Policy instruments (3) - Transport Policy and Planning in Great Britain - page 235

development proposals involve weighing up a number of different objectives and may
require trade-offs to be made in order to arrive at a decision (e.g. between promoting
economic activity and safeguarding the environment). This means there is often room
for manoeuvre in relation to particular sites (which developers and others will seek to
exploit) whilst still being able to claim conformity with the development plan.
Under the 2001 revision of PPG13, development proposals with significant
transport implications are required to prepare and submit a 'Transport Assessment'
(TA) along with their planning application. This replaces the narrower Traffic Impact
Assessments (TIAs) required previously. TAs supply information on the accessibility
of the site by different modes and the likely modal split of journeys to and from it. In
addition they should identify the scope for improving access by non-car modes, for
reducing parking requirements and for mitigating transport impacts. (Guidance on
the preparation of Transport Assessments has since been published - see Box 14.3.)
Evidence from a TA forms the basis of negotiations with the developer in determining
the amount of parking to be provided (in the context of the policies contained in
the development plan), the nature and scale of any planning obligations and the
preparation of a Travel Plan designed to bring about desired travel outcomes (16.5).
In the case of development affecting trunk roads the Department has made it clear
that
developers can no longer expect that all the traffic they might produce will be
allowed without constraint. This would lead to ever-increasing congestion, which
poses a threat to economic growth and the environment.
(DfT 2007h para 27)
Developers are therefore required to consult with the Highways Agency about the
operational capacity of a trunk road affected by a proposal and how this compares
with the forecast traffic demand during a period ten years after the registration of a
planning application. (This forecast includes existing demand plus forecast general
traffic growth, demand likely to be generated by development commitments in the area
and demand from the proposed development net of any reduction obtained through
the TA procedure.) Where the operational capacity of the road will be exceeded,
capacity improvements may be agreed, normally at the developer's expense, subject
to environmental and deliverability considerations. The aim of this is to ensure that
traffic conditions on the trunk road throughout the period are no worse than if the
development had not taken place.
In areas within and surrounding centres where on-street parking is controlled, a
key factor influencing the volume of attracted traffic is the amount of private non-
residential (PNR) space available. In 1994 government policy switched from requiring
planning authorities to set minimum standards of provision (originally intended to
reduce the demand for on-street space) to setting maximum standards (as a demand-
management tool). This was complemented later by publication of (undemanding)
national maximum standards for different classes of non-residential development and
inviting regional planning bodies and local planning authorities to adopt more rigorous
standards 'where appropriate':
Reducing the amount of parking space in new development (and in the expansion
and change of use in existing development) is essential as part of a package of
planning and transport measures to promote sustainable travel choices…