2 Demand
18. The DfT uses the National Transport
Model (NTM) to predict future traffic levels on the road network.
The NTM provides information to build the business case behind
strategic road schemes. The validity of the NTM's outputs and
how or whether they should be used in planning changes to the
SRN are a matter of great contention between supporters and opponents
of increasing capacity on our road network.
Demand modelling
19. The NTM indicates that traffic levels
will rise by 46% by 2040, as a result of population growth, economic
growth and a fall in the cost of fuel. The model shows congestion
on the road network increasing dramatically if no capacity is
added to it.[38] The
Chartered Institute of Logistics and Transport (CILT) told us
that the forecasts were "generally convincing".[39]
The AA added that it did not "dispute the figures, because
they are the best shot; I do not think they will ever be bang
on, but they have not been far off."[40]
20. Critics of the policies in Action
for roads rejected or questioned the outcomes of the forecasts.
The Cyclists' Touring Club (CTC) felt that cycling was under-represented:
We gave a specific example of how
we feel the national transport model is pretty flawed, in that
at the moment it is forecasting a drop in cycling between now
and 2035, despite the fact that cycling has increased by 23% in
the last five or six years and is clearly on an upward trajectory.
We think the model is a blunt tool; it is using very unsophisticated
ways of dealing with technological and social change, which is
a lot of what is driving the changes in transport at the moment.[41]
The Campaign for Better Transport (CBT)
noted that the DfT's model had overestimated traffic growth in
1989, 1997 and 2009.[42]
It argued that those overestimates had restricted economic development:
We would argue that the Department
for Transport has been overestimating traffic growth for 20 years.
That gives artificial barriers to development and the transport
infrastructure that goes with it, because the argument [to a developer]
is, "There will be all this traffic growth [from your development],
and you have to meet that"… The forecasts and modelling
that it is required that local authorities and developers take
up are based on flimsy foundations.[43]
21. The DfT stated to POST that the
NTM takes into account "a wide range of explanatory factors
for the level of road traffic, including congestion levels, demographic
changes, manufacturing growth, as well as availability and cost
of alternative modes of transport."[44]
However, the DfT admitted to us recently that the NTM has failed
to predict changes in traffic levels in London.[45]
We heard concerns that the DfT does not make available the assumptions
and methodologies underpinning the NTM in sufficient detail to
enable a thorough and independent assessment to be undertaken.[46]
By contrast, HM Treasury and the Office of Budget Responsibility
are committed to making their macroeconomic forecasts and methods
as transparent as possible.[47]The
DfT must immediately open the NTM to wider scrutiny, as the Treasury
and the OBR have done with their macroeconomic model, to ensure
that it accords due weight to all factors affecting transport
demand, including economic growth, industrial development, fuel
prices, vehicle ownership and demographic shifts.
Traffic volume
22. Traffic volume on strategic roads
peaked in 2006, fell between 2007 and 2010 and started slowly
to increase again in 2011.[48]
That is important evidence in the debate between those who argue
that the level of traffic has now peaked and those who support
the DfT's analysis that traffic volume decreased as a result of
the recession and began to increase again as the economy recovered.
One argument against 'peak car' is the suggestion that traffic
volume fell as a consequence of both the recession and the increased
cost of fuel.[49] The
newly published data show traffic volume falling before the recession
started in 2008, which decouples the recession from the decline
in road traffic volume.[50]
This fall in traffic volume also contrasts with the number of
rail journeys, which rose consistently per year throughout the
recession, despite rail fares increasing more quickly than fuel
prices.[51]
23. We heard that guidance on planning
and parking charges, such as that in Planning Policy Guidance
13 (PPG13), is another factor that influences the volume of road
traffic.[52]The PPG13
transport guidance was introduced in 2001. It was developed as
part of A New Deal for Transport. On planning, it promoted
development in urban, brownfield sites and discouraged greenfield
developments that were only accessible by motor vehicle.[53]
On parking, it required local authorities to set charges to encourage
the use of other forms of transport.[54]
Under PPG 13, the NTM road traffic forecasts are based on population
projections from the Office of National Statistics in 2008. Those
projections state that they "do not take into account any
future policy changes that have not yet occurred".[55]
24. The Department for Communities and
Local Government withdrew PPG13 in 2011, as part of a simplification
of planning rules.[56]
This recent change in planning and parking policy may well have
influenced traffic growth, both from new greenfield housing developments
and because driving into towns has become less expensive.[57]
25. Many witnesses to our inquiry discussed
the limitations of the DfT forecasts.[58]
POST stated:
The DfT's forecasts assume no change
in Government policy beyond that already announced. However, researchers
have stressed that car use will be shaped by future policies around
land use planning and measures to reduce driving, including the
viability of alternative modes of transport.[59]
Oxera also noted that the NTM does not
account for changes in the availability of parking:
A potential weakness of the NTM
is that it does not factor in constraints on the availability
of parking spaces. Decisions on whether to make a car journey
are likely to be heavily influenced by the ability to park at
a destination. Consequently, better understanding is needed of
how the availability of parking spaces will affect future road
demand.[60]
Given that it is impossible accurately
to predict local and national planning policy, demographics, types
of industry and the extent to which people will want to live in
urban areas, a road strategy based on forecast future growth in
traffic seems questionable.[61]
26. The DfT argued that its forecasting
was credible. It stated that past failures to predict the level
of traffic growth were the result of events that could not have
been predicted by the model:
…uncertainty is inherently
part of forecasting and predicting future behaviour and trends.
Traffic trends and outcomes depend on a large number of variables,
economic (GDP, oil prices) and behavioural.[62]
The Minister defended the NTM and its
use in strategic roads policy development:
The forecast is one that I am prepared
to defend, but it is dependent on some factors that are more difficult
to predict. It would be irresponsible of any Government not to
use these figures, which are the best, and the National Transport
Model, which is designed to forecast long-term trends.[63]
27. The DfT must develop a transparent
system of road planning as part of a wider national transport
strategy. This system should take into account demographic, economic
and land use changes, including changes in the location of homes
and parking policy. This will allow the DfT to select the most
resilient options for reducing congestion or improving connectivity
and to promote them across Government Departments and local authorities.
38 Department for Transport, Action for Roads: a network for the 21st century,
Cm 8679, July 2013 Back
39
SRN 47 Back
40
Q 124 [Mr Watters] Back
41
Q 126 [Mr Peck] Back
42
SRN 28 Back
43
Q 115 [Mr Joseph] Back
44
Peak car use in Britain, Parliamentary Office of Science
and Technology, November 2013 Back
45
Oral evidence taken before the Transport Committee on 31 March
2014, HC (2013-14) 1135, Q 92 and Q 104 [Mr Dowie] Back
46
SRN 6, SRN 9, SRN 26, SRN 29, SRN 42 Back
47
Office of Budget Responsibility, Memorandum of Understanding between the Office of Budget Responsibility and HM Treasury - the macroeconomic model,
2011 Back
48
Highways Agency, Post Opening Project Evaluation of Major Schemes Meta-analysis 2013: Main Report,
March 2014, p.55 Back
49
SRN 52, Q 124 [Mr Watters] Back
50
Highways Agency, Post Opening Project Evaluation of Major Schemes Meta-analysis 2013: Main Report,
March 2014 Back
51
Peak car use in Britain, Parliamentary Office of Science
and Technology, November 2013, SRN 23, SRN 26, SRN 42 Back
52
SRN 9, SRN 22 Back
53
Office of the Deputy Prime Minister, Planning Policy Guidance 13: Transport,
March 2001. Back
54
"Pickles and Hammond to end the war on motorists", Department
for Communities and Local Government press release, 3 January
2011. Back
55
SRN 9; Highways Agency, Post Opening Project Evaluation of Major Schemes Meta-analysis 2013: Main Report,
March 2014, p.55; SRN 22 Back
56
"Pickles and Hammond to end the war on motorists", Department
for Communities and Local Government press release, 3 January
2011 Back
57
Office of the Deputy Prime Minister, Planning Policy Guidance 13: Transport,
March 2001; SRN 9, WSP & Arup, Impacts of land use planning policy on transport demand and congestion,
(Cambridge, 2005) Back
58
SRN 6, SRN 9, SRN 16, SRN 28, SRN 42, WSP & Arup, Impacts of land use planning policy on transport demand and congestion,
(Cambridge, 2005) Back
59
Peak car use in Britain, Parliamentary Office of Science
and Technology, November 2013 Back
60
SRN 15 Back
61
SRN 9 Back
62
SRN 8 Back
63
Q 256 [Mr Goodwill] Back
|
