BRAKING FORCE
DISTRIBUTION FOR ARTICULATED BUSES OF TRANSJAKARTA BUS RAPID TRANSIT
I Putu Alit
Putra / 56-090938-6004-1
ABSTRACT
TransJakarta is a Bus Rapid Transit (BRT)
system in Jakarta, Indonesia.
It was the first BRT system in Southern and Southeast Asia. In
order to increase the capabillity and also capacity of Transjakarta Bus Rapid
Transit, management of Transjakarta prefer to use articulated buses than using
a single bus. Although, there are several
advantages of using articulated buses as BRT, there are also
disadvantages of using this kind of bus. One of the disadvantage that is
sometimes experienced by this articulated buses are the bad braking force
performance because of unbalance braking force distribution. From literature
study it is known that, there are researcher that already publish their result
about braking force distribution but not on the field of articulated
buses. Esmailzadeh et al did research
in the field of optimized braking force distribution during a braking-in-turn
maneuver for articulated vehicles. Here, Esmailzadeh et al using model of truck
as a tractor vehicle with a trailer unit. Peng et al, did the research in the
field of Traction and Braking force distribution for optimal longitudinal
motion during curve following. They are using 4 wheel vehicle model in order to
did the calculation and formula derivations.According to explanation above,
This research will focus on the braking force distribution for articulated
buses that applied as Transjakarta Bus Rapid Transit. This research are
important because TransJakarta BRT often use Articulated. This research will
develop a new approach for Braking force distribution of articulated buses
based on the method that already developed by Esmailzadeh et al and Peng et al.
Hopefully from this research can be achieved the most optimum model for braking
force distribution of articulated buses by combine Esmailzadeh et al method and
Peng et al method.
Keywords:
Articulated buses, TransJakarta BRT, braking force
distribution,slip control, traction force
1.
INTRODUCTION
1.1 The Background to the Study
TransJakarta is a Bus Rapid Transit (BRT)
system in Jakarta, Indonesia.
It was the first BRT system in Southern and Southeast Asia. The TransJakarta
system began operations on January 25, 2004. As of February 14, 2013 the 12th
corridor was added officially, with 3 more currently corridors in progress.
TransJakarta was designed to provide Jakarta citizens with a fast public
transportation system to help reduce rush hour traffic. The buses run in
special lanes and ticket prices are subsidized by the regional government. In
2011 TransJakarta carried around 115 million passengers (about 310,000
passengers per day) which was an increase of 32% the 87 million passengers
carried during 2010. The subsidy per passenger-ticket in 2011 was around Rp
2,900 ($0.29) and for 2012 the subsidy is expected be around Rp 2,100 ($0.21)
per passenger-ticket. Currently TransJakarta has the world's longest BRT routes
(172 km in length) and has more than 669 buses in operation.[1].
In order to increase the capabillity and also capacity of
Transjakarta Bus Rapid Transit, management of Transjakarta prefer to use
articulated buses than using a single bus. As known, Articulated buses are
being used more frequently on popular bus routes, as they can handle high
volume passenger loads. Articulated buses can increase the speed of boarding
and alighting at each stop, as well as reduce the number of buses needed on a
route. Experts recommend the use of articulated buses as part of bus rapid
transit (BRT) systems and express routes [2].
Picture 1. Articulated buses of TransJakarta BRT [1].
Although, there are several advantages of
using articulated buses as BRT,
there are also disadvantages of using this kind of bus. One of the disadvantage
that is sometimes experienced by this articulated buses are the bad braking
force performance. A key aspect of good braking performance is the balanced of
that braking. This occurs when each wheel brakes proportional to the weight
that it carries. If this ideal is achieved then the vehicle can use all the
available road friction and will have the minimum stopping distance without
skidding wheels. Wheel lock-up promotes loss of directional
control,particularly when it occurs on drive or trailer axles, because the
locked wheel cannot provide stabilizing side forces. [3].
There are several ways to control the braking balanced
between the axles like using Load Sensing Proportioning Valve. The load sensing
proportioning valve (L.S.P.V) employed to adjusting braking force among axles
to the normal forces on those axles and closed actual brake force to ideal
brake force distribution. These valves operate based on the static deflection
of the rear suspension, but they are not able to compensate for the dynamic
load transfer between the front and rear axles [4].
Articulated vehicles stability, much likes for cars,
requires that the tractor front axle locks first, and followed by the trailer
axle, with the tractor rear axle locking up last [4]. In the modern braking
systems, such as electronic brake force distribution (EBD) systems, using
sophisticated algorithms formed based on slip control approach; the braking
force distribution is done intelligently leads to higher stability and shorter
stopping distance.
There are several papers that focusing on the braking
balance (braking force distribution) and braking performance of the vehicle
especially for articulated vehicle. But there is no papers that do the research
for braking force distribution for articulated buses because most of that
focusing on truck with trailer unit.
Esmailzadeh et al [4]
did research in the field of optimized braking force distribution during a
braking-in-turn maneuver for articulated vehicles. Here, Esmailzadeh et al
using model of truck as a tractor vehicle with a trailer unit.They are develop innovative approach to formulate a new
braking force distribution strategy for articulated vehicles and also they are
included mathematical optimization proces. The optimized strategy that
Esmailzadeh et al is develop as the
other modern braking force distribution strategies, works based on wheel slip control.
Another researcher that did the research in this field were Peng et al [5].
Peng et al, did the research in the field of Traction and Braking force
distribution for optimal longitudinal motion during curve following. They are
using 4 wheel vehicle model in order to did the calculation and formula
derivations. They did 3 scenario as the variable of research and every scenario
the get the result of the mathematical equations for braking and traction force
distribution.
According to
explanation above, This research will focus on the braking force distribution
for articulated buses that applied as Transjakarta Bus Rapid Transit. This
research are important because TransJakarta BRT often use Articulated. This
research will develop a new approach for Braking force distribution of
articulated buses based on the method that already developed by Esmailzadeh et
al and Peng et al. Hopefully from this research can be achieved the most
optimum model for braking force distribution of articulated buses by combine
Esmailzadeh et al method and Peng et al method.
1.2 The Purposes of the Study
1.2.1 To
develop mathematical formulation of braking force distribution on articulated
buses based on wheel slip control.
1.2.2 To optimized braking force distribution of
articulated buses
1.2.3 To find
the best strategy of braking force distribution on articulated buses that can
be applied on TransJakarta Bus Rapid Transit.
1.3 The Significance of the Study
This study and research are important in order to get
optimum braking force distribution of Articulated buses because there is no
research that focus on this field and also, this research will be useful for
BRT that use Articulated Buses as their primary transportation mode like
TransJakarta BRT.
1.4 Research Questions
1.4.1 How to develop mathematical
formulation of braking force distribution on articulated buses based on wheel
slip control ?
1.4.2 How to optimized braking force
distribution of articulated buses ?
1.4.3 What
is the best strategy of braking force distribution on articulated buses that
can be applied ?
2. REFERENCES
[2] Herbert S. Levinson, Samuel Zimmerman, Jennifer
Clinger,and Scott C. Rutherford. Bus Rapid Transit : On Overview. Journal
of Public Transportation Volume 5, No.
2, 2002 ISSN 1077-291X
[3] National Heavy Vehicle Braking Strategy Discussion
Paper February 2006
[4] E.
Esmailzadeh, A. Goodarzi, and M. Behmadi. Optimized Braking Force Distribution
during a Braking-in-Turn Maneuver for Articulated Vehicles. International Journal of Automotive Engineering Vol. 1,
Number 1, January 2011
[5] Huei Peng , Jwu-Sheng Hu. Traction/Braking Force
Distribution for Optimal Longitudinal Motion During Curve Following. Vehicle
System Dynamics, Vol. 26, No.4, October 1996, pp.301-320.
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