Category Archives: Public Transport

Safer urban car lane widths

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Readers need to be aware that this post does have a bias toward giving weaker road users a higher priority for road space. My reading of these design manuals is therefore to identify the widths providing greatest benefit for people aged 8 to 80.
First warning: For this post, lane width is about the distance between painted lines or changes in road surface texture. Kerbs/road bumps greater then 50mm in height limit the available options. See the photo at the end of this post.

New Zealand legislation states that a “lane for the use of vehicular traffic … is at least 2.5 m wide” Reprinted 1 October 2017 – Land Transport (Road User) Rule 2004 (SR 2004/427)

Here is an example (in Schiedam) of narrowed motor vehicle lanes with the cycle lane width being maintained through the intersection. As we can all see, this doesn’t mean excluding heavy traffic (note bus stop). What it does mean is that the safety* a cycle lane width gives can be continued through the intersection.

*“Cycle lanes … provide a modest 10% safety improvement for cyclists, but 30% for pedestrians” This is from the NZTA Pedestrian planning and design guide Table 6.3

Data collected from the Minneapolis-St. Paul and Oakland County – Detroit areas does not support the idea of wider lanes being safer for motorists.

“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 midblock segments (& arterial intersection approaches) leads to increases in accident frequency.” P23 (P25)

Ref: Relationship of Lane Width to Safety for Urban and Suburban Arterials – 2007 by Ingrid B. Potts, Douglas W. Harwood, and Karen R. Richard

Measures from Tokyo & Toronto also do not support wider lanes being more efficient for motorists. Ref: Narrower Lanes, Safer Streets – Dewan Masud Karim – 2015

Impact on Traffic Capacity and Congestion:

“Contrary to common belief, the results clearly demonstrate that narrower travel lanes, particularly 3.0m lanes, carry the highest traffic volumes (18% higher compared to 3.5m lane) … there is no measurable decrease in urban street capacity when through lane widths are narrowed from 3.7m to 3.0m … Traffic delays on urban roads are principally determined by junctions, not by midblock free flow speeds” p12

Large Vehicles and Narrower Lanes:

“Low volume trucks (less than 5%) experience no operational problems for narrower lane widths … For buses, it suggests using 3.3m for mixed traffic conditions and 3.0m where buffered bicycles lanes exist” p13

Lane widths to avoid – From Handbook for cycle-friendly design by UK based Sustrans 

“Avoid widths between 3.1 and 3.9m” p17

“Bus lanes widths … 3.2m to 3.9m to be avoided” p19

In my opinion it is particularly important that when narrowing lanes that kerbs and speed bumps are kept as low as possible. People stop for a variety of reasons. Bumps can make the ride in a bus uncomfortable or an ambulance trip worse than it needs to be.

Photo Gottingen – Lange Geismar Str

Past Blog post on lanes

A good one way cycle lane width = 2m+

4 lane roads when to

Lane width and cars per hour per lane

Number of cars per lane

Post card from Hann. Munden Rail station

In 2015 I spent the best part of a week in Hann. Munden. This post benchmarks its rail service compared to what we could have in Hamilton NZ (pop 156,800: density 1,400 p/km2).

To help understand the population base that supports the Hann. Munden rail service, let’s first note there are two rail services between the city of Gottingen (pop 116,891: density 1,000 p/km2) and the city of Kassel (pop 194,747: density 1,800 p/km2). The blue line is a direct service (19 minutes, distance of about 50km), which then continues on to Frankfurt. I interpret this as a fast, two trains per hour service. Link – Gottingen to Kassel time table

The second is the green line, which is a local Gottingen to Kassel (60 minutes) service passing through the rail station at Hann. Munden (pop 23,668: density 200 p/km2). I regard this as an hourly service. Link – Hann. Munden station time table

Hann Munden Rail Map

Now to bench mark this against a Hamilton rail service, listing equally sized population bases as in the table below.

City/Town – Population Population base Distance
Hamilton – 156,800

Morrinsville – 7,490

Tauranga – 124,600

288,890 100 km
Kassel – 194,747

Hann. Munden – 23,668

Gottingen – 116,891

335,406 50 km
Hamilton – 156,800

Ngaruawahia – 5,100

Huntly – 7,670

Pukekohe – 29,000

Manukau – 375,700

574,270 100 km

The challenge Hamilton faces is that it is twice the distance to reach a supporting population, making the travel time between cities over 1 hour.

But is this a real issue? The blue line in the Hann. Munden map is a fast city-to-city service; the green line is about picking up people in smaller towns. The Hamilton to Auckland service should be very much about servicing the towns between our main centres; we must not just focus on travel between the two major cities, but more on supporting the people in the towns between, where most would be happy to choose journeys of about an hour. This would include trips between Te Kauwhata and Hamilton (50km) or Mercer and Ellerslie (50km).

Hann Munden cantus train Hann Munden Train ticket ATM

Image: Cautus train Hann.Munden station & Ticket machine on DB train to Kassel

It’s also important to note that Gottingen and Hann. Munden are in the state of Lower Saxony, while Kassel is in the state of Hesse. These are very different places, with different histories, but are focused on giving access to the maximum number of people travelling between their cities.

The New Zealand approach often feels as though it limits the movement of people that live between city centres. Outside of Auckland we get very good funding to support road traffic, which is OK unless you need to visit Auckland. Then you are wasting time. Once in Auckland, only a local can predict travel times; for an outsider the motorway network can feel like being in a swampy river-mouth lagoon at high tide.