technical note
PROJECT
THE PARADE CROSS SECTION
SUBJECT
INDEPENDENT REVIEW
TO
KARL HANCOCK
FROM
JOE HEWITT
REVIEWED BY
SANDY MILLS
DATE
23 JULY 2014
1 INTRODUCTION
Thank you for sending us through the information for the independent review of the proposed
changes to The Parade cross section. We have reviewed the information provided and make the
following comments with respect to the minimum standard cross section/s as proposed.
2 USE OF MINIMUMS
2.1 Vehicle Lanes
In general I support the application of minimum standards provided the circumstances are right and a
robust review has been undertaken. In this instance, I think the circumstances and location are
appropriate.
The Parade is relatively flat and straight, moderately trafficked and through largely residential suburbs.
Narrow traffic lanes help to reinforce slower vehicle speeds; 3 m is typically the “narrowest”
acceptable in the NZ context (recognising that there are examples of narrower lane widths in places),
and would support appropriate vehicle speeds expected in an environment like The Parade. From
work Flow has previously undertaken, I quote the following with respect to the suitability of minimum
lane widths
AUSTROADS recommends a lane width between 3.0 – 3.3 m for Urban Arterials with low truck volumes.
International research suggests that there is no increase in risk related to lane width. Research by
Potts, Harwood, and Richard, presented at the 2007 TRB Conference comes to the following conclusion:
“Analysis of geometric design, traffic volume, and accident data collected in NCHRP Project 17-
26 has found that, with limited exceptions, there is no consistent, statistically significant
relationship between lane width and safety for approaches to intersections on urban and
suburban arterials. There is no indication that the use of 3.0- or 3.3-m (10- or 11-ft lanes),
rather than 3.6-m (12-ft) lanes, for arterial intersection approaches leads to increases in
accident frequency. There are situations in which use of narrower lanes may provide benefits in
traffic operations, pedestrian safety, and/or reduced interference with surrounding
development, and may provide space for geometric features that enhance safety such as
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medians or turn lanes. The analysis results indicate narrow lanes can generally be used to
obtain these benefits without compromising safety.”
“It is concluded from this research that there is no indication that crash frequencies increase as
lane width decreases for arterial roadway segments or arterial intersection approaches.”1
The Institute of Transportation Engineers (ITE) published a guideline for the design of major urban
thoroughfares. The guideline, called “Context Sensitive Solutions in Designing Major Urban
Thoroughfares for Walkable Communities”2 recommends lanes to be 10 – 11 ft. (3.05 – 3.35 m) wide on
urban arterials with a design speed of 35 mph (56 km/h). .
A study undertaken in 2002 by the Centre for Transport Studies of the London Imperial College of
Science, Technology and Medicine, focused on road safety across all fifty states in the U.S. and uses
data from fourteen years3. This research analyses how different road infrastructure improvements
affect the number of serious injury or fatal crashes. The conclusion of this research is that arterial
roads with lane widths of 9 or 10 ft (2.75 or 3.05 m) show a lower than average number of injuries or
fatalities. Roads with a lane width of 12 ft or more (3.6 m) have a higher rate of injuries or fatalities.
This shows that while wider lanes are commonly considered safer, in reality wider lanes cause more
injuries and fatalities
2.2 Parking
With respect to the parking lane, 2 m is typically recognised as the minimum width in the New Zealand
context, and would seem to be no different than is currently being provided along The Parade. I
understand that safe-hit posts are proposed for installation within the buffer and I suggest that other
separators are considered as possibly more appropriate alternatives, for example an “armadillo” type
hump may be better. The issues I see with the buffer area are:
How can the cycle lane be made useable for cyclists who are looking to overtake another cyclist?
This could become more of an issue should cyclist volumes significantly increase and could be
site specific depending on the range of cyclists on the corridor (novice, children, commuter,
training etc)
How to ensure that vehicles do not park within the buffer area
The ability for the passenger door to be safely opened and whether the use of safe-hit posts
would be an issue for motorists’ (hitting posts with their vehicle door).
It must also be recognised that there will be increased pedestrians crossing the cycle lane travelling to
and from their parked vehicles, and the increased likelihood of pedestrians dwelling within the buffer
zone as they load/unload goods, children etc from their vehicles.
1 Potts, Harwood, and Richard (2007),
Relationship of Lane Width to Safety for Urban and Suburban Arterials
Transportation Research Board 2007 Annual Meeting
2 Institute of Transportation Engineers (2006),
Context Sensitive Solutions in Designing Major Urban Thoroughfares for
Walkable Communities”
3 Noland, R.B., (2002),
Traffic Fatalities and Injuries: The Effect of Changes in Infrastructure and Other Trends, Imperial
College of Science, Technology and Medicine, London
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2.3 Cycling
In terms of the cycle lanes, specifically where the carriageway becomes narrow, the cycle lanes have
been reduced to 1.4 m with a 0.6 m buffer. This is considered very tight, indeed possibly too narrow,
to enable a faster moving cyclist to pass a slower moving cyclist. If there are no posts in the buffer
space and/or a gap in the use of the on-street parking, there may be the ability for the faster moving
cyclist to swing out and around the slower moving cyclist. In addition, well-constructed channels and
flush mounted stormwater grates will help the slower cyclist to shift as far left as practicable.
In terms of the issues around the narrow buffer zone and the conflict with an opening vehicle door it is
noted that not every vehicle has a passenger, but every vehicle does have a driver. So there is a much
lower incidence of passengers exiting the vehicle than via the driver door which must be opened at the
start and end of every journey. So the perceived risk is much lower for a cyclist striking a passenger
door. Again this reinforces the absolute need to ensure the edge of seal and stormwater grates are of
a high quality to enable a cyclist to pass as close to the kerb as is practicable.
2.4 Pedestrians
Mention is made to the fact that removing the flush median will make pedestrians crossing The Parade
more difficult. Consideration may need to be given to more “formalised” locations where pedestrians
can cross, situated at identifiable desire lines. This could see parking removed about these locations
and the kerb extended out to reduce the overall crossing distance, whilst maintaining the cycle lanes.
3 DESIGN DETAILS TO CONSIDER
I recognise that what you have provided are typical mid block cross sections, and that as these are
applied to the actual corridor there will be a need to vary the cross sections to match the land use
activities. However, I thought it worth outlining some of the matters that came to mind as I reviewed
the information:
Given that cyclists would be travelling closer to the kerb, in some situations within a constrained
lane width, it is imperative that there is very little, if any, lip between the edge of seal and the
channel and that all stormwater grates are flush mounted and cycle friendly
Careful consideration of pedestrian crossing and refuges and the ability to accommodate these.
I would expect some on-street parking could be impacted to accommodate this
Enforcement, particularly in the early stages of implementation, to ensure vehicles do not park
in the buffer area
Consideration of alternative separators if poles could impact on vehicle doors
Recommendation of associated advertising campaign to inform and educate the public as to
how to behave and treat the new cross section (including the reasons for the cross section
change and the expected outcomes). Cycle lanes inside parking is a relatively new concept in NZ,
and it would be beneficial to try and lay the “ground rules” for how you want these to operate.
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4 USING MINIMUM STANDARDS ELSEWHERE
I am of the opinion that there are always compromises that need to be made; and the space allowed
for the various modes within each cross section is always site specific. What might be suitable for The
Parade may not be suitable for other areas. Whilst I consider minimum standards should be
considered on a site by site basis rather than a precedent established in a specific location, if some of
the widths adopted for The Parade are to be used elsewhere I consider that there are a number of
actions that would need to happen:
Undertake a similar option assessment as that done for The Parade to weigh up the pros and
cons of each
Consider the removal of parking as a higher priority on arterials
Monitor The Parade to see how well the new cross section works, undertake user surveys
(cyclists, pedestrians, motorists and residents), assess crash records and update traffic speed
data to see if everything is working as expected. It would be useful to report these findings for
industry wide interest.
Reference: S:\wccx\TN1A140723.docx - Karl Hancock
