St Mary’s Junction Scheme:
an opportunity for increased travel choices
This briefing note has been prepared by People Powered CIC.
People Powered CIC is a Community Interest Company that aims to grow sustainable travel options
on the Isle of Wight. We deliver practical projects, research and strategic transport planning services.
As councillors consider whether to delay the St Mary’s scheme, we would like to provide some
commentary on the rationale for the current scheme and suggestions which could help maximise the
benefits of any investment that does occur at this junction. This paper is intentionally brief, but
references are provided for further information. We would be happy to discuss the issues raised in
more detail with any councillor should that be helpful.

Background
Our understanding is that the junction changes are planned principally to address future increases in
congestion that have been projected by the IWC’s chosen consultants. The solution presented is to
provide sufficient additional motor vehicle capacity through the junction to allow for this projected
growth. A proposed scheme was consulted on in February 2018, and since that time has been
through a major revision and further minor amendments.

Growth projections used for this scheme: how robust are they?
The junction modelling is based on presumed traffic growth of around 22% between 2017 and
2034.1,2 Government population projections suggest the Island’s population can be expected to grow
by around 6.5%3 across the same time period. The software used to calculate growth (TEMPro)
appears to assume a significantly higher number of extra dwellings in the Newport area by 2034
than the draft local plan allocates2. In addition there is evidence to suggest TEMPro can significantly
overestimate growth.4,5,6 Research found that in Devon growth between 2011 and 2014 was
overestimated by up to 20% compared with actual growth.4
Crucially, the 2008 Newport traffic model predicted traffic growth (using TEMPro) of around 26%
in the period 2007-20207, yet in the period 2007-2018 according to the Department for Transport’s
own traffic counts traffic actually decreased by around 1%. 8 The 2008 Newport traffic model was
the basis of the original plans to increase capacity at the junction at St Marys.
Vehicle mileage on the IOW is lower in 2018 than in 2004 and has largely plateaued since around
2002. Based on these various indicators it appears likely the forecast traffic growth is significantly
higher than is actually likely, undermining the case for such a large increase in road capacity at the
junction.

Predict and provide or Transport Demand Management?
The basis of the approach with the St Mary’s junction is to take predictions of growth and then
provide sufficient capacity for it. While this sounds like a common sense approach, evidence tells us
that this “predict and provide” approach actually creates additional traffic - a phenomena known as
“induced traffic” The initial reduction in congestion associated with new road capacity encourages
people to drive at times they might have previously avoided, or use the car when they might
otherwise use another mode, and the benefits of the scheme are soon lost as congestion builds
again. 9,10,11. A more sophisticated approach to transport planning uses principles of Transport
Demand Management (TDM). Rather than having to provide road capacity for all the demand

People Powered CIC – www.people-powered.org.uk – info@people-powered.org.uk

 projected, we can instead take measures to reduce that demand and hence not need to provide as
much capacity.

Opportunities for Transport Demand Management at St Mary’s
Pausing and reviewing the approach to St Mary’s junction presents an opportunity to do a number of
things:
1. Align any proposed junction changes at St Mary’s with a number of other Council policies
and plans that aim to support increases in sustainable travel.
2. Strengthen walking, cycling and public transport provision to shift existing and projected
trips to non-car modes. This can be achieved within the confines of the junction scheme but
can be maximised by spreading improvements slightly wider. Examples of possibilities to
increase capacity for movement of people (rather than cars) include high-quality walking
and cycling routes between St Mary’s Hospital, Dodnor Lane Industrial Estate, the IW College
and Newport Town Centre, and a quality bus corridor upgrade between Cowes and
Newport.
3. Re-assess the realistic additional capacity needed and reduce the scale of the changes. This
would free up space in the existing scheme that could be used to enable improved walking,
cycling and public transport measures to be introduced.
4. Consider how development at Camphill can be delivered to minimise car use. This site offers
a key opportunity for a high level of council control of the development process, enabling a
public transport, walking and cycling focused development. New urban areas have
successfully been created on this basis in various other places.
5. Evaluate the scope for specific measures to reduce peak-time traffic as this is the only time
significant congestion is currently experienced or expected in future.
We believe taking the above approach to St Mary’s junction will lead to a higher quality scheme that
serves the needs of all Islanders by being inclusive, encouraging a cleaner, healthier environment,
improving the quality of the urban realm while reducing congestion and locking in the benefits of the
new scheme for many years to come.

Key statistics
Changes in travel patterns
•

Evidence of reducing car use:
o Car (driver) trips per person in England 2002-2018  10%
o Car (driver) distance travelled per year in England 2002-18  12%

•

Quarter of all car trips are under 2 miles (a distance most people could easily walk or cycle)

(Source: National Travel Survey)
(Source: National Travel Survey)
•

In the 1990s, 80% of people were driving by 30; now this marker is only reached by 45. Men
under 30 are travelling only half the miles their fathers did.
(Source: Are young people going cool on cars? BBC News)

People Powered CIC – www.people-powered.org.uk – info@people-powered.org.uk

 Traffic levels on A3020 (between St Mary’s roundabout and Lonsdale Ave)

All motor vehicles
30000
25000
20000
15000
10000
5000

2018

2017

2016

2015

2014

2013

2012

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

0

(Source: DfT Traffic Statistics Site number 78271)

People Powered CIC – www.people-powered.org.uk – info@people-powered.org.uk

 References
1

Cabinet Committee Report: Newport Strategic Junction Improvements, Appendix 3, WYG Junction
Performance Analysis. 13th September 2018.
2
Isle of Wight Council/WYG. Isle of Wight Junction Assessment and Design, Junction Feasibility Study:
Junctions 2-5 (Newport). August 2018.
3
Office for National Statistics. http://www.nomisweb.co.uk
4
Clark, C. An investigation into TEMPro growth factors Conference paper. 2016.
5
Melia, S. Proof of evidence of Dr Steve Melia in the matter of: Public Local Inquiry into the M4 Corridor
around Newport Project. February 2017.
6
Commission on Travel Demand. ALL CHANGE? The First Report of the Commission on Travel Demand The
future of travel demand and the implications for policy and planning. May 2018.
7
Isle of Wight Council/Mott MacDonald. Newport Traffic Model Data Collection, Model Validation and
Forecasting Report. January 2008.
8
Department for Transport. Annual traffic be vehicle type in Isle of Wight 1993-2018.
9
Goodwin, P. Empirical evidence on induced traffic. Transportation Volume 23, Issue 1. February 1996.
10
Department for Transport/WSP. Latest evidence on induced travel demand: an evidence review. May 2018.
11
CPRE. The end of the road? Challenging the road-building consensus: Learning from previous road schemes
for a better future. March 2017.

People Powered CIC – www.people-powered.org.uk – info@people-powered.org.uk