Traffic Assessment - Renfrewshire Council

Meeting at Renfrewshire Council JobNo. SCT3526
31 October 2012
Table 3 of the note indicated the ratio of external and internal trips by mode and included a
comparison of the trips generated, and subsequently discounted, by the 2,500m 2 foodstore.
JE agreed the methodology of calculating the ratio of internal and external trips was
acceptable. JE also confirmed it is appropriate to discount the internally generated trips from
the wider local road network of Bishopton Village.
d) Pass-by / Diverted Trips – SL set out JMPs proposal to discount pass-by / diverted vehicle
trips from the ‘total’ external vehicle trips. It was agreed by all that 30% pass-by / diverted is
acceptable and this would likely be a mix of pass-by trips from the employment opportunities
in Dargavel and from the park and ride and diverted trips from the existing Bishopton Village
(returning from work).
SL proposed that pass-by trips from Dargavel employment opportunities and the park and ride
would already be included in the vehicle trip calculations for the Masterplan. SL also proposed
that any diverted trips to the new store from Bishopton would be locally reassigned
movements on the immediate local road network, therefore having no impact on traffic
volumes. JMP therefore propose to discount 30% pass-by trips from the total vehicle trips,
thereby providing a final net-increase of 191 two-way vehicle trips on the wider local road
network of Bishopton, during the weekday PM peak period. JE confirmed this is acceptable.
e) Distribution & Assignment – The distribution of vehicle trips to / from Bishopton will be based
on a gravity model using population census output areas for Bishopton. JE agreed this is
acceptable.
The assignment of traffic to the local road network will be based on travel times with 100% of
traffic via Station Road. JMcD advised that the northern and southern access points are likely
to be constructed and linked via Dargavel by the time the foodstore is opened. SL highlighted
there is therefore an alternative route for residents from the northern area of Bishopton. JE is
reluctant to discount any further traffic that could go through Station Road and while it is
accepted there may be an alternative route, the TA should still consider 100% via Station
Road in the first instance.
4. Growth Factor
JMP assumes there will have been little or no growth in background traffic since traffic surveys
were previously carried out in 2005. JMcD confirmed traffic surveys have been carried out along
the A8, Station Rd and Rossland Crescent and these will be used to determine the actual level of
growth.
JE confirmed 0% growth would be acceptable if supported by the recent surveys.
Note: It was generally agreed that should the recent traffic surveys demonstrate a reduction in
traffic volumes, the flows used for the 2008 TA would be used to provide a robust analysis as all
transport interventions have been based on the previous analysis.
5. Assessment Years
JMcD confirmed the year of completion for the full Dargavel Village is currently estimated to be
around 2027 / 2028. In terms of the opening year of the foodstore, this will be market led but is
likely to be around 2020.
JE agreed that as the local roads infrastructure will be in place before Dargavel is fully built out
and also prior to the opening of the foodstore, it is acceptable to assess a year of completion only
for all of Dargavel i.e. 2027 with traffic growth if required.
6. Committed Developments
SL presented a table indicating all of the committed development that had been considered by the
2008 TA. JE confirmed which developments had been completed and those developments where
consent had lapsed or commencement had been delayed (primarily due to the recession).
While it was acknowledged that the TA currently being prepared for the foodstore does not need
to consider developments where the consent has lapsed, JE requested these are included as they
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