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SCHOOL OF HOUSING, BUILDING AND PLANNING, SESSION 2011/2012
TO EXAMINE THE POTENTIAL OF
LAND USE UNDER FLYOVER IN THE
ASPECT OF SAFETY
RPG 131-APPLIED QUANTITATIVE
METHODS

2. LECTURER: DR. NORAZMAWATI MD. SANI @ ABD. RAHIM
SUBMISSION DATE: 27TH MARCH 2012
MEMBERS OF GROUP 18:
1. NG CHOO LIANG 110675
2. NEO JUN CHEN 110674
3. CH’NG SEE KEE 110608

3. TABLE OF CONTENT
1. TITTLE
2. ABSTRACT
3. INTRODUCTION
4. RESEARCH PROBLEMS
5. RESEARCH QUESTIONS
6. RESEARCH OBJECTIVES
7. RESEARCH FRAMEWORK
8. LITERATURE REVIEW
9. RESEARCH METHODOLOGY
10. ANALYSIS
11. RESULTS
12. DISCUSSION
13. CONCLUSION
14. REFERENCES

4. 1.0Title
Development under Flyover in aspect of Safety
2.0 Abstract
Land use practices vary considerably across the country. Land use and land
management practices have a major impact on natural resources including water, soil,
nutrients, plants and animals. Land-use planning is the term used for a branch of public
policy encompassing various disciplines which seek to order and regulate land use in an
efficient an ethical way, thus preventing land-use conflicts. Land-use planning often
leads to land-use regulations, also known as zoning, but they are not one and the same.
Zoning regulates the types of activities that can be accommodated on a given piece of
land, the amount of space devoted to those activities and the ways that buildings may be
placed and shapes.
We also should consider the aspect of safety regardless of what type of building
that we are built. There are two slightly different meanings of safety. For example,
home safety may indicate a building’s ability to protect against external harm events
(such as whether, home invasion, etc), or may indicate that its internal installations
(such as appliances, stairs, etc) are safe for its inhabitants. Discussions of safety often
include mention of related term that is security. Security is the process or means,
physical or human, of delaying, preventing, and otherwise protecting against external or
internal, defects, dangers, loss, criminals, and other individuals or actions that threaten,
hinder or destroy an organization’s “ steady state,” and deprive it of its intended purpose
for being.
We may build highway under flyover. Traffic light is important to increase the
aspect of safety. Besides, developers can build a car park to utilise the land use under
flyover. Futsal Park is a good suggestion to build under the flyover. Informal markets
spring out selling chicken, fish, and fruit. There is still having many potential of land
use under flyover such as pocket parks, cycling path, night shelter and newspaper or
reading kiosks. In this report, we’ll discuss about what type of development can be built
under the flyover and also discuss the development in aspect of safety.

5. 3.0 Introduction
Firstly, flyover refers to a high-level overpass that crosses over a highway
interchange or intersection. Land use is the human use of land. Land use involves the
management and modification of natural environment such as fields, pastures, and
settlements. Lands under flyover are usually left empty and we may build a car park on
the land, but we should consider it in aspect of safety. Therefore, the purpose of our
research is to examine the potential of land use under flyover in the aspect of safety.
Safety is the condition of being protected against physical, social, spiritual,
financial, political, emotional, occupational, psychological, educational or other types or
consequences of failure, damage, error, accidents, harm or any event which could be
consider non-desirable. There have several types of safety. Normative safety describes
products or designs that meet application design standards are met. Besides, substantive
or objective safety means that the real-world safety history is favourable, whether or not
standards are met. Lastly, perceived or subjective safety refers to the level of comfort of
users. For example, traffic signals are perceived as safe, yet under some circumstances,
they can increase traffic crashes at an intersection. So, we should taking safety
precaution before building a car park under flyover.
There are a lot of developments that we can do under the flyover if we didn’t
take safety into account as one of the suitability factor. But the reality is, whatever the
development projects it is going to be, safety always comes first. Hence, the potential of
land use under the flyover needs to be consider seriously in the aspect of safety as it
might involves up to hundreds of human’s life. Safety is not only covers the safety of
the people under the flyover, it also covers the people above the flyover and the people
around the flyover. Thus, safety is always a big issue when comes to a development
project and we need to find the potential of land use under the flyover from the main
aspect.

6. 4.0 ResearchProblems
For the past 10 years, flyovers in Kuala Lumpur have obvious increment in
numbers which implies the areas occupied by the flyovers are also increasing. With the
rapidly growing development in the Capital city for the past 10 years, the land now
becomes scarce and limited. When the area occupied by infrastructure is increased then
the land now has become lesser and lesser. However, the land under the flyover is left
empty and undeveloped. This is because from the aspect of safety, nothing should be
build under the flyover because it might decrease the stability of the flyover itself.
Now, due to the scarcity of land in the Capital city, every inch of the city is
needed to be utilizing to the fullest. Then the first thing that comes into people’s mind is
to use the land beneath the flyover as it is empty and there are plenty of them almost
everywhere. Therefore, they need to re-consider the land use under flyover in the aspect
of safety again. Even though the land is empty but the potential of land use now is still
under planning phase only. This is because the flyover itself varies from its function and
there are some specific requirements for each function. For instances, the requirements
for flyover of public transport differs from the flyover of KTM or LRT trains.
Assuming the permission to build structures under the flyover is granted, and
then now we will have some lands to use for development. It will help to reduce the
price of the surrounding land by a little bit. On the other hand, it’ll also provide more
opportunity for jobs in the city. Imagine now you can build kiosks under the flyover and
you don’t need to purposely find an empty land for the kiosk along the roadside then
you’ll see how good it is. Land is one of the most important things in a city, the more it
is, the better it’ll be.
Therefore, in short, the potential of land use under the flyover is needed to be
considering seriously in the aspect of safety whether to the people beneath it or to the
flyover itself. In order to give the permission to build any structures under the flyover,
the engineering department of local authorities will need to evaluate the safety of the
structures and the effect of the structures to the flyover.

7. 5.0 ResearchQuestions
i. What kind of development that can be proposed under the flyover?
ii. What are the requirements or specifications of structures that are going to build
under the flyover?
iii. Which structures are suitable to be built under flyover without affecting the
stability of the flyover?
iv. Are the people under the flyover is safe from the traffics on the roads beside it?
v. Will the development under the flyover increase the traffics on the roads beside
it and contribute to the accident rate?

8. 6.0 ResearchObjectives
The proposed study has been designed to attain following objectives:
 To identify the potential of land use under the flyover.
 To determine whether the development under flyover will affects the stability of
the flyover itself.
 To determine whether the people under flyover will face any form of harm from
the surrounding.
 To determine whether the development under flyover will affects the traffics
around it and lead to increase in accident rate.

9. 7.0 ResearchFrameworks
To build a new and relevant research activity on examine the potential of land
use under flyover in aspect of safety, we need to have a good understanding of what we
wanted to know through this research and the appropriate research approaches in order
to produce a new knowledge.
A research framework defines the categories of independent variables and
dependent variables. Thus, in our research, our independent variable is to examine the
potential of land use under flyover whereas our dependent variable is the safety of the
development.
To examine the potential of land use under flyover is the independent variable as
we are free to choose what development we are going to discuss. Whereas the safety of
the development is the dependent variable as it is the primary interest to the researcher
(main issue). The dependent variable will respond to the independent variable in order
to get the results of this research.
In our research, the safety of the development is divided into 3 parts. The first
and the most important part is the effect of the development to the stability of the
flyover itself. For example, if the development requires a lot of drilling or piling, then
it’s not suitable to build under the flyover as it will weaken the strength of the
supporting posts throughout the whole construction period.

10. Then, the second part is the risk faced by the people if activities are carried out
under the flyover. Example, if the futsal court is being built under the flyover, is it safe
to be used? And will it be safe from the harm of the traffic beside the flyover? The last
part in the safety aspect is the effects on the traffic around the flyover after development
and will it increase the accident rate. For instances, after the development, will it
obstruct the traffic on the road beside it? Is there any increase in chance for accident to
be occur?
After all, the development should not be permitted if that will bring harm to the
flyover, to the people under the flyover or to the road user surrounding the flyover.
Safety is still the biggest concern among all the factors.
8.0 Literature Review

11. In most of the time, the land under flyover is considered dirty and dangerous.
There are not seen to be managed well by most people. But, this need not be so. We see
the space under the flyover as having wonderful potential. It is sheltered from the rain
and from the heat of the sun. Amazingly, it is also free of much of the politics, land
tenure disputes and real estate speculation that plague much of Bombay. The flyover
itself was proposed as necessary civic infrastructure. Why can’t this idea be extended
below as well?
In Mumbai, there is a flyover at Crawford Market area all the way to Byculla,
called JJ flyover. A team of developers, which are Stephanie Carlisle, Ankit Savla,
Sourav Biswas and PriyankaTalreja see the potential under the flyover and had planned
a project which to transform these small space under the flyover into places for play, for
shelter, for community building, for workship and for celebration, instead of parking
slots.
Figure 8.1: Proposal of developing the space under JJ flyover by a development team.
In Singapore, there is a futsal, or indoor soccer, under the Thomson Flyover. It is
a pilot project by the Singapore Land Authority to see how more of such land can be put

12. to better use. We should take some actions to think the way on how to fully utilize the
land without producing any negative impact to the public. For example, Singapore is a
land-scarce location, so it's good to increase the land utility under flyovers.
Figure 8.2: Futsal under Thomson Flyover, Singapore.
In Sydney Australia, parts of Darling Harbour have recreation and garden space
under flyovers. Specific uses include kiosks, public toilets, an interactive water feature,
a lawn area for kid's play. There may even be some retail space under the flyover on the
eastern side of the site.

13. Figure8.3: the freeway passes right over the commercial area of Darling Harbour.
Development means look into every details. We often see that there is lack of
proper management of the area under the flyovers. It is a bit messy and dirty, because
this issue is always ignored by most of the people. In fact, there is a very good potential
to develop the area under the flyover. A developer should fully utilize the land so that it
can bring benefits not only in the aspects of income, but also to the public, environment
and to the country.

14. 9.0 ResearchMethodology
The research is carried out to examine the potential land use under flyover in
aspect of safety. By examining the various ways of land use under flyover in existing
cases, analysis on the safety and functional of the structures under the flyovers are
highlighted. At the end of the analysis, the criteria of a structure under the flyover in
safety aspect are listed out to be discussed and elaborated in the related sections. There
is a few of methodologies that we have used in the research. There are as follow:
a) Reference sources
The main sources of the research information are the Internet, books,
newspapers, magazines and other reading materials. We have found some information
about land use under flyovers in other countries through these resources. For an
example, we found that there is a futsal, or indoor soccer, under the Thomson Flyover in
Singapore. Fundamentally, this is a qualitative research whereby the project’s focus is
on the law, rules and regulations of land use under flyovers, ways to fully utilize the
empty space under the flyovers, and also the aspects of safety that the development of
free land under flyovers that can bring to public.
b) Observation
Besides, the research is also carried out through observations on the existing
cases in nearby area. Our group members have visited to Bayan Lepas Flyover to
identify the current ways of land use under the flyover at that particular area. It is
located in front of the Penang International Airport. The flyover allows traffic to bypass
the airport between the Bayan Lepas town and the free trade zone.

15. Figure 9.1: Picture shows the Bayan Lepas Flyover in Penang Island.
During observation, we found out that traffic congestion was a serious problem,
especially on Friday after office hours from the Bayan Baru flyover at Jalan Sultan
Azlan Shah to the traffic light junction at Jalan Sungai Nibong. The area under the
flyover is not fully utilized as well. There are, sometimes see some cars parking over
there, and some people selling things at there.
c) Conversational Interview
The qualitative research interview seeks to describe and the meanings of central
themes in the life world of the subjects. The main task in interviewing is to understand
the meaning of what the interviewees say. (Kvale, 1996). In conversational interview,
no predetermined questions are asked, in order to remain as open and adaptable as
possible to the interviewee’s nature and priorities; during the interview the interviewer
“goes with the flow”. Some examples of questions to be asked are:
 What is the potential of land use under the flyovers in Malaysia?
 How is the aspect of safety affect the design of structures under flyovers?
 How to improve the safety of public by developing the infrastructure
under flyovers in Malaysia?
The research methods that are used enabled us to gather a vast amount of
information regarding the research problems. In order to provide the reader a clearer
view, all the inputs are carefully analyzed and systematically sorted.

16. However, the lack of quantitative data in the report is something we would like
to note about. An improvement to the research methods would be distribution of survey
forms and interview with the respondents so that first-hand statistical data would be
available to support the research findings.

17. 10.0 Analysis
After we have done the research, we could list out the different ways of
developers on how they utilize the space under flyovers in other countries. Based on our
observation, we can said that most of the space under flyovers are used as car parks and
gardens, but there have some different cases, like in Singapore, there is a futsal, or
indoor soccer, under the Thomson Flyover. There are still many ways people fully
utilize the land under the flyovers. Based on the data gathered, lands under flyovers can
use as:
• Small gardens,
• Car parks,
• Futsal field,
• Advertisement boards,
• Emergency centres.
• Public toilets,
• Garbage dumpsites.
For every case, the pros are we can fully utilize the land in order to save the land space,
and of course for earning purposes in some cases. Build a small garden under flyovers
can beautifying the landscape, reducing the pollutant in that area and regulate the
temperature of the surrounding. Developing emergency centres and public toilet can
bring convenience to the public. By the way, any development under the flyover will
give more or less negative impact, especially in the aspect of safety.
Unlike the small area countries, like Singapore, Malaysia has a wider land to
develop futsal field compare to those countries that only have limited land, because
most of the lands were used for housing and commercial purposes to fulfil public need.
Build a futsal court under flyover is not safe for public, in more or less. Since the place
is just near the road, usually the frequency of vehicles passed by is high. Accidents may
occur anytime; hence the safety of the players may be affected. Besides, it is not

18. strategy enough to place a futsal field under the flyovers. The noise of vehicles, and the
pollutants that produced by those vehicles may affect the health of the players.
Imagine that the space under the flyover is used as a garbage dumpsite, there
will be rodents running around the area, this will increase the chances of accident in
road to occur. Pests like flies will reproduce rapidly and may affect the health of the
residents living nearby. Mosquitoes are likely to reproduce there as water may be
collected inside the garbage after rain. This will increase the risk of an outbreak of a
pandemic like malaria, a disease spread by the Aedes mosquitoes. In addition, the bad
smell of the garbage dumpsite may affect the daily life of public.
In aspect of safety, emergency centres and public toilets are not suitable to be
built under the flyovers as well. The live load and dead load above the structure of the
emergency centres and public toilets are too heavy, since many cars will pass by the
flyover. This can make the structure unbalance and tends to collapse. Moreover, the
siren from the emergency centres may disturb the residents near around.
Last but not least, having a small garden under flyovers will be the safest
method to utilize the land. By developing the small garden under the flyover, the safety
of public, pedestrians and driver will not be affected. It also will not cause the structure
to collapse. The most important thing is that the environment is conserved if the small
garden is built, since sustainable development is the main concern to the construction
field nowadays. It will be a place for passer-by to take a rest at the park, and the plants
at the parks will be provide the fresh air at the surrounding area while improving the
town’s landscape which can attract more tourists.

19. 11.0 Results
Based on the conversational interview that our group members have done to the
public, the results of the public think the most suitable development under flyover in
aspect of safety are shown below:
In one hundred people that we had interviewed, more than half of them (fifty-
two out of one hundred people that interviewed) have proposed that develop a small
garden under the flyover is the most suitable way in the aspect of safety. On the other
hand, three out of one hundred respondents think that by developing an emergency
centre is the most suitable way in aspect of safety, which is the least amount of people
think in this way. This imply that most of them agree that by developing an emergency
centre is not safe to people.
Based on the results shown, developing small garden under the flyover is
seemed to be the most suitable solution in aspect of safety. It is not only environmental
friendly, but also brings lots of benefits to public.
52%
21%
5%
12%
3%
7%
The Potential of Land Use Under Flyover In
Aspect of Safety
Small Garden
Car park
Futsal field
Garbage dumpsite
Emergency centre
others

20. 12.0 Discussion
Malaysia has increasing numbers of flyover day by day; therefore the land use
beneath the flyover has gained more and more attraction day after day. The main
concern of this research is to evaluate the safety of the development under the flyover.
Currently, most of the flyovers are owned by the government or the PLUS Expressway
Berhad. If the flyover is the tracks of the trains, most probably it’ll be owned by
MyRapid or KTMB. The owner of the flyover owns the land too. Then proposal of
development projects not only needed to submit to the local authority but also the owner
of the flyover. This is because they need to evaluate whether this development will
affect the activities on the flyover and will the development affects the stability as well.
There are several types of development projects that are proposed under the
flyover. The examples are gardens or parks, futsal court, parking lots, garbage dumpsite,
emergency center and etc. All of these developments mentioned above is only consists
of mild construction process which doesn’t really involves much changes or vibration to
the land. Thus, most probably these developments will get their development permit as
it is not affecting the stability of the flyover and to the surrounding.
The most important thing in safety is the stability of the flyover. If the stability is
not conserved, then it’ll not only affect the user of the flyover, it’ll also endanger the
people under the flyover. Below are the explanations and ways to calculate the stability
of the flyover.
Internally stabilized soil retaining systems are also known as Reinforced earth
systems. They stabilize the soil mass by introducing tensile reinforcing elements such
as geosynthetic, steel straps, or soil nails into the backfill soil. It receives local support
(reinforcing) from the closest reinforcement as soon as any local yielding occurs; the
local yielding is confined by the nearby reinforcement before it develops into major
yielding of the entire backfill soil.

21. Figure 1. Reinforced Earth Retaining wall
1.1 Advantages (Sharma et al.,1996)
 Flexibility – RE walls distribute loads over compressible soils, reducing the
need for deep foundations.
 High load-carrying capability, both static and dynamic- Applied structural
loads are distributed through the compacted granular fill and earth pressure
loads are resisted by the gravity mass.
 Ease and speed of installation - Prefabricated materials and granular soil
simplify construction.
 Pleasing appearance - Panels may be given a variety of architectural
treatments
 Economy -15-50% savings over cast-in-place concrete walls, depending on
wall height and loading conditions.

22. 1.2 Brief description of Flyover project
As a part of traffic improvement scheme in Pune, flyover at Agriculture college road
has been planned to improve the capacity of a junction. The junction collects traffic
from Shivajinagar, F.C. Road and University Road. The project consists of a dual two
lane flyover from Agriculture College to University Circle for a length of
approximately 0.6 km. The elevated section of the flyover consists of prestressed
concrete deck of 16.4 m wide. The structure is divided into one unit of 400m consisting
of 6 spans of 35.5m and two ramps. At the starting phases of the work the detailed
drawings including L-section, typical cross-sections at various chainage, materials
properties were studied thoroughly and understood. The project involves the provisions
of earth fill of height ranging from 3.5 to 7m.
a)Soil properties:
o Retained backfill soils – γb = 20.00 kN/m3, φb =340
o Reinforced backfill – γr = 20.00 kN/m3, φr =340 (materials less than 15%
passing 75 micron, Cu=3.2)
o Foundation Soil – γf = 20.00 kN/m3, φf =300 (drained condition)
(Soil mix with gravelly silty sand up to a depth of 4.80m)
b) Geogrid: ACE geogrid are continuous grid structures with oval apertures.
c)Seismic data- Seismic zone III, max. Ground acceleration 0.16 [IS 1893 (Part
1):2002]
d) Traffic surcharge = 24.00 kN/m2
e)Parapet loading = 12.00 kN/m
f) Design Life = 100 years

23. 2 Long Term Stability of RE wall
Stability is assured by providing a reinforced granular mass of sufficient dimensions
and structural capacity, bearing on adequate foundation material, having a durable
facing material, well-chosen drainage systems, and proper embedment of the toe of the
wall. Reinforced soil Earth structures are evaluated for external stability, internal
stability, wedge stability and seismic stability. Each type of stability will be discussed
separately. The static design is based upon the principles in BS8006: 1995.
2.1 External Stability
The Reinforced soil -geogrid volume is assumed to act as a rigid block, subject to the
conventional retaining wall failure mechanisms such as: Sliding, Overturning and
Bearing Capacity failure. The External stability comprises of evaluation of the base
width ‘B’ required for height ‘H’ of the wall. It is necessary that minimum factor of
safety of 2 against overturning, 1.5 against sliding and 2.5 for Bearing Capacity failure
(FHWA-NHI-00-043).
i) Factor of safety against overturning (FOS1) = MRO / MO
MRO = Resisting moment against overturning, MO = Overturning moment
ii) Factor of safety against sliding (FOS2) = ∑PR /
∑PD
= qult /
σV
Iii Factor of safety against Bearing capacity of
foundation soil. (FOS3)
qult = Ultimate bearing capacity of foundation soil,
σV = Maximum bearing pressure.

24. Table 1. Factor of safety with respect to wall height.
Sr.
Height of
wall H
Theoretical
width
FOS1 FOS2 FOS3
Adopted
(width)‘B’(m)
No (m) ‘B’(m)
1 3.5 2.45 3.081 1.403 3.357 2.50
2 4.0 2.80 3.246 1.529 3.511 2.80
3 4.5 3.15 3.387 1.636 3.640 3.20
4 5.0 3.50 3.509 1.729 3.750 3.50
5 5.5 3.85 3.616 1.809 3.845 3.90
6 6.0 4.20 3.710 1.879 3.928 4.20
7 6.5 4.55 3.793 1.940 4.000 4.60
8 7.0 4.90 3.550 2.030 3.910 5.00
The practice is to provide minimum value of ‘B’ as 0.7 H but not less than 2.45m
(BS8006: 1995).

25. 2.2 Internal Stability
Internal stability design consists of the determination of Geogrid size, quantity, and
lengths. Internal stability analyses are: the Geogrid layers layout, tension failure and the
Pullout failure. There is two possible limiting or failure conditions for reinforced walls:
rupture and pullout of the Geogrid. The corresponding properties are the tensile strength
and its pullout resistance.
Potential
failure
plane
Active zone
T = Total tensile
force to be resisted
by Geogrid
Resisting zone
Figure 2. Adherence capacity of geogrid reinforcement
Calculations (FHWA-NHI-00-043):
i. Consider Geogrid layer vertical spacing (Vs) = 0.47m
ii. Tension calculation at each Geogrid reinforcement level T(Max) = σH x Vi
iii. Allowable strength (Tall) = [Ultimate strength (Tult) x RC / FS uncertain x
FSID x Creep reduction factor]
Where, FS uncertainties = 1.5, FSID = 1.1,
RC = the percent coverage ratio (100 % coverage is assumed for this case) So
RC = 1, Creep reduction factor = 3.10
iv. Pullout calculation at each layer Tmax ≤ (1/ FSPO) (tan φ
Ci) (γr) (di) (Le) (C) (Rc) (α) Where, FSPO = factor of
safety against pullout = 1.5,

26. Ci = interaction coefficient determined from pullout testing for a particular
reinforcement type. Ci = 0.8,
γr = unit weight of reinforced soil mass, di =
depth below top of wall. Le = length of
reinforcement in resistance zone. C = 2 for
Geogrids.
Rc =% coverage of Geogrid (may vary from 100% to 70%). Rc assumed to be
100% for this example,
α= scale effect correction factor (α = 1.0)
v. Length of Geogrid in active zone LA = (H – di) x tan (45o - φ / 2).
Table 2 Output for 7.04 m wall for type and length of geogrid at each
layer.
Layer
No
Depth (di)
from Tmax
Type of
ACE T(all) L(required)
L
(provided)
Top (m) (kN/m) Geogrid (kN/m) LA + Le (m) (m)
1 0.47 6.64 GG40-I 7.82 4.495 5.0
2 0.94 5.67 GG30-II 5.86 4.245 5.0
3 1.41 6.86 GG40-I 7.82 3.995 5.0
4 1.88 8.10 GG60-I 11.73 3.745 5.0
5 2.35 9.34 GG60-I 11.73 3.495 5.0
6 2.82 10.58 GG60-I 11.73 3.245 5.0
7 3.29 11.81 GG80-I 15.64 2.995 5.0
8 3.76 12.97 GG80-I 15.64 2.745 5.0
9 4.33 14.29 GG80-I 15.64 2.495 5.0
10 4.70 15.52 GG80-I 15.64 2.245 5.0
11 5.17 16.76 GG100-I 19.55 1.995 5.0
12 5.64 18.00 GG100-I 19.55 1.795 5.0
13 6.10 19.23 GG100-I 19.55 1.495 5.0
14 6.58 30.27 GG150-I 39.10 1.245 5.0
It is observed that total length of Geogrid required at each layer is less than length
required from external stability analysis. So length of Geogrid provided is equal to 5 m
at each layer.

27. 27
2.3 Wedge Stability
It is essential to ensure safety of geogrid reinforced earth wall against failure over potential
sliding plane. Stability of any wedge is maintained when frictional forces acting on the
potential failure plane in connection with the tensile resistance or bond of the group of
reinforcing elements embedded in the fill, bed and the plane are able to resist the applied
force tending to cause the movement (Figure 3).
P = Frictional and
cohesive force
N = Normal reaction q
= Surcharge weight
T = Total tensile force to
be resisted by Geogrid
Figure 3. Forces acting on Potential failure planes
Calculations (BS8006: 1995):
i) Resolving the forces vertically. W T = N Sin β + P Cos β
ii) Resolving the forces horizontally. T + P Sin β - N Cos β – F3 =0
iii) Residual length (effective length) Lr = L – (H - di) Tan β
iv) Calculation of resisting force at each layer
a)Rf = Tall x Lr,
b)Rf = μ x Lr (γr x di + q) [Ref.B.S 8005: 1995 (Cl. 6.6.4.2.5)]
The lesser value for each layer should be used in the summation.
Based on the procedure listed under illustrative computation, a computer programme is
developed to calculate Rf for all reinforcement layers & min. value of each layer is consider
for summation. The output is obtained for 7.0 m height of wall.

28. 28
Table 3. Output for wedge stability analysis
Sr. No.
Depth of layer
(di) (M)
Resisting
Force (kN)
1 0.47 11.76
2 0.94 10.27
3 1.41 15.64
4 1.88 26.43
5 2.35 29.37
6 2.82 32.30
7 3.29 46.92
8 3.76 50.90
9 4.23 54.74
10 4.70 58.72
11 5.17 78.20
12 5.64 83.18
13 6.10 88.07
14 6.58 185.92
∑ Rf =
760.66 kN
FOS =
∑ Rr = 760.66 = 2.84 > 1.5 (Hence O.K)
T 267.63
FOS against wedge stability for height 7m is greater than 1.5; hence structure is safe.

29. 29
13.0 Conclusion
Land only covers 29.22 percent of the Earth surface which water covers the other
70.78 percent of the Earth's surface. The land is still depleting because of the rising of sea
level due to global warming. Therefore, we should make good use of the existing land. By
fully utilizing the land, we will be able to help in solving the land scarcity problem.
From the vast development in the infrastructure field, the land under the flyover has
now draws the attention of the developers. It is a waste of land if the space under the flyover
is left empty. However, there is a reason why this is happening. This is because from the
safety aspect, ‘nothing’ should be built under the flyover.
Things change with the situation, adaptability, that’s the basic rule of life. In a fully
developed city where there’s no more land to develop, the land under the flyover is as
precious as diamond in the developers’ eyes. Thus, the developers urge the local authorities
to re-consider of allowing development under the flyover. But there’re still specifications and
requirements that need to be follow by the developers and the Engineering department from
the local authority should decide whether the development is safe to be build from all aspect.
In conclusion, the final decision whether the development should be permitted or not
lies on the shoulder of the engineer from local authorities. The development under the flyover
should be seen as fulfilling one of the urban planning strategies in minimizing the wastage of
land. There are a lot of potential of land use under the flyover however to avoid any tragedy
from happening, safety awareness is very essential in the development.

30. 30
14.0 References
I. MDC Legal Advisers, National Land Code Act 56/196, MDC Publishers Printer Sdn.
Bhd., 2001
II. Offside Futsal Park opens under Thomson Flyover-Singapore
http://www.futsalplanet.com/news/news-01.asp?id=15963
III. Australian Freeways and Roads
http://www.skyscrapercity.com/showthread.php?t=434396&page=19
IV. Under the Flyover | URBZ
http://urbz.net/workshops/mashup/mumbai/under-the-flyover/
V. Space under Flyovers, Praja
http://praja.in/en/blog/varsh/2010/03/26/spaces-under-flyovers
VI. Cebu Daily News
http://cdn.ph/news_details.php?id=12602
VII. A community space under a traffic flyover is the latest hip hangout
http://uk.phaidon.com/edit/art/events/2011/july/19/a-community-space-under-a-
traffic-flyover-is-the-latest-hip-hangout/
VIII. The writers would like to thank Mr. Karamarakar, Mr. Konage of M/s Dar
Consultant Pune for providing us the detailed information of the flyover at
agriculture college road, Pune, India. The writers also would like to thank faculty
of Civil Engineering Department of COE, Pune and AISSMS College of
Engineering, Pune.
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