GUIDELINES FOR
PASSENGER TRANSPORT IN SOUTH AFRICA
A MULTI MODAL ANALYSIS
[Transportation 3B – CBTL302]
CHAPTER 11
11. BUSES
11.1 Introduction
Throughout the world, diesel buses are the most widely used (indeed in many cities the only) form of public
transport. Even in South Africa, where the minibus-taxi is responsible for more than half of all public passenger
transport movements, buses are to be found in all the larger cities and in most towns.
Buses have a variety of technical and operational characteristics. Most buses have two axles and a total of six
wheels, but there are models with three axles and up to 10 wheels. Bus capacity, typically about 70, may vary
between about 25 (midibus) and 125 spaces (articulated bus). By far the most common propulsion is by diesel
motor. Electric propulsion from overhead wires (trolley bus) is much less common, while other propulsion
types such as “fuel cell” and “compressed natural gas”, are used only exceptionally; although their use is on
the increase.
The vast majority of buses operate on streets, in mixed traffic. A small, but increasing number of cities have
reserved and separated bus lanes for heavily travelled routes. The highest category is the busway, a roadway
used exclusively by buses.
Bus vehicle classifications are based on propulsion and vehicle type (size), bus modes are based mostly on type
of service, but are seldom precisely defined.
11.2 General Characteristics of buses
(a) Ability to operate on most streets exists because buses contain their own power plant (except trolley
buses). It gives buses several major advantages over other public transport modes. Their routes can be
placed on any street, as demand requires and other factors permit. Their stops can be placed at many
points. Temporary reroutings are also relatively easy. On the negative side, the ability of buses to mix
with other traffic makes it more difficult to separate buses where their operation would require such
treatment than is the case with guided modes. Because they “blend” with other traffic and their routes
have no fixed facilities, diesel buses have a weak identity and image.
(b) Low investment cost: minimal route infrastructure makes rapid introduction, changes, and extensions
of bus routes and stops easy. Buses are ideally suited for use on experimental routes, temporary
services during rail construction, promotional routes, and so on. Low investment, on the other hand,
results in low permanence and usually little influence of (diesel) bus lines on land use and urban form.
(c) Moderate capacity transport units (TUs) make buses the ideal mode for lightly to moderately travelled
public transport routes. For services that require TUs with capacities of 15 to 60 spaces, buses are
usually the most economical mode. However, when passenger volumes are high, buses become
uneconomical because of their limited vehicle capacity.
11.3.1 Classification by propulsion systems
A number of different propulsion systems have been used for buses, but only two have broad application today: the
diesel motor (diesel bus), also popularly referred to as “motorbus”, and electric motor (trolley bus).
(a) Diesel buses
superior characteristics: ruggedness, simplicity, economical operation and easy maintenance.
Disadvantages of exhaust, vibration and noise production.
Recent models have been produced which have greatly reduced negative effects: some of them meet rigorous air
pollution standards, produce low noise levels, and have very little vibration.
(b) Trolley buses / Duo-buses
They are electrically powered vehicles which obtain power via trolley poles from two overhead wires (+ and -). Trolley
buses are the only rubbertyred highway vehicles without a self-contained power source for regular operation. They have
the excellent operating characteristics of electric traction: rapid and smooth acceleration and deceleration, no noise or
exhaust fumes, low vehicle maintenance costs and high durability. However, they require a higher investment and line
maintenance cost.
“duo-bus” technology (i.e. a bus with an electric motor as well as a diesel motor) and next chapter of this study guide
will refer to the concept.
11.3.2 Classification by type of body
(a) Standard single-deck bus
The most common type of bus (and trolley bus) is a single-deck body with two axles, six wheels and a capacity of
50 - 60 seated passengers. The allowance for standing passengers can vary from 0 to 50 depending on
circumstances. A few single-deckers
(b) Articulated bus
Briefly stated, an articulated bus, compared with a standardbus, provides:
+ Higher line capacity.
+ Higher labour productivity (lower cost per space-km).
+ Similar geometric movement characteristics.
- Sometimes lower acceleration and climbing abilities (depends on motor power).
- Lower riding comfort, particularly in the rear section.
- Somewhat lower stability at high speeds and/or in sharp turns.
Consequently, the main factors for their introduction are required capacity and operating costs per space-km: their
inherent advantage over standard buses in both of these makes articulated buses the best vehicles for heavily travelled
routes.
Double-articulated buses (i.e. consisting of three sections) are now coming into increased use, mainly in reserved busways in Latin America.
(c) Double-decker bus
Compared with single-deckers, double-deckers have the following advantages and disadvantages:
Double-deckers, compared with standard buses, have:
+ Higher capacity, particularly seating, for the same vehicle length.
+ An attractive view for passengers on the upper deck.
+ Little disturbance on the upper deck from passenger movements, particularly useful for longer trips.
- Greater vehicle height, requiring higher clearances.
- Inconvenience of ascending and descending the stairway during bus movement.
- More difficult supervision of the upper deck (possible by driver via a periscope).
- More constrained passenger circulation, making doubledeckers less convenient for routes with heavy passenger
turnover.
(d) Midibus
The midibus is a 5 to 7 metre long vehicle with a total capacity of 20 to 35 passengers. (It can accommodate standing
passengers, which minibus-taxis cannot). There are no trolley buses of this type.
In 1999, the South African Government announced a large ‘recapitalisation” programme to replace minibus-taxis with
midibuses. This programme, which involved an initial funding of R3,2 billion, (later raised to R8 billion) is discussed in the
chapter on minibus-taxis.
11.4 Diesel Buses - Some Operational Issues
A matter of serious concern in South Africa is the decline in market share (in terms of the journey-to-work) of the bus
mode, from 12% to 9% between 1998 and 2003. This decline has had serious implications for the economic well being of
our cities, as it has resulted in higher levels of traffic congestion, longer journey times and higher costs in general.
This section will briefly review some of the factors relevant to the problem. They include:



The image of bus operations in general
Environmental characteristics
The poor organisational performance of bus management
11.4.1 The image of bus operations in general
This places them at a disadvantage because the communities that they serve take them for granted and regard them as
part of the ‘street furniture”. The fact that they also operate virtually everywhere under category C conditions reduces
their operational performance.
The light rail studies referred to in the previous chapter (para 10.8) emphasised the low image of (diesel) buses.
In addition to the noise problem is the effect of gear changing, (this also applies to buses fitted with automatic gears)
which is always accompanied by a change in engine pitch.
11.4.2 Environmental characteristics
This may also be due to other factors such as the presence of litter, beggars and a lack of security, but the presence of
diesel buses with their revving engines and overpowering exhausts does nothing to raise the environmental standard of
the area.
11.4.3 The poor organisational performance of bus management
Chapter 3 of this study has already referred to the ineffectiveness of transport management and its general lack of
enthusiasm for promoting the cause of public transport. One of the factors has apparently been that for many years the
bus industry has been a target for subsidy cuts.
These seem to have demoralised bus transport managers to a certain extent and have lead to reductions in service and a
tendency to buy the cheapest vehicles or to rebuild older ones. This has in turn led to lower standards of services and a
low opinion of public transport in general.
11.5 Diesel bus developments and improvements
In response to both local and overseas criticisms and comments, diesel bus manufacturers have raised quality standards.
Many new developments have shaped the modern diesel bus. These have included:
•
•
•
•
•
•
•
•
modular concepts
combination of different materials
low-floor construction
improved shapes
more comfort features
driving position with better ergonomics
more safety features
new motive power solutions.
Going modular has also made it easier to meet the requirements of different customers.
Most buses and coaches are now characterised by innovative combinations of steel (which is now less than 50% by
weight), plastics (front and rear end, roof), aluminium (doors) and other materials.
Low-floor construction was originally demanded by mothers with push chairs, elderly and handicapped people. But lowstep heights also speeds up the loading and off-loading of passengers, allowing operators of urban bus services to use
fewer vehicles and drivers.
Today’s bus passengers also enjoy increased comfort. Seats now provide better seats and backrest support while
ticketing and other passenger aids are now all within easy reach and information systems have been greatly improved.
Exhaust emissions have also been considerably reduced in recent years. Recent developments also include the use of
fuel-cell technology in buses in a number of cities throughout the world.
11.6 Conclusion
This study suggests that while technical improvements to diesel buses, such as quieter engines, automatic gears and
other refinements are desirable, in themselves they will not solve the problems of the mode. A holistic approach is
necessary, in terms of which the role of diesel buses should be seen within the context of a hierarchy of modes,
including heavy and light rail, and trolley/duo-buses. Better frequencies, many new routes and better marketing are also
required. This study suggests that the presence of high-image modes in an integrated system will help to improve the
image of the diesel bus component. To this end, the role of trolley buses and duo-buses should receive attention from
planners and operators. This is an area which has been neglected up to now.