50 Victoria Street
Private Bag 6995
64 4 894 5400
64 4 894 6100
28 May 2018
[FYI request #7738 email]
Dear Andrew Request made under the Official Information Act 1982
Thank you for your email of 30 April 2018 requesting the following information under the Official
Information Act 1982 (the Act):
…information about cost and benefits of the smart wel ington motorway project done in about
What I am wanting is to show costs and if they gave benefits as given in business case.
Forecast of cost before project start.
Total costs at end of project.
Any benefits predicted as in business case.
Any assessment of benefits seen after project.
Any documents that might help us understand why no traffic improvements after project.
Please find responses to each of your questions below:
1. The original approved cost for all phases of this projects was $55.85 million
2. The final cost of phases 1 to 3 of the project (including the Ngauranga emergency on-ramp) was
$81.38 mil ion
The project has been the subject of a number of scope changes and associated cost increases, hence
the difference in cost between the original approved cost and the final cost. The significant changes
• Extension of the smart motorway (ATMS - Active Traffic Management System) along SH2 towards
• Early delivery of the first section of the Petone to Ngauranga cycleway,
• The use of premium long life, low maintenance surfacing (Epoxy Modified OGPA – Open Graded
Porous Asphalt), and
• Additional surfacing works for maintenance purposes.
3. The fol owing BCRs (Benefit Cost Ratios) were confirmed in the SAR (Scheme Assessment Report –
pre Business Case process). Benefits included:
• Improved efficiency through journey time reliability.
• Reduced congestion.
• Safety improvements through reduced lane changing and smoother traffic flow.
• Environmental improvements, including upgraded drainage and stormwater management.
• Best use of existing assets including; optimal use of road shoulders rather than road widening
to facilitate four laning northbound from Aotea Quay to Ngauranga interchange, and reuse of
the redundant Thorndon Stub Bridge (rather than demolition and re-build) to enable bridge
widening for the four-laning.
Early works: SH1/2 merge and diverge improvements
Stage 1: SH2 Ngauranga northbound on-ramp capacity improvements
Stage 2: ATMS (Active Traffic Management System)
Stage 3: Four laning northbound from Aotea Quay to Ngauranga
Emergency on-ramp at Ngauranga
Stage 4: Four-laning southbound including Thorndon Overbridge
widening Full Scheme (excluding Early works)
4. BCRs have not been re-evaluated at this stage. However, performance assessments to date would
suggest the following benefits:
• Journey times have general y reduced for motorists travelling north from the CBD to
Johnsonvil e on State Highway 1.
• Overall variability in travel times through the smart motorway in 2017 is similar to 2014
despite the increase in traffic over this period.
• Southbound throughput of traffic on State Highways 1 and 2 has improved slightly due to
improved operation of the SH1/2 merge.
5. I have identified one document that fal s within this part of your request and is enclosed as
attachment 1. The document, titled Managed motorway (Smart Motorway) performance – July 2016
to June 2017, provides comparisons of travel times, travel time variability and throughput for each
month in the twelve month period since opening, with the corresponding month in 2014 (pre-
construction). It also provides an assessment of compliance with posted speed limits from April to
The Wel ington managed motorway opened on 22 June 2016 for northbound traffic, and on 8 July
2016 for southbound traffic.
If you would like to discuss this reply with the NZ Transport Agency, please contact Glen Prince,
Principal Project Manager, by email to [email address] or by phone on 04 931 8918.
Senior Manager, Project Deliver