Research 350 - NZ Transport Agency

APPENDIX A
Appendix A: Additional Economic Benefits
from the Transmission Gully
Project
(Brown, Copeland & Company Limited, for Greater Wellington City
Council, Wellington, New Zealand, March, 2004)
AA.1
Synopsis
This paper reviews the appraisal mechanism for the Transmission Gully road project in
Wellington. The key focus is on whether any there are additional economic benefits (in
addition to the ‘traditional benefits of travel time savings, vehicle operating costs and
accident costs) arising from the completion of the project.
A number of sources of additional national or regional economic benefit are identified. Major
identified benefits include:
• Generated traffic – This will produce additional economic benefits from a national and
regional perspective. These are seen as significant in this case and should be included
as a part of the assessed benefits if they have not already been so.
• Local network traffic benefits – Access between Wellington CBD and the suburbs will
be improved by the project. These impacts should be addressed by the appraisal (if
they are not already).
• Hutt Valley traffic benefits – Effects for traffic to and from the Hutt Valley should be
included in the analysis as part of a full network analysis of benefits.
• Impacts of Abnormal Delays – The existence of an alternative route out of Wellington
will reduce the incidence of abnormal delays due to accidents or floods. These will not
be built into average travel times used by models, as these work on the basis of
observed times during typical AM inter-peak and PM periods. Allowance should be
made for this in any appraisal.
• Responses to unreliability of travel time – Abnormal delays, if frequent enough, can
cause motorists to change their behaviour patterns (e.g. travelling earlier/later than
necessary, working longer hours, travelling off-peak and over-investing in vehicles).
This economic cost will probably be ignored by a conventional SCBA and should be
allowed for in an assessment.
• Intangibles – These include environmental and social impacts.
Less significant national and regional benefits include:
• Ability to handle oversized or very heavy vehicles – This was seen as a longer term
benefit which might be quantified following additional studies.
• Wider catchment for job seekers and employers – An increase in workforce quality
could ensue from the route; however, this should only be treated qualitatively.
• Potential travel benefits – These include the utility residents and businesses get from
knowing a journey is possible, without necessarily making the journey. It is suggested
these could be estimated on a broad ‘willingness to pay’ basis.
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