Wellington traffic light control data and traffic flow statistics

Martin Krafft made this Official Information request to Wellington City Council

The request was partially successful.

From: Martin Krafft

Dear Wellington City Council,

Please provide the data controlling all traffic lights in the Wellington CBD, such as timings, interdependencies, and other rules, using a standard file format, including adequate documentation to be able to make sense of them.

Please also provide aggregated statistics regarding the flow rates across the main arteries of town at different times of the day, again, using an accessible format.

If you could also provide the data for SH1 between Wellington and Upper Hutt, that would be helpful, too. Or do I have to approach Regional Council about that?

Most of the time, driving in Wellington means stopping at every second red light, when in very rare cases, it's actually possible to drive across town on a "green wave".

As I am sure you're aware, breaking releases microparticules, and accelerating pumps excessive exhaust into the air, so optimising the flow across town would be beneficial for the environment, increase the standard of living for everyone, and save drivers real money.

I'd like to understand, how this comes to be, study the patterns, and using a simulator, maybe be able to suggest improvements.

Yours faithfully,

Martin Krafft

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From: BUS: Assurance
Wellington City Council

Hello Martin,

Thank you for your information request, submitted through the FYI.org.nz website, with the questions concerning the traffic light control data, and traffic flow statistics.

This has been logged by the Council's Assurance team, with the unique identifier IRO-10444, and we will look into the question you raised.

Under LGOIMA, we are required to provide you with a decision on your request within 20 working days - by 23 September 2020 - but will respond to you sooner if practicable to do so.

Kind regards

Chris
Chris Brown | Acting T/L | Complaints & Information Assurance | Wellington City Council
P 04 803 8368
E [email address] | W Wellington.govt.nz | |

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From: Martin Krafft

Dear BUS: Assurance,

Your reply is overdue. As I am sure you are busy with lots of stuff, it would be helpful if you could advise with an ETA.

Yours sincerely,

Martin Krafft

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From: BUS: Assurance
Wellington City Council

Hello Mr Krafft,

Please accept my apologies.

I will chase this up for you.

Kind regards

Chris

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From: BUS: Assurance
Wellington City Council


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Hello Mr Krafft,
please accept my apologies for the delay in getting this to you.
The Council team who look after the systems have provided the following
for you - 

Q1. Please provide the data controlling all traffic lights in the
Wellington CBD, such as timings, interdependencies, and other rules, using
a standard file format, including adequate documentation to be able to
make sense of them.

 

A1. We are unable to release the above data, timings and other
documentation as it would raise operational and security risks for NZTA’s
and WCC’s transport network. Releasing explanatory documentation such as
User Manuals would also breach our licence agreement with the software
supplier Transport for New South Wales.

 

The signals in Wellington are controlled using a software package called
SCATS. This package is widely used in Australasia. More information about
SCATS can be found on the following
website. [1]https://www.scats.com.au/homepage/scats-...

 

Q2. Please also provide aggregated statistics regarding the flow rates
across the main arteries of town at different times of the day, again,
using an accessible format.

 

A2. We attach files showing 15 minute volumes of vehicle traffic using
Karo Dr and Vivian St. Volumes shown are for the through lanes combined
and do not include turning lanes.

 

Q3. If you could also provide the data for SH1 between Wellington and
Upper Hutt, that would be helpful, too. Or do I have to approach Regional
Council about that?

 

A3. We do not possess this data. We suggest you contact NZTA for this
information since they operate that part of the State Highway network.

 

General:

Green waves (coordination) are one useful component of a wider traffic
signal control strategy but are not used on every intersection approach.
Coordination is used on major routes such as the Waterfront and SH1
(Vivian St and Karo Drive). Green waves are monitored using Time Distance
Diagrams such as the one shown below for Karo Dr & Vivian St.

 

 

If you have any questions, please come back to me
Kind regards
Chris

Chris Brown | Acting T/L | Complaints & Information Assurance |
Wellington City Council
P 04 803 8368
E [2][email address] | W [3]Wellington.govt.nz 

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If you are not the intended recipient, you are asked to respect that
confidentiality and not disclose, copy or make use of its contents.
If received in error you are asked to destroy this email and contact the
sender immediately. Your assistance is appreciated. 

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From: Martin Krafft

Dear BUS: Assurance,

Thanks for your response, which I find to be lacking. What is the point of the OIA, when information seems to be withheld by default under the pretense that it'd be a security (or often privacy) issue to release them?

Can you please elaborate on what "operational and security risks" there would be in releasing the timing data?

How do you expect citizens to engage when the data are not made available?

Why are "green waves" not used at every intersection? What criteria are being applied to decide which intersections should be coordinated?

Yours sincerely,

Martin Krafft

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Tony Randle left an annotation ()

I know it's frustrating but it might be more helpful to reply by asking the WCC to provide the specific reason under LGOIMA for refusing to provide the requested information and the the grounds supporting that reason (which is something they have to tell you). See Page 18 of Making an Official Information Request Guide:
https://www.ombudsman.parliament.nz/reso...

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From: Martin Krafft

Dear BUS: Assurance,

I've been advised by various 3rd parties to as you for the LGOIMA refusal reason.

Alternatively, if it helped, maybe we should have a brief phone call or meeting, so that I can explain to you what I intend to do, and why that doesn't present a security risk?

Yours sincerely,

Martin Krafft

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From: Ian Hunter
Wellington City Council


Attachment 20201019.lx.txt
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Dear Mr Krafft,

 

Thank you for your email to the Council dated 11 October 2020, in respect
of your request for traffic signal data, and why ‘green waves’ are not
used at every intersection.

 

The Council has reviewed its position in respect of the traffic signal
data and the SCATS configuration (timing) data is attached.

 

As advised in the Council’s response dated 8 October 2020, we are unable
to reproduce or provide you with a copy of the SCATS user manuals as the
Council does not own the copyright of this information.

 

However; should you wish the view a copy of the user manuals we can
arrange a mutually convenient time to facilitate this. Please advise if
you would like to progress this option.

 

With respect to why ‘green waves’ are not used at every intersection and
what criteria are being applied to decide which intersections should be
coordinated, the following criteria are considered:

 

o The route is a main thoroughfare, usually with more than one through
lane in the direction being coordinated eg. Waterloo Quay.
o Vehicle volumes are high eg. during peak times
o Platoons of vehicles are likely to remain intact from intersection to
intersection
o Additional delays to pedestrians, vehicle occupants, cyclists and
public transport patrons using the uncoordinated phases are
acceptable.

 

Should you have any further questions please contact me.

 

Kind regards,

Ian

 

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