Safer Speeds Cost Benefit Analysis
December 2021
Executive Summary
The Land Transport Rule: Setting of Speed Limits 2022 proposes a general lowering
of speed limits around schools to improve safety outcomes and make walking,
cycling, and scooting appealing modes of transport to and from school. Under the
proposed rule, 40% of speed limited changes would be required to be completed by
30 June 2024 and the remaining would have to be completed by 31 December 2029.
There are 81 schools and colleges within Wellington City, the large majority of which
will require a lowering of speed limits to meet the requirements set out in the rule.
This report outlines the results of a cost benefit analysis that was completed to
assess the costs and benefits of alternative approaches to delivering safer speeds
on Wellington’s streets. A total of 9 alternative approaches to delivering safer speeds
on Wellington’s streets have been developed to assess their relative costs and
benefits. These options vary across three parameters:
• the approach to safe speeds around schools (permanent or variable)
• the approach to safe speeds citywide (default urban speed limit of 30 km/h
(excluding arterials), 40 km/h (including arterials) or no change)
• the implementation timing (implemented by 2024 or 2030).
The cost benefit analysis includes detailed cost estimation, modelling of travel time
disbenefits using a mesoscopic traffic model in AIMSUN, and crash savings
estimation using Crash Analysis System data and Monetised Benefits and Costs
Manual procedures, assuming a 40-year analysis period.
Results indicate that implementing variable speed limits around schools provides the
lowest benefits and very low value for money, as compared to options that employ
an area-wide speed management approach or permanent lower speeds around
schools. This is because the crash reduction benefits are low because benefits are
only realised over a small proportion of the road network over a small proportion of
the day.
Lowering speeds around schools at all times would be somewhat more effective at
reducing deaths and serious injuries and is the option with the highest value for
money, due to relatively low costs and low travel time disbenefits.
However, full-time speed limit area setting is by far the most effective option at
reducing injuries, as around half of deaths and serious injuries occur in areas that
could benefit from slower speeds. A range of different options for reducing urban
speed limits have been considered in this analysis. The best performing option is
one that would see a speed limit of 30 km/h for local streets and speed limit of 40
km/h for arterial streets. This option would deliver substantial crash reduction
benefits of over $500 million, discounted over 40 years.
1
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Background: The Land Transport Rule: Setting of Speed Limits
2022
The Land Transport Rule: Setting of Speed Limits 2022 proposes a general lowering
of speed limits around schools to improve safety outcomes and make walking,
cycling, and scooting appealing modes of transport to and from school. Under the
proposed rule, road controlling authorities would be required to reduce speed limits
around:
• urban schools to 30 km/h (variable or permanent speed limits), with the option
of implementing 40 km/h speed limits if appropriate
• rural schools to a maximum of 60 km/h (variable or permanent speed limits)
Under the rule, 40% of speed limited changes around schools would have to be
completed by 2024 and the remaining would have to be completed by 2029. There
are 81 schools and colleges within Wellington City, the large majority of which will
require a lowering of speed limits to meet the requirements set out in the rule.
Safety and speed in Wellington City
Over the last 10 years (2010-2019), over 4000 injuries were reported a result of
crashes on Wellington’s urban road network. Road crashes resulted in 29 fatalities
(an average of around three per annum) and over 660 serious injuries. The total
social cost of road crashes over the 2010-2019 period is estimated at more than
$850 million.1
Road safety issues do not affect all transport users equally. As shown in
Table 1,
pedestrians and cyclists make up one third of injuries on the transport network; they
account for 30% of minor injuries, 45% of serious injuries, and 38% of fatal injuries
on Wellington’s roads.
Table 1: Reported people injured in road crashes, by severity and mode of travel
Vehicle
Severity
Pedestrian
Cyclist
Total
Occupant
Fatal
7 (24%)
4 (14%)
18 (62%)
29 (100%)
Serious Injured
152 (23%)
143 (22%)
367 (55%)
662 (100%)
Minor Injured
531 (16%)
482 (14%)
2,329 (70%)
3,342 (100%)
Total
690 (17%)
629 (16%)
2,714 (67%)
4,033 (100%)
The Council uses speed management as a key means of reducing harm on its
roads. From 2010-2016, the Council implemented safer speed zones across almost
1 These figures are based on an analysis of data from NZTA’s Crash Analysis System.
2
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all town centres in the city, and in 2020 it adopted a 30 km/h speed limit on most
central city streets. Elsewhere in the city, there is a default urban speed limit of 50
km/h, apart from the suburb of Newtown which has a 40 km/h speed limit, and a
small number of rural roads that have a speed limit of 60 km/h or 70 km/h.
Figure 1
and Figure 2 below show current registered speed limits across Wellington City.
Despite these recent speed limit changes, roughly 80% of Wellington roads have
speed limits that do not align with the safe and appropriate speed calculated for the
road. Of the roads that do not align with safe and appropriate speeds, 98% of them
demand a speed reduction while the rest are likely to work more efficiently with a
slightly higher speed.
Figure 1: Current registered speed limits in central Wellington City
3
Figure 2: Current registered speed limits in Wellington City
4
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Purpose of this report
This report outlines the results of a cost benefit analysis that was completed to
assess the costs and benefits of alternative approaches to delivering safer speeds
on Wellington City’s roads.
The options considered have been developed in the context of the following
objectives:
• achieving compliance with the requirement to reduce traffic speed around
schools, 40% by 2024 and the remainder by 2029;
• reducing deaths and serious injuries across the Wellington transport network;
• making walking cycling, and scooting more appealing modes of transport for
all journeys, including to and from school; and
• providing value for money for our community and our ratepayers.
Options assessed
A total of 9 options for delivering safer speeds on Wellington City’s roads have been
developed to assess their relative costs and benefits. These options vary across
three parameters:
• the approach to safe speeds around schools (permanent or variable)
• the approach to safe speeds citywide (default urban speed limit of 30 km/h
(excluding arterials), 40 km/h (including arterials) or no change)
• the implementation timing (implemented between 2024 and 2030)
The alternative approaches used across the 9 options are set out in
Table 2 and
Note: Option 4 (30 km/h speed limit) excludes most arterial roads (which remain at 50 km/h)
whereas Option 3 (40 km/h) reduces the traffic speed limit on most arterial roads to 40 km/h.
Table 3 below. Maps outlining the geographic extent of each option are shown in the
Appendix.
5
Table 2: Summary of options assessed
Option
Intervention
Timing
Variable 30 km/h speed limits outside
40% of urban schools by
1a: Variable at
urban schools; no changes elsewhere
June 2024, all remaining
schools
schools by December
2029
1b: Variable at
Variable 30 km/h speed limits outside
All schools by June 2024
schools
urban schools; no changes elsewhere
(accelerated)
Permanent 30 km/h speed limits
40% of urban schools by
2a: Permanent at outside urban schools; no changes
June 2024, all remaining
schools
elsewhere
schools by December
2029
2b: Permanent at Permanent 30 km/h speed limits
All schools by June 2024
schools
outside urban schools; no changes
(accelerated)
elsewhere
Default urban speed limit of 40 km/h
Implemented by June
for almost all streets (with exceptions
2024
3: 40 km/h
for a small number of arterials, and all
default
regional, national and high volume
roads remaining at 50 km/h)
Default urban speed limit of 30 km/h
Implemented by June
for most streets (with exceptions for
2024
4: 30 km/h
most arterials and all regional,
default
national, and high volume roads
remaining at 50 km/h)
Variable 30 km/h speed limits outside
40% of schools
5a: 40 km/h
urban schools, followed by citywide
implemented by June
default + variable speed limit review (default 40 km/h)
2024, all remaining by
at schools
December 2026, citywide
implemented by 2028
5b: 40 km/h
Variable 30km/h speed limits outside
All schools implemented
default + variable urban schools, followed by citywide
by June 2024, citywide
at schools
speed limit review (default 40 km/h)
implemented by 2025
(accelerated)
Speed limit of 30 km/h for non-arterial
Implemented by June
streets and speed limit of 40 km/h for
2024
6: 40/30 km/h mix
arterial streets (with exceptions for a
few arterials, regional, national, high
volume roads remaining at 50 km/h)
Note: Option 4 (30 km/h speed limit) excludes most arterial roads (which remain at 50 km/h) whereas
Option 3 (40 km/h) reduces the traffic speed limit on most arterial roads to 40 km/h.
6
Table 3: Comparison of approaches across options
Approach at schools
Variable safe speeds Permanent safe speeds
Variable at schools
Permanent at schools
50 km/h (no change)
(Option 1a, Option 1b)
(Option 2a, Option 2b)
dei
40 km/h default +
ywt
40 km/h (except regional,
40 km/h default
variable at schools
national, & high volume)
(Option 3)
h ci
(Option 5a, Option 5b)
roac
30 km/h default
pp
30 km/h (except arterial, regional,
(Option 4)
A
national & high volume)
40/30 km/h mix
(Option 6)
Travel time impact assessment
A traffic modelling assessment has been undertaken to assess the likely impact of
each of the nine options on delays for people travelling in motorised vehicles in
Wellington City.
Modelling was undertaken using recognised transportation modelling suite (AIMSUN
software). The Wellington AIMSUN model covers all major roads of Wellington
region south of Ngauranga Gorge as shown in the image below.
7
Figure 3: Wellington AIMSUN Model Coverage
The model consists of three peaks: morning peak (6 am – 10 am), interpeak (10 am
– 2 pm) and the afternoon peak (3 pm – 7 pm).
An off-peak model was created for this analysis to assess the impact of speed
reduction, as speed limit reductions are likely to have a higher impact on travel times
when traffic volumes are lower. The off-peak model represents traffic conditions
during night-time, when the traffic on the road can drive at the speed limit of the
road, if the road environment allows. To create an off-peak model the traffic volume
of the morning peak was reduced to half for a duration of 4 hours.
The modelling was carried out at the mesoscopic level, which is the second most
detailed level of analysis. The speed limits of roads were changed based on the
scenario being modelled and the effect of speed reduction was observed on total
travel times.
The modelling undertaken has not assumed any change in vehicle travel patterns, in
terms of either volumes or distribution of trips across time periods, due to the speed
limit changes. Urban speed limit changes are typically designed to help encourage
more walking and cycling, so it is reasonable to assume that the changes would
8
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result in an increase in number of walking and cycling trips and a reduction in driving
trips for shorter trips. However, the magnitude of this mode shift is difficult to
quantify, so it has been excluded from the analysis. Because mode shift would
produce travel time benefits which would offset travel time disbenefits from lower
average traffic speeds, the economic assessment represents a conservative
estimate of the benefits of speed limit changes.
The base scenario models the speed limits of the road as the current speed limit.
The scenarios for 40 km/h on roads except certain roads and 30 km/h on roads
except certain roads modify the speed of a road in the model accordingly.
Option 6 (40/30 km/h mix) has not been directly modelled as it was added as an
option after the modelling phase. The travel time disbenefits are assumed to be
halfway between Option 3 (40 km/h default) and Option 4 (30 km/h default).
A default urban speed limit of 40 km/h (with exceptions for selected roads) is
estimated to increase travel times by around 5% during the morning peak, while a
default urban speed limit of 30 km/h (with exceptions for selected roads) is estimated
to increase travel times by around 6% during the morning peak. This would be a
result of most of the travel happening on the part of the network that is not affected
by speed limit changes. Effects of lower speeds on travel times are heterogeneous
across the city. Slower speed limits actually reduce travel times on busy sections of
the network with high traffic signal density, where they moderate arrivals and
reducing queuing at traffic signals. Slower speeds slightly increase travel times in
areas of the network with less congestion and fewer traffic signals, where speed
limits have a larger effect on journey times.
For speed limit reductions around schools, projected increases in travel time have
been estimated by scaling the citywide impacts according to the share of the network
that would be impacted by the changes around schools. It is assumed that each of
the 81 schools would have an average of 600 metres of slow speed streets around it,
resulting in speed reductions on 48.6 kilometres of road centreline network in total.
This represents 7% of Wellington’s total road centreline network. Therefore, it is
assumed that reduced speed limits around schools would be associated with a travel
time increase that is 7% of the effect of reducing speeds on a citywide basis.
Modelling has assumed that the speed limit has been reduced in the treatment areas
but there have not been other substantial changes that may increase compliance,
such as traffic calming measures and increased enforcement. This may represent a
small underestimate of travel time disbenefits.
While the modelling undertaken has changed the speed limit on roads, AIMSUN
does not assume universal compliance with speed limits. Instead, it employs detailed
modelling of the behaviour of individual vehicles assuming that driver behaviour is
dependent on local conditions, such as speed limits, road type, traffic volumes, and
differences in safe stopping distances and maximum speeds across vehicle types.
Table 4 shows the speed acceptance parameters used in the AIMSUN modelling
and Figure 4 shows the distribution of vehicles on streets with a 50 km/h speed limit.
With a 50 km/h speed limit, it is assumed that 90% of vehicles travel at or below the
speed limit and 10% of vehicles travel above the speed limit.
9
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Table 4: Speed Acceptance Parameters in AIMSUN
AIMSUN Speed Variable
Parameter
Mean
0.90
Deviation
0.10
Minimum
0.70
Maximum
1.10
Figure 4: AIMSUN Speed Distribution at 50 km/h Speed Limit
Travelling at or below speed limit
Travelling above speed limit
10%
n
9%
evig 8%
at gn 7%
ille
6%
av
tr
d
e
s
e 5%
elci sp 4%
f veh
3%
o
t
n
2%
ec
1%
Per
0%
33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57
Operating speed (km/h)
10
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Table 5 below outlines the estimated percentage increase in travel time for all
motorised vehicle travel in Wellington City due to speed limit changes. For the
options that include variable speed limits outside schools, it has been assumed that
travel time disbenefits occur during half the period of the AM-peak and PM-peak
periods, representing two hours in the morning and two hours in the afternoon.
11
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Table 5: Projected increase in travel time across Wellington City by option
Projected increase in travel time across
Option
Wellington City (%)
Off-peak
AM-peak
Inter-peak
PM-peak
1a: Variable at schools
0%
0.4%
0%
0.2%
1b: Variable at schools
0%
0.4%
0%
0.2%
(accelerated)
2a: Permanent at schools
0.4%
0.4%
0.4%
0.2%
2b: Permanent at schools
0.4%
0.4%
0.4%
0.2%
(accelerated)
3: 40 km/h default
4.5%
4.9%
4.8%
1.7%
4: 30 km/h default
6.4%
5.7%
6.1%
2.2%
5a: Variable at schools,
4.5%
5.0%
4.8%
1.7%
40km/h default (weighted
network impact)
5a: Variable 30km/h outside
0%
0.4%
0%
0.2%
schools component
5a: 40 km/h city component
4.5%
4.9%
4.8%
1.7%
5b: Variable at schools, 40
4.5%
5.0%
4.8%
1.7%
km/h default (accelerated)
(weighted network impact)
5b: Variable 30km/h outside
0%
0.4%
0%
0.2%
schools component
5b: 40 km/h city component
4.5%
4.9%
4.8%
1.7%
6: 40/30 km/h mix
5.5%
5.3%
5.5%
2.0%
Table 6 below outlines the process used to calculate travel time disbenefits per hour.
A composite value of time for each of the four time periods modelled was calculated
using two inputs: value of time by trip purpose, and the proportion of trips by purpose
in each time period. The proportion of trips by travel purpose is based on analysis of
Household Travel Survey data from 2015-2017 for trips with a destination in
Wellington City by mode of travel. Value of time by trip purpose was derived from the
Monetised Benefits and Costs Manual, with values converted from July 2002 to July
2020 dollars using an update factor of 1.57.
12
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Table 6: Value of time calculations
Value of time
Off-
AM-peak
Inter-
PM-peak
(July 2021
peak
peak
$/hour)
MBCM 2021,
Percentage of trips by time period
Table 14
Commuting
$12.40
3%
27%
5%
26%
Other purpose
$10.97
95%
65%
80%
66%
Work purpose
$37.92
2%
8%
15%
8%
Composite value
$11.55
$13.51
$15.09
$13.50
of time ($/hour)
Safety impact assessment
A crash analysis has been completed using the Monetised Benefits and Cost
Manual, method A: crash by crash analysis. Waka Kotahi’s Crash Analysis System
(CAS) was used to identify crashes occurring on Wellington City’s urban road
network occurring over a 5-year period between 01 January 2015 and 31 December
2019. A 5-year period has been used rather than a 10-year period in order to
estimate a baseline crash level that takes into account the many safety
improvements that occurred from 2010 to 2014, including 30 km/h zones introduced
in town centres across the city.
Table 7 below outlines the crash modification factors that were used to estimate
crash reduction benefits and the rationale and source for each crash modification
factor. For all crash modification factors, they apply to injury crashes only and do not
apply to non-injury crashes.
To calculate the number of injuries reduced by the options, the crash modification
factor is applied to the streets that receive speed limit reductions, as outlined in
Table 2. For options that include a permanent speed limit reduction, the modification
factor is applied to all injuries in crashes on treated streets. For options that include
variable speed limits, the modification factor is applied to injuries in crashes on
treated streets that occurred between 8:30am and 9:00am and 3:00pm and 3:30pm
on non-holiday weekdays, as these are the times that variable speed zones are
expected to be in operation around schools. This represents a slight over-estimate of
injuries reduced by variable speed limits around schools, as it includes benefits
during school holidays falling outside public holiday periods.
13
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Table 7: Crash modification factors (CMF) used for crash estimation
Intervention
Scenario
CMF
Rationale/Source
Differences in differences analysis of implementation of
50 km/h to
Central
lower speed limit from 50 km/h to 30 km/h in town centres
0.81
in Wellington City. CMF assumed to be half value of 50
40 km/h
scenario
km/h to 30 km/h change. Methodology outlined in
LGWM
Safer Speeds Case for Change (2019)
50 km/h to
Central
Differences in differences analysis of implementation of 30
0.62
km/h zones implemented in Wellington City. Methodology
30 km/h
scenario
outlined in
LGWM Safer Speeds Case for Change (2019)
CMF used by U.S. Department of Transportation Federal
50 km/h to
Higher
Highway Administration.
Islam and Basyouny. "Full
0.50
Bayesian evaluation of the safety effects of reducing the
40 km/h
benefits
posted speed limit in urban residential areas". Accident
Analysis and Prevention, (2015)
50 km/h to
Higher
0.50
Reference is not available. Same CMF as for 50 km/h to 40
30 km/h
benefits
km/h is used, but actual CMF is likely higher.
50 km/h to
Lower
0.90
Half of central estimate scenario
40 km/h
benefits
50 km/h to
Lower
0.81
Half of central estimate scenario
30 km/h
benefits
Table 8 shows the other key parameters that were used for crash benefit estimation.
Given fatal crashes are rare events that have a high cost, fatal and serious injuries
are redistributed in accordance with the fatal to serious ratios outlined in the
Monetised Benefits and Costs Manual (MBCM) 2020. Because there is a large
difference in social cost between fatal and serious injuries, crash reduction benefits
are very sensitive to the assumed fatal to serious injury ratio. A Wellington City
specific fatal to serious injury ratio has been estimated using the total reported fatal
and serious injuries over a 5-year period between 01 January 2015 and 31
December 2019 and the MCBM under-reporting factor for serious crashes. This
methodology yields a ratio that is around one third to one half of the suggested figure
in the MBCM. Using this Wellington City specific ratio in the central benefits
estimation scenario represents a conservative estimate of benefits, relative to the
method set out in the national guidance. The minor crash under-reporting factor used
is for non-pedestrian crashes, while the MBCM suggests a higher factor for minor
crashes involving a pedestrian. As 16% of reported minor injuries in Wellington
involve pedestrians and 14% involve cyclists, the under-reporting factor used likely
represents a moderate under-estimate of minor injury crashes.
14
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Table 8: Key parameters used for crash estimation
Parameter
Value
Source/Rationale
Fatal to serious injury ratio - central
0.03
Wellington City specific ratio
Fatal to serious injury ratio - high
0.07
MBCM (2020), Table A15
Serious crash under-reporting factor
1.50
MBCM (2020) Table A18
Minor crash under-reporting factor
2.75
MBCM (2020) Table A18
Table 9 shows the social costs per injury that were used to monetise crash reduction
benefits. Social costs of injuries are published by the Ministry of Transport, and the
figures used are for injuries on urban roads (Ministry of Transport 2019). Social costs
have been calculated per individual injury using the social cost for each injury in a
crash. This represents a more accurate estimation of crash reduction benefits as
compared to using composite benefit values per crash, as it uses actual rather than
assumed numbers of individuals injured per crash.
Table 9: Social cost of injuries2
Injury severity
Social cost per injury
Fatal
$4,562,000
Serious
$854,000
Minor
$88,000
Total predicted crash reductions are a product of two inputs:
• the effectiveness of the intervention at reducing injury crashes (the crash
modification factor), and
• the number of crashes in the area that receives the intervention.
Figure 5 shows the number of annual injuries, after accounting for under-reporting,
and fatal to serious injuries ratios that are predicted to occur on streets receiving
different speed limit treatments.
• Option 3 (40 km/h default) would be applied over the area with the largest
number of injury crashes, impacting streets that are the location of 71% of
crashes in Wellington City.
• Option 4 (30 km/h default) would have a moderately lower coverage of crash
locations, impacting streets that are the location of 58% of crashes in the city.
The major difference in the crash reductions of Option 3 and Option 4 is the
proportion of network covered by the speed limit change: Option 4 (30 km/h speed
limit) excludes most arterial roads (i.e., most arterial roads remain at 50 km/h),
2 https://www.transport.govt.nz/statistics-and-insights/safety-annual-statistics/sheet/social-cost-of-
road-crashes
15
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resulting in lower coverage of the city than Option 3 (40 km/h) which reduces the
traffic speed limit on most arterial roads to 40 km/h.
Options 2a (permanent at schools) and 2b (permanent at schools (accelerated))
impact streets that are the location of 15% of crashes in the city. While Options 1a
(variable at schools) and 1b (variable at schools (accelerated)) have the same
geographic coverage as 2a and 2b, lower speed limits would only be in force for a
limited time of the day, and only 1.1% of crashes in Wellington City occurred in
school zones while the lower speeds would be in effect (i.e., during the school drop-
off and pick up times).
Figure 5: Predicted annual injury crashes by area
Streets not covered by speed changes
Streets covered by 30 and 40 km/h area wide schemes (excl. schools)
Streets covered 40 km/h area wide scheme only (excl. schools)
School zones - outside school times
School zones - during school times
454
158
170
165
296
12
Note: Option 3 (40 km/h) reduces the traffic speed limit on most arterial roads to 40 km/h whereas
Option 4 (30 km/h speed limit) excludes most arterial roads (which remain at 50 km/h). Since most of
crashes happen on arterial roads, Option 3 (40 km/h) which includes speed reduction on most arterial
roads covers a greater proportion of Wellington City streets compared to Option 4 (30 km/h) which
excludes most arterial roads.
Error! Reference source not found. and
Table 10 present the predicted annual
injury crashes avoided per year by option.
Error! Reference source not found. and
Table 11 present the social costs associated with these crash reductions.
16
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Error! Reference source not found.: Social cost of injuries avoided per year, by option
Fatal
Serious
Minor
$30
s
n
o
Milli $25
sgni
$20
sav
ashr cal $15
u
n
f an
o $10
e
u
Val
$5
$-
1a
1b
2a
2b
3
4
5a
5b
6
Table 11Table 10: Predicted injuries avoided per year, by option
Total
Option
Fatal
Serious
Minor
DSI
injuries
1a: Variable at schools
0.0
0.3
4.2
0.3
4.5
1b: Variable at schools
0.0
0.3
4.2
0.3
4.5
(accelerated)
2a: Permanent at schools
0.1
6.2
58.3
6.2
64.5
2b: Permanent at schools
0.1
6.2
58.3
6.2
64.5
(accelerated)
3: 40 km/h default
0.1
10.5
107.0
10.7
117.7
4: 30 km/h default
0.1
11.1
116.0
11.2
127.2
5a: 40 km/h default +
0.1
10.7
109.1
10.8
119.9
variable at schools
5b: 40 km/h default +
0.1
10.7
109.1
10.8
119.9
variable at schools
(accelerated)
6: 40/30 km/h mix
0.2
16.1
165.0
16.3
181.3
17
Error! Reference source not found.
: Social cost of injuries avoided per year, by option
Fatal
Serious
Minor
$30
s
n
o
Milli $25
sgni
$20
sav
ashr cal $15
u
n
f an
o $10
e
u
Val
$5
$-
1a
1b
2a
2b
3
4
5a
5b
6
Table 11: Social cost of injuries avoided per year, by option
Total
Option
Fatal
Serious
Minor
DSI
injuries
1a: Variable at
$18,607
$286,843
$367,840
$305,450
$673,290
schools
1b: Variable at
schools
$18,607
$286,843
$367,840
$305,450
$673,290
(accelerated)
2a: Permanent at
$341,130
$5,258,791
$5,131,368
$5,599,921
$10,731,289
schools
2b: Permanent at
schools
$341,130
$5,258,791
$5,131,368
$5,599,921
$10,731,289
(accelerated)
3: 40 km/h default
$583,022
$8,987,753
$9,416,704
$9,570,775
$18,987,479
4: 30 km/h default
$614,034
$9,465,825
$10,207,560
$10,079,858
$20,287,418
5a: 40 km/h default
$592,326
$9,131,174
$9,600,624
$9,723,500
$19,324,124
+ variable at schools
5b: 40 km/h default
+ variable at schools
$592,326
$9,131,174
$9,600,624
$9,723,500
$19,324,124
(accelerated)
6: 40/30 km/h mix
$890,039
$13,720,665
$14,520,484
$14,610,704 $29,131,188
18
link to page 19
Table 12 presents the estimated whole of life crash reduction benefits for each of the
options.
Table 12: Whole of life crash reduction benefits of options
Deaths and serious
Discounted crash reduction
Option
injuries avoided – over
benefits – over 40 years
40 years
1a: Variable at schools
$10,202,158
12
1b: Variable at schools
13
(accelerated)
$12,224,154
2a: Permanent at
222
schools
$172,486,300
2b: Permanent at
237
schools (accelerated)
$ 194,835,639
3: 40 km/h default
$344,733,742
405
4: 30 km/h default
$368,335,248
426
5a: 40 km/h default +
368
variable at schools
$284,331,137
5b: 40 km/h default +
variable at schools
401
(accelerated)
$333,346,959
6: 40/30 km/h mix
$528,901,366
602
Key findings from the crash cost estimation are as follows:
• Option 6 (40/30 km/h mix) delivers the highest lifetime safety benefits at $529
million discounted over 40 years.
o This result is because this option treats a greater proportion of
Wellington City streets, as in Option 3 (40 km/h default), but has
greater benefits than Option 3 due to 30 km/h speed limits on non-
arterial streets.
• The next highest performing Option is 4 (30 km/h default) with lifetime benefits
of $426 million.
o While Option 5a (40 km/h default + variable at schools) and 5b (40
km/h default + variable at schools (accelerated)) have higher annual
benefits once fully implemented, they are fully implemented later than
Option 4 (30 km/h default), resulting in lower lifetime safety benefits.
• Options 1a (variable at schools) and 1b (variable at schools (accelerated))
provide the lowest lifetime safety benefits at $10.2 million and $12.2 million
respectively, which are orders of magnitude lower than the other options.
19
o This result is because Options 1a and 1b are applied over a limited
proportion of the road network during a limited time of the day, whereas
in other options lower speeds are permanent and much more widely
applied.
Cost estimation
There are four main types of costs associated with implementing safer speeds:
• signage,
• traffic calming devices,
• implementation costs, and
• annual maintenance costs.
Speed limit signs are regulatory traffic control devices that must be installed where a
speed limit changes. While speed limit signs must always be provided when a speed
limit changes. There are several types of speed limit signs set out in the Traffic
Control Devices 2004 Rule (2021) that may be used depending on the context.
It has been assumed that a range of sign types will be used depending on the speed
zone type and location type. The type of speed limit sign used is dependent on the
degree of behaviour change required, with larger threshold signs used in areas
where there is a significant transition from a high-speed area to a low-speed area.
The types and assumed costs for signs that have been used for cost estimation is as
follows:
• R1-1 Standard
o Used in areas where operating speeds are already in alignment with
the reduced speed limit
o Cost per unit: $500
• R1-5.5 Safer Speed Area Threshold (750 x 1200 mm, approach speed < 60
km/h)
o Used at speed transition points where operating speeds are 40-60
km/h
o Cost per unit: $1,500
• R1-5.5 Safer Speed Area Threshold (900 x 1500 mm, approach speed 60 –
80 km/h)
o Used at speed transition points where operating speeds are 60-80
km/h
o Cost per unit: $2,250
• R1-5.1 Urban/urban Threshold (900 x 1200 mm)
o Cost per unit: $1,800
• R1-6 School zone variable
o Used on main road outside schools and on major roads that intersect
with school zones
o Cost per unit: $11,000
• R1-6.1 School zone fixed
20
o Used on no exit or minor stop or give-way controlled side roads
adjoining school zones
o Cost per unit: $1,000
• R1-7 School zone ends
o Used at the end of school zones
o Cost per unit: $500
When used in isolation, speed limit signs have a limited effect on reducing vehicle
speeds. It has been assumed that speed limit changes will be supplemented by
traffic calming devices in areas where:
• operating speeds significantly exceed the reduced speed limit, or
• threshold points where there is a significant transition from a high-speed area
to a low-speed area.
The types and assumed costs for traffic calming devices that have been used for
cost estimation is as follows:
• Small threshold treatment
o This treatment would be used in areas with approach speeds of less
than 60 km/h, in conjunction with a R1-5.5 (750 x 1200 mm) sign
o This cost includes red threshold paint, visual narrowing with white
paint, and an urban design/welcome element
o Cost per unit: $3,000 (excluding signage)
• Large threshold treatment
o This treatment would be used in areas with approach speeds of 60-80
km/h, in conjunction with R1-5.5 (900 x 1500 mm) or R1-5.1 signs
o This cost includes road narrowing via a kerb extension with a rain
garden and plantings, red threshold paint, and a placemaking/welcome
element
o Cost per unit: $15,000 (excluding signage)
• Threshold treatment with traffic calming
o This treatment would be used in areas with approach speeds of 60-80
km/h, in conjunction with R1-5.5 (900 x 1500 mm) or R1-5.1 signs
o This cost includes a raised platform, painting and remarking, and a
placemaking/welcome element
o Cost per unit: $60,000 (excluding signage)
• School zone raised pedestrian crossing/threshold treatment
o It has been assumed that each school will receive either one raised
pedestrian crossing or one threshold treatment with vertical deflection.
o This cost includes the raised crossing or speed hump, paint, and
enabling drainage works
o Cost per unit: $60,000
• Localised traffic calming
o This treatment would be used on streets where current free flow
speeds are more than 10% above the reduced speed limit.
21
link to page 22 link to page 23
o This cost includes remarking all lane lines and a traffic calming device
every 100 meters.
o Traffic calming devices are assumed to alternate between two
treatments: chicanes with rain garden and plantings and pedestrian
crossings with kerb buildouts and centre traffic islands. This costing
assumes that 50% of devices require enabling draining works.
o Cost per 100 metres: $35,000
To estimate the type and number of speed signs and threshold treatments required,
it was necessary to determine the number of sites where the speed limit would
change under each option. This was undertaken by intersecting road segments
using ArcGIS Pro, with an example shown in
Figure 6 below.
Two types of sites were identified:
• sites where there is an existing speed limit sign that will need replacing, for
example at State Highway exit points, and
• sites where a new speed sign would be required.
Figure 6: Identification of speed sign and threshold treatment sites
Once the number and location of signs required was estimated, it was necessary to
determine the type of sign and threshold treatments that would be required at each
site. This was done by analysing the speed limit change at the boundary and the
mean operating speed at the boundary. Estimated mean operating speeds were
exported from Mega Maps
. Figure 7 shows the mean operating speeds by ONRC
category, as exported from Mega Maps.
22
link to page 23 link to page 24
Table 13 shows the assumed number and type of signs required by option.
Table 14
shows the assumed number and type of traffic calming required by option.
Figure 7: Mean operating speeds within Wellington City by ONRC category
300
250
20-24.9 km/h
kro
25-29.9 km/h
tw 200
e
n
30-34.9 km/h
ad
o 150
f r
35-39.9 km/h
o
s
e
40-44.9 km/h
tr
e 100
m
45-49.9 km/h
oliK
50-54.9 km/h
50
55-59.9 km/h
-
Access
Secondary Collector Primary Collector
Arterial
Source: Megamaps
Table 13: Estimated number and type of signs required by option
Option
1a & 1b
2a & 2b
3
4
5a & 5b
6
R1-1
Fixed
0
0
170
12
170
12
R1-5.5
Safer Speed Area
0
0
138
734
138
734
Threshold (small)
R1-5.5
Safer Speed Area
0
0
14
8
14
8
Threshold (large)
R1-5.1
0
0
24
4
24
4
Urban/urban threshold
R1-6
217
0
0
0
217
0
School zone variable
R1-6.1
72
289
0
0
72
0
School zone fixed
R1-7
School zone ends
289
289
0
0
289
0
Total signs
578
578
346
758
924
758
23
Table 14: Estimated number and type of traffic calming required by option
Option
1a & 1b
2a & 2b
3
4
5a & 5b
6
Small threshold
treatment
0
0
16
2
16
2
Large threshold
0
0
30
15
30
15
treatment
Threshold treatment
0
0
2
7
2
7
with traffic calming
School zone raised
pedestrian
81
81
81
81
81
81
crossing/threshold
treatment
Localised traffic
0
0
10
37
10
37
calming (km)
24
Figure 8: Small threshold treatment Figure 9: Large threshold treatment
Figure 10: Threshold treatment with traffic calming Figure 11: School zone raised pedestrian crossing/threshold treatment
25
Figure 12: Raised pedestrian crossing buildouts and centre island Figure 13: chicanes with rain garden and plantings
26
link to page 27
The implementation costs that have been accounted for in cost estimates are as
follows:
• Communication, consultation, and engagement
o This cost covers the preparation and dissemination of consultation and
engagement materials as well as communication of speed limit
changes to the community
o Cost: $100,000 for area-wide speed limit changes and $40,000 per
round of school zone speed limit changes
• Project management
o This cost covers the preparation of the detailed business case and
detailed design of interventions
o Cost: 15% of physical infrastructure and communication, consultation,
and engagement costs
• Contingency
o This costs for unanticipated cost escalations that may arise during
detailed design phase
o Cost: 20% of total option cost, including communication, consultation,
engagement, and project management.
Additional annual maintenance arising from end-of-life sign replacement and upkeep
of installed threshold treatments has been assumed as:
• Sign replacement at 10-year intervals after installation (i.e. signs installed in
Year 1 replaced in Year 11, Year 21, Year 31 etc)
• Threshold maintenance at 2% of installation cost annually for all installed
treatments.
Table 15 below sets out the estimated undiscounted costs associated for each
option across three expenditure categories: signage, traffic calming, implementation,
and maintenance costs. As the options have different implementation timelines
across a ten-year period, the undiscounted costs set out in this table differ from the
discounted costs used in the final cost benefit calculation.
Table 15: Cost estimation summary by option (undiscounted)
Option
Signage
Traffic
Implement
Maintenance
Total
calming
costs
costs
1a: Variable
$2,603,500
$4,860,000
$3,386,336
$11,154,180
$22,004,016
at schools
1b: Variable
at schools
$2,603,500
$4,860,000
$3,386,336
$11,540,100
$22,353,936
(accelerated)
2a:
Permanent at
$433,500
$4,860,000
$2,420,562
$4,966,680
$12,680,742
schools
2b:
Permanent at
$433,500
$4,860,000
$2,420,562
$5,316,600
$13,030,662
schools
(accelerated)
27
link to page 28 link to page 29 link to page 30
3: 40 km/h
$366,700
$8,978,000
$3,689,676
$7,924,880
$20,959,256
default
4: 30 km/h
$1,132,200
$18,461,000
$7,735,354
$17,426,960
$44,755,514
default
5a: 40 km/h
default +
$2,970,200
$8,978,000
$5,118,122
$15,287,800
$32,354,122
variable at
schools
5b: 40 km/h
default +
variable at
$2,970,200
$8,978,000
$5,118,122
$15,651,520
$32,717,842
schools
(accelerated)
6: 40/30 km/h $1,132,200 $18,461,000
$7,735,354
$17,426,960
$44,755,514
mix
Cost benefit analysis
Table 16 shows key parameters used in the economic analysis that have not been
outlined in previous sections.
Table 16: Key parameters used for economic analysis
Parameter
Value
Source/Rationale
Discount rate
4%
MCBM (2020)
Analysis period (years)
40
MCBM (2020)
Vehicle occupancy rate (people/vehicle)
1.2
WCC Cordon Surveys
Bus occupancy rate (people/bus)
15
GWRC data
Annualisation factor
245
Working days per year
Table 17 and
Figure 14 show the estimated discounted benefits and disbenefits for
each of the 9 options.
28
Table 17: Cost benefit analysis summary
Annual
Crash
Construction
Travel time
DSI
Option
reduction
BCR
costs
disbenefits
Crashes
benefits
avoided
1a: Variable
$9,051,375
$10,202,158
$4,118,085
0.3
0.7
at schools
1b: Variable
at schools
$10,412,025
$12,224,154
$4,934,261
0.3
0.7
(accelerated)
2a:
Permanent
$6,451,373
$172,486,300
$21,285,503
6.2
23.4
at schools
2b:
Permanent
$7,412,800
$194,835,639
$25,504,140
6.2
22.8
at schools
(accelerated)
3: 40 km/h
$12,518,521
$344,733,742
$286,942,004
10.7
4.6
default
4: 30 km/h
$26,231,737
$368,335,248
$366,294,023
11.2
0.1
default
5a: 40 km/h
default +
$14,652,748
$284,3331,137
$236,723,819
10.8
3.2
variable at
schools
5b: 40 km/h
default +
variable at
$16,137,783
$333,346,959
$277,310,942
10.8
3.5
schools
(accelerated)
6: 40/30
$26,240,932
$528,901,366
$326,618,013
16.3
7.7
km/h mix
29
Figure 14: Costs and benefits by option
Key findings from the cost benefit analysis are as follows:
• Benefits outweigh costs for six of the nine options considered, suggesting
there is a strong case for safer speeds in Wellington City
• Two of the nine options provide very high value for money, with cost benefit
ratios over well over 10
• Construction costs are a relatively small contributor to cost benefit ratios, and
are strongly outweighed by the two other inputs: crash reduction benefits and
travel time disbenefits
• Option 2a (Permanent at schools) and Option 2b (Permanent at schools
(accelerated)) provide the highest benefit cost ratios, followed by Option 6
(40/30 km/h mix).
The results presented here represent a conservative estimate of the benefits
associated with the traffic speed reduction. As stated earlier in the report, reducing
traffic speeds in urban areas is typically planned to help encourage more walking
and cycling for transport, so it is reasonable to assume that the changes would result
in an increase in number of walking and cycling trips and a reduction in vehicle travel
for shorter trips. However, due to a difficulty to estimate the magnitude of this mode
shift and resulting health benefits from increasing physical activity associated with
active transport, the benefits of mode shift and corresponding physical and mental
health benefits were not included in this analysis. In addition, mode shift would
produce travel time benefits which would offset travel time disbenefits from lower
average traffic speeds. Therefore, the economic assessment represents a
conservative estimate of the benefits of speed limit changes.
30
link to page 31 link to page 32
Sensitivity testing
Due to the inherent uncertainty involved in predicting future outcomes, it is important
to test the sensitivity of the results to the assumptions that have been used to
undertake the analysis. Sensitivity testing was undertaken to gain an understanding
of how sensitive the results are to the following inputs:
• crash modification factor
• fatal to serious injury ratio
• construction costs
• travel time disbenefits
Table 18 outlines the scenarios that have been used for sensitivity testing.
Table 18: Sensitivity testing scenarios
Discount
Costs and disbenefits
Scenario
Benefits
rate
A
Central CMF, Central
Central costs,
4%
fatal to serious injury
Central case
central disbenefits
ratio
B
Central CMF, Central
Central costs,
Higher discount
6%
fatal to serious injury
central disbenefits
rate
ratio
C
Low CMF, Central fatal
Central costs,
4%
Lower benefits
to serious injury ratio
central disbenefits
D
Central CMF, Central
50% higher costs,
Higher costs
4%
fatal to serious injury
50% higher disbenefits
and disbenefits
ratio
E
Low CMF, Central fatal
50% higher costs,
Extreme
6%
to serious injury ratio
50% higher disbenefits
bounds - low
F
High CMF, High fatal to
Central costs,
Extreme
4%
serious injury ratio
central disbenefits
bounds -high
CMF = Crash modification factor.
The results of sensitivity testing are outlined in
Table 19, showing the cost benefit
ratio for each option under each sensitivity test scenario.
31
Table 19: Sensitivity testing results, BCR for each option
A
B
C
D
E
F
Option
Central
Higher
Lower
Higher
Extreme
Extreme
case
discount
benefits
costs and
bounds -
bounds -
rate
disbenefits
low
high
1a
0.7
0.5
0.1
0.3
-0.1
1.1
1b
0.7
0.5
0.1
0.3
-0.1
1.2
2a
23.4
18.1
10.1
14.5
5.6
34.3
2b
22.8
17.1
9.7
14.1
5.3
33.5
3
4.6
3.5
-15.7
-13.3
-13.7
54.4
4
0.1
0.1
-6.9
-4.6
-9.3
5.7
5a
3.2
2.4
-6.5
-3.2
-9.7
37.2
5b
3.5
2.6
-6.9
-3.4
-10.3
39.7
6
7.7
5.8
-2.4
-5.2
-12.0
24.4
Efficiency
Very low
Low Medium
High Very High
(<1.0)
(1.0-2.9)
(3.0-5.9)
(6.0-9.9)
(>=10.0)
rating
Key findings from the sensitivity testing are as follows:
• When a higher discount rate is considered, results are stable relative to the
central case results. This demonstrates that all options are approximately
equally sensitive to the discount rate applied.
• All options are sensitive to lower benefit rates, as well as higher costs and
disbenefits. Option 2a (permanent at schools) and Option 2b (permanent at
schools (accelerated)) are the least sensitive to these parameters, retaining a
BCR of greater than one in all sensitivity tests.
• Accelerated programmes, Option 2b (permanent at schools (accelerated))
and Option 5b (40 km/h default + variable at schools (accelerated)) generally
outperform the standard timeframes in the central case and underperform in
the sensitivity tests. This indicates a case for accelerated timeframes to be
considered, coupled with an increased risk of underperformance if either
crash reductions are over-predicted, or travel time increases are under-
predicted, or both.
32
link to page 33 link to page 34
Incremental cost benefit analysis
As discussed above, several options return positive cost benefit ratios, indicating
there are several options which may prove to be feasible.
To analyse the additional benefit unlocked by higher investment levels an
incremental cost benefit ratio has been calculated for each option. The overall
process is summarised in the following steps:
• Options sorted in ascending order of net cost.
• Options sorted in ascending order of net benefit.
• Incremental cost and benefit calculated by subtracting the value of the
previous option from the current candidate option, then Incremental BCR
calculated.
• Incremental BCR of greater than 1.0 indicates the additional spending
generates a return greater than the additional outlay. If this is the case the
option is selected as the new candidate option, otherwise the option is
rejected.
• Process is repeated for each additional option.
As the option with the lowest total cost, Option 2a (permanent at schools) is selected
as the first candidate option. Incrementally, Option 2b (permanent at schools
(accelerated)) has a BCR of 12.2, indicating that the accelerated timeline returns
significant additional benefit over the standard timeframe.
Options 1a, 1b, 3, 5a, and 5b all return incremental BCRs of less than 1.0, the
additional costs for each option are not matched by increases in the net benefits
compared to Option 2b (permanent at schools (accelerated)). This is mainly due to
the increased travel time disbenefits in the network-wide speed limit change options.
Option 6 (40/30 km/h mix) returns an incremental BCR of 1.2, demonstrating
additional benefit in excess of cost compared to Option 2b (permanent at schools
(accelerated)), and is the final candidate solution selected.
The incremental costs, benefits and BCR are shown in
Table 20 for each option.
Figure 15 displays the net costs and benefits for each option, with the candidate
options highlighted along the selection boundary.
Table 20: Summary of incremental BCR calculations
Option
Net Cost
Net Benefit Incremental
Incremental
Incremental
Cost
Benefit
BCR
2a:
Permanent at
$9,237,883
$151,200,797
$9,237,883
$151,200,797
16.4
schools
2b:
Permanent at
$10,719,330
$169,331,499
$1,481,447
$18,130,702
12.2
schools
(accelerated)
1a: Variable
$14,464,732
$6,084,073
$3,745,402
-$163,247,426
-43.6
at schools
33
1b: Variable
at schools
$16,765,379
$7,289,894
$6,046,049
-$162,041,605
-26.8
(accelerated)
3: 40 km/h
$17,594,847
$57,791,738
$6,875,517
-$111,539,761
-16.2
default
5a: 40 km/h
default +
$22,806,395
$47,850,556
$12,087,065
-$121,480,943
-10.1
variable at
schools
5b: 40 km/h
default +
variable at
$24,960,289
$56,036,017
$14,240,959
-$113,295,482
-8.0
schools
(accelerated)
4: 30 km/h
$37,203,845
$2,041,225
$26,484,515
-$167,290,274
-6.3
default
6: 40/30 km/h
$37,203,845
$202,283,353
$26,484,515
$32,951,854
1.2
mix
Figure 15: Net cost and benefit by option with candidate options and resulting selection boundary
34
Conclusions
This cost benefit analysis has demonstrated that there are several approaches to
delivering safer speeds in Wellington that substantially reduce the social cost of road
crashes and deliver value for money.
When comparing across the 9 options:
• Option 6 (40/30 km/h mix; total cost $44.8 million) provides the highest crash
reduction benefits and high value for money in the central case. However, it
has a negative BCR in three sensitivity tests, due to high costs and relatively
high travel time disbenefits.
• Option 4 (30 km/h default; total cost: $44.8 million) provides the second
highest crash reduction benefits. However, it has a BCR under 1 in four out of
five sensitivity tests, reflecting high costs and high travel time disbenefits.
• Options 2a (permanent at schools; total cost: $12.7 million) and 2b
(permanent at schools (accelerated); total cost: $13.0 million) are the options
with the highest value for money but have lower total benefits compared to
options 3, 4, 5a, 5b, and 6. The high BCR reflects lower costs and disbenefits
compared to the other options with higher benefits. Options 2a and 2b also
perform well across all sensitivity tests and are the only options with a positive
BCR in the extreme low bound sensitivity test.
• Option 3 (40 km/h default; total cost: $21.0 million) provides medium value for
money under the central scenario and has a positive BCR in two out of five
sensitivity tests.
• Options 5a (40 km/h default + variable at schools; $32.4 million) and 5b (40
km/h default + variable at schools (accelerated); $32.7 million) provide high
benefits and have a medium value for money in the central case. These two
options deliver a negative BCR in in three out of five sensitivity tests.
• Options 1a (variable at schools; total cost: $22.0 million) and 1b (variable at
schools (accelerated); total cost: $22.4 million) are the worst performing
options, with a BCR of under 1 in the central case and in four out of five
sensitivity tests.
Incremental cost benefit calculations indicate that, depending on the total budget
available, the most efficient options are Option 2a (permanent at schools), Option 2b
(permanent at schools (accelerated)), and Option 6 (40/30 km/h mix).
This cost benefit analysis likely represents an under-estimate of the benefits of lower
speed limits. This is because it has not assumed any change in travel behaviour due
to traffic speed limit reduction. Urban speed limit changes are typically designed to
help encourage more walking and cycling, so it is reasonable to assume that the
speed limit reduction, particularly the network-wide reductions, would result in an
increase in walking and cycling trips and a reduction in private vehicle travel for
shorter trips. An increase in walking and cycling would result in health and
environmental benefits and a reduction in travel time disbenefits from reduced traffic
speed. As these benefits have not been taken into account in the analyses
presented in this report, the actual benefits and corresponding cost benefit ratios for
35
all options (and particularly network-wide options) are likely to be higher than has
been estimated in this analysis.
36
Appendix
Streets Excluded from 30 km/h Default, 40 km/h Default, and 40/30 km/h Mix
Streets excluded from the
30 km/h Default urban speed limit:
• SH1
• Broadway
• Moorefield Rd
• SH2
• Broderick Rd
• Moxham Ave
• Motorway On/Off
• Brooklyn Rd
• Newlands Rd
ramps
• Burma Rd
• Ngaio Gorge Rd
• Centennial
• Churchill Dr
• Ohiro Rd
Highway
• Cockayne Rd
• Onepu Rd
• Lambton Area
• Constable St
• Onslow Rd
Unit
• Curtis St
• Park Rd
• Willis Street-
• Dundas St
• Queens Dr
Cambridge
• Evans Bay Pde
• Raroa Cres
Terrace Area Unit
• Ferry St
• Raroa Rd
• Makara-Ohariu
• Glasgow St
• Rintoul St
Area Unit
• Hutt Rd
• Rongotai Rd
• Takapu
• Johnsonville Rd
• Salamanca Rd
• Adelaide Rd - Mt
• Kaiwharawhara
• Takapu Rd
Cook
Rd
•
•
Taranki St
Aotea Quay
• Karori Rd
•
•
The Esplanade
Waterloo Quay
• Kelburn Pde
•
•
The Parade
Customhouse
• Upland Rd
• Thorndon Quay
Quay
•
•
•
Glenmore St
Tinakori Rd
Jervois Quay
•
•
•
Khandallah Rd
Wadestown Rd
Cambridge
• Kilbirnie Cres
• Wallace St
Terrace
•
•
Lyall Pde
• Webb St
Kent Terrace
•
•
Main Rd
• Wilton Rd
Taranaki St
•
•
Middleton Rd
Adelaide Rd
•
•
Miramar Ave
Aro St
Streets excluded from the
40 km/h Default and
40/30 km/h Mix urban speed limit:
• SH1
• Aotea Quay
• SH2
• Waterloo Quay
• Motorway On/Off ramps
• Customhouse Quay
• Lambton Area Unit
• Jervois Quay
• Willis Street-Cambridge Terrace
• Cambridge Terrace
Area Unit
• Kent Terrace
• Makara-Ohariu Area Unit
• Taranaki St
• Takapu
• Hutt Rd
• Adelaide Rd - Mt Cook
• Centennial Highway
37
Assumed extent of permanent and variable speed limits at schools
38
Assumed extent of default 30 km/h (excluding most arterials) urban speed limit
39
Assumed extent of default 40 km/h (including most arterials) urban speed limit
40
Assumed extent of default 40 km/h urban speed limit and 30 km/h speed limits at schools
41
Assumed extent of default 40 km/h and 30 km/h mixed speed default urban limit
42
