

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 RT classification.  RT provided 5.6b veh Km.  The CSRGT combination provided 1.7b – see table below. 

Comment: There is heavy use of the word “may”.  Is it really so that enumerators count 6-axle vehicles with one raised as though with 5-axles or is it only the Automatic Traffic Counts, ATCs,  that do that? 

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 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.(nos, 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 percentages are very much, if not catastrophically, larger.

Appendix F

No attempt is made to correct the estimates of tonne-km or tonnes lifted.

TSGB 0401 provides data which appears to compare road freight with rail, water and pipe line.  Whether or not there is survey error in the road freight data, it excludes freight in foreign, and NI lorries.

We say best estimates of road freight on UK roads are to be had by calculating the average loads by vehicle type from the CSRTG data and applying those to best estimates of Goods Vehicle vkms from the RT survey.

In that context we:

1. Estimated the number of non-goods HGVs by subtracting the 389,9000 vkms in Table VEH 0103 from the 470,1000 vkms in table VEH 0102.  That provides 80.200 non-goods HGVs
2. Split the 80,200 non-goods vkms equally between 2-axle rigids and 5-axle artics and assigned 8,000 km per year to each of those vehicles.  Subtraction from the RT estimates for those classes of HGVs provided estimates for goods vehicle vkms.
3. Adjusted the numbers in the classes by assuming 35% of 6-axle artics had one axle raised thereby being incorrectly counted as 5-axle artics.  Similarly we assumed 10% of 5-axle artics, 5% of 4-axle rigids and 5% of 3-axle rigids had an axle raised.  (4-axle artics were combined with 3-axle artics.  Consequently no correction was applied there).  Those adjustments do not affect the total number of vkms. Instead the adjustments alter the vkms in each class.

Multiplying by the corresponding tonnes per vehicle and summing yields 174.6 billion tonne-km (excluding freight in light goods vehicles).  The original Freight Stats provide 139 bn Tonne-km with no Light Goods, RFS0107, and 151 bn with Light Goods, TSGB 0401.  Hence the light goods element totals 12bn tonne-km   Adding that to the 174.6bn provides 186.6bn as the better number for road freight.  The 186.6bn is 23.6% above the value of 151bn cited in TSGB 0401. 

The following table provides comparative data (all for the year 2010):

The comparison of the RT adjusted with the CSRGT unadjusted vehicle flows is fair particularly after noting that the RT value for 5-axle artics includes 1035 million vkms for foreign and NI lorries excluded from the CSRGT.

Transport Watch

17^th February 2013

PDF: 

TOPIC 33 Discrepancy Report Comment.pdf