Work is starting downstream of the CNC – how were the designs decided?

Update: I’ve been closely following the issues around the Christchurch Northern Corridor (CNC) for some time now. The motorway is due to open ‘mid 2020’, and work is getting underway in the St Albans, Edgeware, and Mairehau areas to to manage the expected downstream increase in traffic.  This article recaps the Christchurch City Council’s consultation and decision-making processes over the past two years.

DEMP consultation leaflet 1
The leaflet from the first of three rounds of consultation

The Downstream Effects Management Plan (DEMP) was commissioned by the Christchurch City Council to identify and address downstream effects of the CNC.

For more background information and further links see this previous article: Council settles on solution for CNC traffic south of Berwick Street.

An initial round of consultation in April-June 2018 captured feedback which was passed on to the independent traffic expert working on the DEMP. Following publication of the draft DEMP the Council went back to community a second time with more detailed proposals, and then a third consultation took place between the DEMP being finalised and decisions being made by the Council in September 2019.



DEMP timeline Feb 2020
A summary of key milestones in the process to decide the management of traffic impacts of the Christchurch Northern Corridor (CNC)

Was there authentic consultation?

In my view an authentic consultation is one where there is good information provided, good public response, and where the Council is open to changing plans based on that response. In the case of the DEMP, the public response was high (hundreds of responses in each of the three rounds), and parts of the plan have changed substantially.

final can the plan small
Protest signs outside Council ahead of the final decision on the DEMP in September 2019

The final plan runs to 150 pages, and the resolutions passed by the Council in September 2019 fill 75 pages of the meeting’s agenda (web link, see item 9). The table below is a high-level summary that shows how some selected aspects of the DEMP have evolved over time:

Stage Proposal/decision
Traffic management south of Berwick Street
Pre DEMP 3-laning Barbadoes & Madras/Forfar streets
Draft DEMP Options including the 3-laning above, making Madras/Barbadoes one way all the way to Warrington St, or 4-laning Sherborne St
Final DEMP 2 lanes southbound on Sherborne in the morning peak,1 lane northbound at all times
Council decision Sherborne St to remain 1 lane each way with some changes to intersections
Traffic calming*
Pre DEMP “To discourage short cuts through side streets and improve safety there are a number of options…”
Draft DEMP Calming to 3 streets prior to CNC opening, 6 more streets within three years, plus safer cycling routes / greenways
Final DEMP Calming to 6 streets prior to CNC opening, 3 more streets within three years, plus safer cycling routes / greenways
Council decision Follows DEMP recommendations.
“Notes that that Council staff will further engage with residents of streets including Mersey Street, Severn Street, Thames Street, Nancy Avenue, Kensington Avenue, Flockton Street and Francis Avenue to develop proposed traffic calming solutions for the streets. These proposals will be reported back to the Community Board and Council for approval to proceed to detailed design and construction.
Notes that that Council staff will engage with communities affected by the proposed turning restrictions at Knowles Street, Weston and McFaddens Roads to ensure the implications of any potential turning restrictions are fully understood. These proposals will be reported back to the Community Board and Council for approval to proceed to detailed design and construction.”
Clearways (Cranford Street south of Innes Road)
Pre DEMP Peak hour clearways between Innes Road and Berwick Street
Draft DEMP As above
Final DEMP As above
Council decision “…the clearways are not resolved at this stage with a view to considering the implementation of Travel Demand Management to address traffic volume concerns…”
Travel Demand Management (TDM)
Pre DEMP Not mentioned.
Draft DEMP “The Plan supports further travel demand management initiatives in northern Christchurch and beyond, … However, the focus of the Plan … is to mitigate the impacts of the additional traffic that will enter the local network at Cranford Street”
Final DEMP “…the report recommends that Council investigate whether much of the additional road capacity … (eg the peak period clearways) can be restricted to high occupancy vehicles (HOV), including busses only when first opened. The use of HOV lanes better aligns with the community who want a reduction in vhicles and more people on busses through St Albans.”
Council decision “Request staff work with the strategic partners … to deliver a package of Travel Demand Management measures…” and ‘Request that staff investigate and report back on: park & ride; pricing mechanisms; peak-time Public Transport lanes on Cranford/Sherborne.’
Speed zones
Pre DEMP Limited number of “potential streets for speed reduction measures”
Draft DEMP Nine 30km/h (or 40km/h) reduced speed limit areas
Final DEMP Fifteen 40km/h zones, one 30km/h zone
Council decision As per final DEMP

* much of the scope of the DEMP can be considered traffic calming, which makes it tricky to summarise for this article – here the term can include turning restrictions at intersections, narrowing, landscaping, raised platforms, safer cycling routes / greenways…

What now?

In September 2019 the Council approved the detailed design and construction of downstream effects projects. A Newsline artcle and start work notices have been published recently, announcing the commencement of these works. Copies of the Council’s start work notices are delivered locally to areas impacted by roading projects, and the content is also published on the ‘work in your area‘ section of the Council’s website. I’m currently testing an online archive of work notices relevant to the Papanui-Innes area in PDF format (feedback is welcome).

There’ll also be further consultation on some specific traffic calming measures, as noted in the table above.

Question for readers

What do you think about the Council’s processes around the management of impacts downstream of the CNC – in particular the multiple rounds of consultation, and the solutions that have been reached?

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