traffic calming measures and bus traffic

7/27/2019 Traffic Calming Measures and Bus Traffic

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BackgroundIt is particularly critical in residential areas, where it has contributed to

an increase in road accidents. The increase in traffic using residential

roads to avoid congested main roads has to be countered in order to

protect the interests of pedestrians, cyclists and residents.

UITP strongly supports the introduction of traffic calming measures in

cities. However, it is necessary to continue to provide bus services to

all areas of the city in order to maintain the quality of life. So UITP

also wishes to ensure that buses can negotiate traffic calming schemes

in a satisfactory manner, and where possible that measures to favour

public transport should be included in new schemes.

What do we mean by traffic calming measures ?

In general, traffic calming includes all measures taken to reduce the

speed of vehicles, often to achieve a 30km/h (20 mph) zone. It includes

a range of methods such as the use of different surface materials (for

example paving stones instead of macadam), road narrowing, humps,

chicanes, roundabouts, speed cushions, raised junctions, or any

combination of them. In general, traffic calming measures can be

categorised into vertical or horizontal obstacles.

Road narrowing and roundabouts are the most common horizontal

obstacles. Due to the width of buses, a horizontal measure that

provides traffic calming for cars can make passage difficult for the bus.

However, if the width of the obstacle is adapted to suit buses, the

calming effect can still be achieved for smaller vehicles. Small

innovative design features can be very effective in achieving this:

- A street may be narrowed just at the bus stop.- It can be on one or two sides of the stop, in the shape of a nub

or hourglass.

Union Internationale des Transports Publics

International Association of Public Transport

Internationaler Verband fr ffentliches Verkehrswesen August 2002

CORE BRIEFTraffic calming measures and bus traffic

A Core Brief is a UITP information sheet English version

In recent years, trafficcalming measures havebeen introduced in mostcities in order to reducethe speed and volumeof traffic in residentialareas. The growth oftraffic has indeedaffected the whole road

network frommotorways to minorrural routes.

Speed cushion


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The principal types of vertical obstacle are speed

cushions, and sinusoidal and trapezoidal humps

(including raised junctions). These vertical traffic

calming measures can cause damage to buses - indeed,

they are normally designed to calm cars but not buses.As a result, they can cause discomfort and backache

for bus passengers and/or drivers, and damage to the

suspension of buses whilst slowing down bus travel. If

the design of the traffic calming does not

accommodate the needs of buses, then the scheme can

reduce the attractiveness of public transport, which is

not the objective.

In order to avoid such situations, UITP presents in this

Core Brief some guidelines to help the design andimplementation of traffic calming measures. These

guidelines are based on actual experience and case

studies in a number of countries.

A Safer Environment with Traffic

Calming

In 1999, more than 45,000 people were killed in road

accidents in the 15 European countries, and almost 1.4million were injured. Traffic calming measures are,

therefore, essential for road safety, and they also

introduce a more friendly environment in public

places.

By reducing vehicle speeds, traffic calming measures

also have other positive effects, improving the quality

of life by:

Reducing the volume of traffic passing

through the neighbourhood; Reducing air pollution as emissions are greatly

reduced at 30 km/h;

Reducing noise levels.

It is particularly important to reduce traffic speeds near

schools, in order to ensure the safety of the children,

who are particularly vulnerable to accidents. Children

could then walk to school instead of being taken by

car, which would further reduce traffic levels.

The most successful traffic calming measures aredesigned as part of an overall environmental scheme

intended to improve the quality of life in a

neighbourhood or even across the whole city. They

should therefore not be designed in isolation but as part

of an integrated sustainable mobility or urban plan,

part of a global vision for the development of the area

as a whole.

They will then form part of a package alongside other

measures such as improvements to public transport,signage, parking policy, cycle paths, pedestrian

walkways, etc. The use of different surface materials

forming a harmony together is also an important

factor. The city of Bruges provides a good example as

there are no speed humps in the centre, and yet it is

unusual to see a car driven faster than 30 km/h. The

combination of narrow streets, old paving stones and

substantial bicycle traffic slows all the traffic in a

natural manner.

This demonstrates that horizontal obstacles appear to

have most to offer in urban areas as they improve the

outlook of the whole street and give more space to

other users.

Of the vertical obstacles, the raised junction is

particularly recommended as it also has the effect of

narrowing the street. This reduces the traffic speed at

the crossroads but also enables an improved pedestrian

crossing to be provided, especially for handicapped

people, and when ears are included it prevents illegalparking.

Characteristics of some vertical

deflections

The impact of a traffic calming measure on bus traffic

depends not only on the design of the obstacle itself

but also on the type of bus (low-floor, articulated, etc).

Due to the large variety of bus types and traffic

calming measures it is not possible to consider all the

possible combinations. It is therefore important to

Nub bus stop


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involve all the organisations involved at an early stage in development of

a scheme to ensure that all the issues are considered.

An example of this is the city of Toulouse in France, which has created a

system of global traffic management (Systme de gestion globale des

dplacements). All the authorities, traffic operators and road

administration managers are now working together in the same buildingto increase dialogue and co-operation.

Speed cushions A speed cushion is an elevation of the middle portion of the traffic lane.

As buses have a wider wheel track width, they can straddle the cushion

without being affected. However, cars have to drive over the obstacle

to get across. Ideally the minimum width should be 100 cm and the

maximum 120 cm.

Sinusoidal hump A sinusoidal hump is a short circular elevation of the street. Its

effectiveness depends on the height, the gradient of the ramp and the

distance between adjacent humps. Humps are more effective the

shorter the ramp. However, as the hump takes the whole width of the

street it also affects buses, and so these should be avoided on bus routes

- this is recognised in the traffic regulations of France and Belgium.

Plateau hump As its name suggests, the plateau hump is a hump with a flat

top. A particular type is the raised junction, which alsooffers an easier pedestrian crossing, especially for disabled

people as it is shorter and at the same level with the footpath.

Plateau humps or trapezoidal humps are also easier for

cyclists. For buses, the plateau length should not be less than

the longest wheelbase of the bus types used on the route.

In order for the ramps to be effective, the height should be

between 8 and 12 cm with a ramp of maximum 4%. This

can be passed by a bus at speeds up to 20 km/h. To further

distinguish the hump, its surface could be similar to the

footpath and different from that of the carriageway.

Removable bollards These bollards lower into the ground on the approach of authorised

vehicles such as buses, emergency services, etc. This system is

particularly helpful to buses as they are able to use streets which are

prohibited to normal car traffic.


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This Core Brief has been prepared by the General Commission on Transport and Urban Life.

UITP, International Association of Public Transport

rue Sainte Marie 6 B-1080 Brussels Belgium Tel +32 2 673 61 00 Fax +32 2 660 10 72

UITP Guidelines

UITP strongly supports the introduction of well planned traffic calming measures into the city

landscape in order to improve the environment and quality of life.

In general, UITP proposes that :

At the earliest possible stage of development of a traffic calming scheme, all the actors should be

consulted, and participate in the design of the scheme. This includes the authorities, public

transport operators, road administration managers, emergency services, etc.

Traffic calming measures should form part of more global environmental and mobility plans.

Horizontal obstacles are preferable to vertical ones on bus routes, and their design must take into

account the design of the buses used on that route, including their length, width, and turning circle.

Some horizontal measures in fact assist bus traffic, including the nub bus stop and hourglass bus

stop.

Wherever vertical deflections have to be used, UITP recommends the following guidelines:

Speed cushions are preferable to full width humps on bus routes. A maximum width of between

1.0 and 1.2m is recommended so that buses can straddle the cushion.

If used, road humps should be the extended flat top type. Raised junctions with pedestrian

crossings are recommended as the best measure from an overall town-planning point of view.

The plateau length should not be less than the longest wheelbase of any public service vehicle

likely to use the road, usually 8 metres.

The hump height should not exceed 12 cm and the access slope should be between 3 and 4%.

Of course, these guidelines remain general. They must be adapted to the local situation and the type

of bus running.

traffic calming measures and bus traffic

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