Tuesday, 9 January 2018

Lane Width: A Guide for Drivers

A NEW LAW


Western Australia has recently changed the law relating to motor vehicles passing a person cycling. Previously the road rules required drivers to give 'sufficient distance' when overtaking. This was considered too vague and subject to poor interpretation by some drivers who put people at risk of serious injury or death by passing too close.

The new law requires drivers to give a minimum of 1 metre distance between their vehicle and a person on a cycle in speed zones of up to 60 km/h. In speed zones over 60 km/h a distance of 1.5 metres is required. Considerate drivers already did this so it's not a big change for them. For the remaining aggressive, reckless and stupid drivers they will risk a fine of $400 and the additional penalty of 4 demerit points.

In Western Australia, if we acquire 12 demerit point on our driving license within a period of three years we lose the privilege of driving.


One of the concerns raised prior to the introduction of these new laws was the potential difficulty drivers may have in determining the correct distances. The simple answer is, if in doubt, allow more space. Most cars are around two metres wide, so one metre is about half the width of a car. In the 70 km/h and faster zones, it is probably best for drivers to changes lanes completely in the same way they would pass a slower motor vehicle.


PHYSICAL RESTRICTIONS


Passing (or overtaking) a slower moving motor vehicle or cycle is only possible when the street design allows it. On streets with a single carriageway in each direction, it is possible to cross the centre line providing there is no oncoming traffic and no raised median or other obstructions. 

Newcastle Street Perth Western Australia

In Western Australia it has become relatively popular for local governments to add raised medians with trees. This is a strategy to calm traffic and add greenery to neighbourhoods. Unfortunately this is often done with no apparent consideration that the street may be used for cycling. The speed limits, which are usually 50 km/h, remain the same. Streets that were previously undivided and acceptable for cycling are changed into cycling black-spots.

Anzac Road Mount Hawthorn "before" (Google Streetview)
Anzac Road Mount Hawthorn "after" (Google Streetview)

Once the street is made too narrow to allow a motor vehicle to pass, it creates a difficult situation. To avoid a collision, the driver must slow their vehicle to cycling speed. This may be a reduction from 50 km/h to just 15 km/h. For the cyclist, the fear of being hit from behind is greater and there is the added stress of being a speed restriction for drivers. 

The most dangerous situations arise when there is a potential gap an impatient driver might be tempted to push through. If the gap is not wide enough it can result in death or serious injury.

At these narrow locations it may be possible for the cyclist to move to a footpath but that usually comes with the alternative risk of being hit by cars reversing out of driveways. Travelling on a footpath also has the inconvenience of having to stop at every street crossing. Where pedestrians are using the paths, they have priority so cycling becomes more difficult.

For the cyclist, these narrow and dangerous sections of streets can come as a surprise when travelling along an otherwise relatively safe environment. With time, cyclists will learn to avoid these places, but drivers need to be aware they will occasionally encounter a person on a cycle.

Spatial awareness is not something everyone possesses in equal measure. The guide below provides helpful details of several locations around Perth where it is legally impossible to pass a person on a bicycle. All the locations measured have central median restrictions, narrow lanes and traffic speeds of at least 50 km/h. Depending on the width of the motor vehicle, some streets will allow passing by drivers in cars, but at all of the locations listed, passing with a large truck or bus is not legally possible.


DESIGN RULES


Austroads has multiple publications which provide guidance for planners and engineers working in Australia and New Zealand. It appears not all planners follow the guides when constructing local streets. For example, the lane width in Newcastle Street Perth shown above, is 3.3 metres. This is  specifically a width not recommended by Austroads. The Guide to Traffic Management Part 8: Local Area Traffic Management (2016 Edition, p126) states

"Care needs to be taken that the introduction of LATM treatments that narrow the road carriageway width do not create safety problems for cyclists. 
Practice should be that lane widths are either designed to be wide enough in all instances to allow the safe passage of a cyclist and a vehicle side by side (3.7 m or more) or narrow enough to permit the passage of a vehicle or bicycle only (3.0 m or less). Widths in between these two extremes create squeeze points and result in conflicts. 
 Local streets with speed environments of 50 km/h or more should be 4.2m or wider in order to be satisfactory for cyclists."

Newcastle Street would be a safer place to cycle if the City of Perth designers followed the current Austroads guide. However, the Austroads guide does not match the current standard for cycling safety for the majority of Australian states that have adopted the new minimum passing distance laws.

Austroads specifies a minimum width of 4.2 metres, however that is not wide enough to safely allow the largest vehicles to pass a person cycling. The width of a cyclist is 1 metre. The legal gap between cyclist and passing vehicle is also 1 metre. Typical buses and large trucks are 2.7 metres wide (including mirrors). Therefore the minimum width of the lane required for a large vehicle with a bicycle is 4.7 metres, not 4.2 metres.

MINIMUM LANE WIDTH 4.7m WITH PLANTED MEDIANS



MORE DETAILS

MEASURING THE LANE

In the guide below, the width described is the distance between kerbs. Or, in situations with parking bays, it is the distance between the kerb on the median and the edge of the parking bay. In some situations the median has flush concrete edging around trees, at those locations the flush concrete is included as a usable part of the carriageway.

CYCLIST ENVELOP

Some people may argue the width of a cyclist is not 1 metre. The measurement is based on the combination of bicycle-with-rider being 750mm, plus an allowance of 125mm of lateral movement (both sides) which is required in normal riding. This gives the operational width of 1 metre, as specified by Austroads. CROW also supports this but has additional lateral measurements depending on the situation.



BUS AND TRUCK MEASUREMENTS

If you're a local government street designer and think you'll take back the 250mm of wiggle-room from the cycling envelop shown above. Not so fast. The widest normal legal vehicle width in Western Australia is 2.5 metres plus mirrors. The specification of 2.7 metres in total width described earlier is a very modest estimate. It includes only 100mm of mirror extending beyond the body of a truck or bus. Depending on the individual vehicle, mirrors could extend 200mm on each side which would increase the total width to 2.9 metres.

Also, the calculation of a 4.7 metre minimum lane requirement has no gap between the large vehicle and the street median. There is no wiggle-room for the bus or truck driver. At a 4.7 metre width, the driver will be required to travel with the edge of the vehicle in line with the kerb of the median.  Where there are trees planted with spreading branches (common in Perth) the larger vehicles would be brushing through branches in order to keep the required legal separation. This rarely happens. The risk of damaging the vehicle by hitting thicker, hidden branches is too great.

Oxford Street Leederville Western Australia
Of course, there are some small trucks and buses. Australia has a wide variety of vehicles, but for the purposes of this guide, where trucks and buses are listed it presumes they are the maximum width.

HOW WIDE IS A CAR?

An average car is around two metres wide. Since the Smart Fortwo has been removed from the Australian market, the narrowest new models currently sold appear to be the Holden Spark and Kia Pinato which are 1595mm plus mirrors. Manufacturers usually specify the width of their vehicles excluding the mirrors. This must have been a tradition from times when external mirrors were a flimsy accessory. On modern cars the mirror housing is usually very solid and needs to be considered a potential threat to other street users. 


It is difficult to find precise information on how much the mirrors add to the width without resorting to individual measurement. Mirror width will vary between manufacturers and even between the production year of the same model. Physically measuring the two Volkswagen Golfs in the list below revealed the mirrors on the 2010 model added 260mm, while on the 2017 model the mirrors added 230mm.

The list shows the estimated total width of a variety of vehicles with a reasonable addition of 200mm for mirrors. The classic Mini has an official mirror measurement of 150mm and the Fiat Bambino is an estimate based on the Mini's smaller mirrors.



HOW THE SEPARATION IS MEASURED

Western Australia's Road Safety Commission website states the "safe passing distance is measured from the furthest point to the left of the driver's vehicle to the furthest point on the right on the bicycle". This summary of the official Road Traffic Act regulation (PDF download) is poorly written because it implies that the person is not important. The RSC omits an important aspect: for the purpose of the Act, the rider is considered part of the bicycle.

WHAT IS MISSING?

The information about lane width here is simplified and only describes one person on a bicycle.  It does not include tricycles, hand-cycles or other types of cycle. The width of these can be up to 1.2 metres. They are an important consideration for any future cycle network design but have not been covered.

Also there are no details about the lane width required for drivers to legally pass two bicycle riders side-by-side. Riding side-by-side is legal on Western Australian streets.

The guide also presumes the person cycling is using the first metre on the left side of the street. At times this will not be possible because of debris near the kerb.

When the left side of the lane is immediately adjacent to parked cars this guide presumes the cyclist to be riding in the 'door-zone' where they are at risk of injury from the car doors being opened. In practice, drivers are likely to encounter cyclists who have defensively positioned themselves away from the parked cars to allow more reaction time. In that situation, car drivers should not attempt to pass at any of the locations listed.

It also presumes drivers have the skill to maintain a position on the extreme right side. The vehicle's mirror would be in line with the kerb, and the tyres almost scrubbing against the kerb.


THE LANE WIDTH GUIDE


This is a selection of streets with narrow lanes. They sometimes have continuous medians often planted with trees. In some situations the medians are not continuous but the close spacing has a similar effect. All these narrow sections are at least 200 metres long. 

Hopefully, this guide will be useful for everyone. For cyclists, if they are passed by a bus or a truck, they will know immediately that an offence has occurred. At the narrowest locations, even a passing car will signal an offence.

For drivers this guide will reduce the worry about passing people at all these locations. Depending on whether they drive a truck, bus or car, people can learn which are the 'no passing' streets.

And for local government it will be a useful tool for monitoring the decline in cycle travel within their areas and as a guide for future design and street repair.


LOCATION 1 - NO PASSING





LOCATION 2 - NO PASSING






LOCATION 3 - NO PASSING





LOCATION 4 - NO PASSING (EAST BOUND)






LOCATION 5 - NO PASSING UNLESS CYCLIST RIDING IN PARKING BAYS






LOCATION 6 - NO PASSING






LOCATION 7 - NO PASSING, UNLESS YOU DRIVE A FIAT BAMBINO





LOCATION 8 - HIGHLY SKILLED DRIVERS OF SMALL CARS MAY BE ABLE TO PASS





LOCATION 9 - ONLY SMALL CARS CAN PASS





LOCATION 10 - ONLY SMALL CARS CAN PASS






LOCATION 11 - CARS CAN PASS BUT NOT BUSES OR TRUCKS





LOCATION 12 - CARS CAN PASS BUT NOT BUSES OR TRUCKS







LOCATION 13 - CARS CAN PASS BUT NOT BUSES AND TRUCKS






LOCATION 14 - CARS CAN PASS BUT NOT BUSES AND TRUCKS





LOCATION 15 - CARS CAN PASS BUT NOT BUSES AND TRUCKS






OPTIONS FOR THE FUTURE


Drivers who are frustrated by the number of places where they are put into conflict may be wondering how to improve the situation on our streets.

A solution, which has been done in several places around the world, is to separate cycling from motor vehicles. Not by a painted lane on the edge of a fairly narrow carriageway. As the guide shows, this does not always work. And not by relegating all bikes to the footpath where conflict can also occur.  

The method is to provide a path for cycling between the footpath and the motor vehicles. A 'third path' where cycling is separated from both the other modes.

  
These cycle paths are not just a footpath with a different colour. To work well they need to be smooth and continuous across intersections. If you want the people on bikes out of your way, they need a quality alternative.


At the intersections with traffic lights, there are also traffic lights for the cycle path. You can read more about the three-mode idea in an earlier blog post.


Trees can still be planted, but not in the middle of the street. They can be put on the sides where they are more beneficial for the people who don't have air-conditioning: the pedestrians and cyclists.  Drivers may be able to park their cars in the shade as well.  If you think this is a good idea, please contact your local government.

Ord Street Fremantle