50 Victoria Street
Private Bag 6995
Wellington 6141
New Zealand
16 July 2018
T 64 4 894 5400
F 64 4 894 6100
www.nzta.govt.nz
Tom Atkinson
[FYI request #7881 email]
REF: OIA-3843
Dear Tom
Request made under the Official Information Act 1982
Thank you for your email of 21 May 2018 requesting raw data concerning motorway on-ramps under
the Official Information Act 1982 (the Act). Your original request is attached for reference.
Your request has been refused under section 9(2)(ba)(i) of the Act, in order to protect information
which is subject to an obligation of confidence and where making the information available would be
likely to prejudice the supply of similar information, or information from the same source.
While the NZ Transport Agency holds raw data relating to motorway on-ramp signals, it is provided to
the Transport Agency by an external supplier. Under the terms of agreement with the supplier, the
Transport Agency has been provided with the raw data for internal use only. Further, the Transport
Agency is not entitled to release the raw data to an external third party without direct permission from
the supplier. The supplier has confirmed that any recipient cannot have access to this data for their
own purpose. In order to release the data, the reason would have to be shown to be providing
assistance to a Licensee; for example, software hosting. In this case, your request does not fall under
this criteria.
As it is in the public interest that such information should continue to be supplied, I do not consider
there are any other factors which would render it desirable, in the public interest, to make the
information available.
Under section 28 of the Act, you have the right to ask the Ombudsman to review my decision to
withhold this information. The contact details for the Ombudsman can be located at
www.ombudsman.parliament.nz.
In order to provide reasonable assistance, please find some general information below in regards to
the conditions which trigger on-ramp signals to activate and deactivate each day.
The ramp signals have a multitude of parameters that allow switch on, switch off and red time control
(the length of time the red light on the signal is operating). The Auckland Motorway network is covered
by thousands of vehicle loop detectors to measure the flow (number of vehicles) and occupancy
(density of vehicles) at critical locations. These sensors feed these live traffic conditions back to the
system. The system analyses the information and makes a decision as to which ramps need to be
activated. More than one set of ramps can be activated and work together to help manage traffic.
The ramp signals can operate any time between 5:30am and 8pm on weekdays. The system will force
the signals to be off at all other times, unless the command is overridden by an operator.
When the flow or occupancy of traffic in one area of the motorway is approaching a critical level, the
ramp signals switch on to manage the demand of traffic from the on-ramps. If the flows and
occupancies continue to rise, the system automatically adjusts the red times to suit. Calculations for
this occur every 10 seconds.
Each on-ramp also has safeguards set in place, whereby multiple vehicle sensors detect critical levels
of occupancy. If this occurs, the red times calculated will be overridden in order to limit the effects of
on-ramp queuing. However, if the mainline motorway conditions become severely congested, these
overrides are automatically disabled until the motorway traffic flows recover. Operators can override
any red time setting, switch on or switch off command when required.
Ramp signals are widely used internationally and have been shown to reduce congestion and improve
traffic flows. This results in more consistent travel times, safer merging and fewer accidents. While the
Transport Agency endeavours to provide people-centred services, it would be implausible to disable
the on-ramp signals within the Auckland transport network, due to consequential high impact and
safety concerns.
More information regarding ramp signals is available on our website at the following link:
https://nzta.govt.nz/roads-and-rail/ramp-signals/.
If you would like to discuss this reply with the Transport Agency, please contact Tania Barnett, Senior
Customer Access Representative, by email to [email address] or by phone on 0800 108
809.
Yours sincerely
Neil Walker
Senior Manager Journey Management Centre
