A368 / B3134 HGV Study Results

APPENDIX B

 

A368 / B3134 HGV Study Results

 

The two main data sources referenced in this note are:

 

·        A Review of Heavy Goods Vehicle Traffic Using the A368 and B3134, September 2006, jointly commissioned by North Somerset and Somerset County Councils (hereon called survey A, interviews undertaken at points ‘A’ on the diagram below)

·        HGV Survey Data to monitor the effects of the Banwell (West St) closure undertaken in February / March 2006 (hereon called survey B, monitoring points located at points ‘B’ on the diagram below)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


This note is set out as follows:

 

Heading                                             Page

 

Background                                                2

HGV Flows on the A368               2

            Conclusion                             2

HGV Flows on the B3134             2

            Conclusion                             3

Data Robustness                           3

Results                                              3

            A368                                       3

            B3134                                                4

Summary                                          4

 

 

If you have any queries on the content of this note, please contact Stephen Walford, Principal Transport Planner, on 01275 888519 or at stephen.walford@n-somerset.gov.uk

 

Background

 

The A368 (and the adjacent A371 through Banwell) has been the subject of a number of monitoring and data collection exercises over the last few years.

 

The decision was taken to update the July 2004 study ‘A Review of Heavy Goods Vehicle Traffic using the A371’, in order to determine whether it was appropriate to consider placing some form of restriction on this stretch of road.

 

HGV Flows On the A368:

·        Survey A showed that there was a (weekday) average of 68 HGVs using the A368 eastbound at Ubley. On the day of the roadside interviews (RSIs), there were 69 counted, indicating a true representation of the HGV flows.  

·        The North Somerset Council annual monitoring done in Ubley at the same location as Survey A, counted 68 HGVs travelling east in September 2005, and 36 HGVs in September 2006.

 

However, as per DfT guidelines, all vehicles over 3.5 tonnes are included as HGVs for the purposes of ‘HGV monitoring’. The actual numbers of vehicles over 7.5t is smaller:

 

·        Survey A showed that there were 26 vehicles over 7.5t (out of 69)

·        Survey B showed that there were 44 vehicles over 7.5t (out of 68[1])

·        Previous year’s data for vehicles specifically over 7.5t is not available from the annual monitoring, but measures were put in place to record this in September 2006. This showed that there were 24 vehicles over 7.5t (out of 36)

 

There is good correlation between the Survey A results and the annual counts. The numbers recorded in Survey B are slightly higher due to this survey being located at the junction to the west of Compton Martin and therefore deliveries to farms or businesses to the west of the interview point in Ubley will not be counted in the Survey A data. A high level of confidence can be had in the data. 

 

Conclusion

That the two sets of data correlate well in terms of numbers of HGVs, and that confidence can therefore be had in the reliability of the data.

 

HGV Flows on the B3134

·        Survey A showed that there was a (weekday) average of 200 HGVs using this stretch of road (both directions). On the day of the roadside interviews (RSIs), there were 206 counted, indicating a true representation of the HGV flows.  

·        Of these 206, the number that were over 7.5t was recorded as 156.

 

These 156 HGV movements break down as follows:

·        85 were travelling east

·        71 were travelling west

 

This compares with Survey B data that recorded the following:

·        92 travelling east

·        94 travelling west

 

Conclusion

The number of HGVs counted by both Survey A and Survey B are broadly similar and indicate that the data is reliable.

 

 

Data Robustness

Although there is no method to directly check between Survey A and earlier (July 2004) RSI data (simply because previous studies have not focussed on this stretch of road, and it is imperative to compare like with like), it is possible to justify the results because Survey B covered a wide area and therefore has data samples that can link both sets of results:

 

 


                                                                                               

 

 

 

 

 


·        Survey A can be justified by Survey B as the results around Ubley are similar.

·        Survey B can be justified as the results around Locking on the A371 accord with what was found in the July 2004 HGV Study (using RSIs). (where Survey B recorded 182 HGV movements, the 2004 study recorded 219)

·        Therefore a good level of confidence can be had that the data from the current Survey A is reliable.

 

 

Results

 

A368

The results from Survey A show that, on the A368 (heading east), 88% of vehicles were there appropriately. The definition of ‘appropriate’ is of course subjective, but for the purposes of analysis it was taken to mean that the vehicle in question had an origin or destination within 10 miles of the surveyed routes. Whilst this may seem arbitrary, it is felt that this is a reasonable distance so as to include journeys that would have to navigate an unacceptably large diversionary route in order to utilise the recommended regional strategic freight routes[2].

 

For information, the result of the July 2004 study on the A371 (adjacent to the A368 through Banwell), showed that 70% of vehicles were there appropriately.

 

The explanation for the variation in percentages is that the numbers being analysed are very small. Survey A recorded 88% ‘appropriateness’ on only 26 vehicles over 7.5t, whilst Survey B recorded 44 vehicles. The reasons for the difference are understood to be local deliveries in Ubley and Compton Martin from a western origin who would make their delivery and then retrace the journey (therefore not continuing on the A368 to be counted at the interview site).

 

Supplementing this data, is the manual count done on the 28th September 2006, which showed that there were 24 vehicles over 7.5t travelling east on this stretch of road. What this confirms is that results in the ranges that have been observed are representative, with three surveys undertaken within the space of 8 months, all showing results within a range of 20 vehicles.

 

B3134

The results from Survey A show that, on the B3134 (heading east), 86% of vehicles were there appropriately. Again, the definition of ‘appropriate’ was taken to mean that the vehicle in question had an origin or destination within 10 miles of the surveyed routes.

 

Heading west on the B3134, the results from Survey A show that 72% of HGVs were there appropriately.

 

 

Summary

 

It is assumed that any restriction on the B3134 is undeliverable due to the need to gain support from Somerset County Council, which will not be forthcoming. Therefore the focus of technical deliberations should be on the evaluation of the justifications for considering a restriction on the A368.

 

The technical analysis of the results available, show that the numbers of vehicles over 7.5t using the stretch of the A368 that was surveyed, is small – amounting to numbers in the range of 57 to 85[3] per day for two-way traffic. Of these, it has been found that between 70-88% are there appropriately using the lowest and highest figures from all survey data[4].

 

This would mean that there is scope to ‘remove’ in the region of 7-25 vehicles from the two-way flow of HGVs. However it should be noted that, as this stretch of road passes into Bath and North East Somerset, support from them would be necessary in order to implement a restriction. The council has received confirmation that this support would not be forthcoming.

 

Taking into consideration the substantial cost of implementing such a restriction, coupled with the fact that the Police have confirmed that enforcement is unlikely, it seems unlikely that this scheme would represent good value for money.

 

This is further confirmed as any contribution towards JLTP targets would be minimal, and thus implementation of this scheme would divert resources away from other, more effective schemes that could enhance the council’s performance and hence provide a more valuable contribution to delivering transport improvements in North Somerset.


[1] Exact numbers were not counted on the same day, therefore this is the number from the 2005 monitoring figures.

[2] The recommended routes are those as set out in the South West Regional Freight Map as agreed by the Regional Freight Forum and currently contained within the draft Regional Spatial Strategy. In the immediate vicinity of the site in question, these routes are; M5, A38,  A37, A39, A370 and A371.

[3] 57 was the total 2-way HGV numbers recorded in Survey A, whilst 85 was the total 2-way recorded by Survey B.

[4] 70% was the figure from the July 2004 study, whilst 88% was the result from the most recent 2006 study.