Review of road network

BAYARO UNIVERSITY KANO
DEPARTMENT OF CIVIL ENGINEERING
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REVIEW OF ROAD NETWORKREVIEW OF ROAD NETWORK
Presented by : submitted to:Presented by : submitted to:
Nasiru Adamu Abdul’aziz, Eng.Nasiru Adamu Abdul’aziz, Eng. Dr. Hashim M Alhassan MNSE
October, 2016

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1.0 INTRODUCTION OF ROAD NETWORK1.0 INTRODUCTION OF ROAD NETWORK
2.1 Concept of Road Network2.1 Concept of Road Network
2.2 Road Network Characteristics2.2 Road Network Characteristics
2.3 Hierarchy of Road Network2.3 Hierarchy of Road Network
2.4 Classification of Road Network2.4 Classification of Road Network
2.5 Design of Road Network2.5 Design of Road Network
2.6 Road Network Formation & Construction2.6 Road Network Formation & Construction
2.7 Road Network Failure & Maintenance2.7 Road Network Failure & Maintenance
3.0 CONCLUSION3.0 CONCLUSION
Presentation OverviewPresentation Overview

 Road networks can be defined as series of nodes and
links which represents spatial locations and connections
exhibiting geometric variations and topological variations.
 As part of research many researchers have done
contribution by making base of these two factors and then
introducing higher attributes such as spacing, shape,
orientation and geometric patterns.
 In the past i.e. early 1960s network characteristics and
structure were measured by geographers and
transportation researchers (Garrison 1960, Marble 1962
and Kansy 1963) by using graph theoretic network
analysis constrained by limited data.
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1.0 Introduction of Road Network1.0 Introduction of Road Network

 Attempts have been made in the past for implementing the
concepts of fractal dimension in road network by
Hausdrauff 1969 and Richardson 1971.
 With the introduction of various travel demands models
researchers (Newel 1980 and Vaughan1987) have
explored about how the traffic flows and travel pattern are
affected by various geometric network structures.
 In the same year El-Geneidy and Levinson 2006 have
defined the Access to Destinations study using detailed
data on land use, travel behavior, and population
demographics to evaluate accessibility in a particular
situation.
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 These studies have focus more on the fractal nature of
a specific element of urban transportation network
which have given formulations and empirical results
revealing the fractal nature of urban road network, they
are not systematic in the sense that cities were not
selected according to population, size or extent.
 In view of this we can say that the results are not
complete and less useful in urban networks and it is
evident that the fractal dimension has been an integral
part of fractal geometry in particular to the distribution of
road network.
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 The Road Network is one of the largest and most important
infrastructure in most of the countries. It is at the core of
national transport system. Its connect a major towns and
cities, and help millions of people movement from one
place to another.
 A motorways and major roads are the most heavily used
part of the national road network.
 A road network provide business with the means to get its
products and services to their customers, give access to
labour markets and suppliers and encourage trade and new
investment. Road network are essential to the growth,
wellbeing and balance of the nation’s economy.
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 A Concept of Operations is a document that describes in
easily understood language how a system works from
the viewpoint of those who operate it.
 How to influence a demand by ensuring that a road
users have the information they need, in the format they
prefer, at the time when they need it; to allow them to
plan and manage their journey with a high degree of
confidence of knowing when they will arrive.
 How to continuously improve availability through
reducing the impact of incidents, smarter planning of
road works, and by educating and informing users.
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 The Concept of Operations is a set of guiding principles
that will drive the enhancement of our operational
capability as part of our transformation journey both within
the current Delivery Plan period and beyond.
 The stability of road networks has become an increasingly
important issue in recent times, since the value of time
has increased considerably and unexpected delay can
results in substantial loss to road users.
 Road network reliability has now become an important
performance measure for evaluating road networks,
especially when considering changes in OD traffic
demand and link flow capacity over time.
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 A network can be defined as a set of linear features
through which resources flow.
 Nodes (the end points of lines) are used as origins and
destinations, and links (lines) traverse from one node to
the other.
 Nodes can have properties but in network analysis we
are usually more concerned with the characteristics of
the links (Laurini and Thompson, 1992). These include:
• Length
• Direction
• Connectivity (lines must connect at least two points), and
• Pattern

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KEY CHARACTERISTICS OF THE NETWORK DESIGN METHOD
 Designing successful transportation networks requires more than
the application of the functional classification. In order to assist
stake holders in the design process, a step-by-step design
process is setup.
 It is not a blueprint that tells stakeholders exactly what to do,
merely a frame work within which they make decisions.
 The stakeholders get to make the designs, but the method brings
structure to the design process, by indicating which decisions
need to be made at what point in the process.
 It is based on a number of important characteristics, which are
listed in random order below.
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First Structure, then Elements
 First, a perspective on the complete structure of the network must be
developed, such as which cities must be connected by the network, which
scale levels are distinguished, etc.
 Only then can a decision be made about the elements (road sections,
junctions, and routes/alignment). In practice, problems are usually solved at
the element level: bottle neck by bottle neck.
First the Higher Scale Level, then the Lower Scale Level
 Networks for every scale level are designed independently, following a top-
down approach: from the higher to the lower scale level, with a feedback
loop bottom-up.
 Each network is designed to meet its functional requirements optimally, to
achieve coherence between networks of different scale levels, access points
of higher scale level are automatically included in the lower scale level.
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First the Collective Networks, then the Individual Networks
 Access to collective transport systems is much more cumbersome
than access to individual transport, and therefore the situation of the
access points of the collective system (public transport stops) requires
more careful consideration than the situation of access points of the
individual networks (e.g., highway and freeway entry points).
First Ideal, then Existing
 First, an ideal network is designed, ignoring the existing network.
Subsequently, this ideal structure is confronted with the existing
situation. The actions that need to be taken to change the existing
situation into the ideal situation can then be prioritized. This way,
improvements in the existing networks will be coherent; the ideal
structure serves as along-term perspective.
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 You can perform network analysis using the hierarchy of the
network. Typically there are three to five levels.
1. Primary roads (freeways, express and limited-access highways)
2. Secondary roads (major and sub arterial roads)
3. Local roads (collectors and local streets)
 Performing network analysis using a hierarchy makes use of a
heuristic that reduces the computation time by limiting the search
mostly to the higher levels of the hierarchy.
 For instance, with a three-level hierarchy, only the local roads are
considered in the immediate vicinity of the start and end of the
route, and only the secondary roads are considered in the
greater vicinity of the start and end of the route.
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 Because most of the route only considers roads in the higher
levels of the hierarchy, this may result in a solution with a
slightly higher cost than if you were to solve the same
problem without using the hierarchy.
 It typically takes less time to compute a solution using a
hierarchy. This time difference is especially pronounced
when the network is large, your primary and secondary roads
are thoroughly interconnected, and your stops are not
clustered together on local roads.
 Driving directions for primary and secondary roads are often
easier to follow, since street signs are more visible and there
are fewer intersections.

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 The results from a network analysis using a hierarchy
can emulate the preference of drivers on the road. For
example, truck drivers typically prefer routes on primary
roads, since traveling on local roads increases the
likelihood of difficult turning maneuvers and stopping,
which consequently lowers their fuel efficiency and
increases their emissions.
 Note that while a road in a higher level of hierarchy is
more likely to be in the result of a hierarchical analysis,
the road is not necessarily more favored by the solver
than roads in the lower levels of the hierarchy.

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 Even when you have the option of performing a
hierarchical analysis, you can choose to ignore
hierarchies.
 You should base your decision on your data and your
particular network problem. If you aren't sure, run the
analysis with and without the hierarchy, compare the
results, and decide which results are the best fit for you.
Using hierarchy by default
 As long as the network dataset has a hierarchy attribute,
you can set any network analysis layer you create to use
the hierarchy by default.

 To change this setting, use the Catalog window in ArcMap
to open the Network Dataset Properties dialog box. Click
the Attributes tab, right-click the hierarchy network attribute,
and click Use By Default.
 You can also choose to enable hierarchies in ArcMap for
each network analysis layer that you add by following these
steps: open the Layer Properties dialog box for your
network analysis layer, click the Analysis Settings tab, and
click Use Hierarchy.
 Alternatively, you can perform a normal analysis by un
checking Use Hierarchy
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The roads can be classified in several ways. Various
classifications are give as follows:
 Classification based on materials of construction.
1. Natural earth roads. 2. Stabilized soil roads
3. Gravel roads. 4. Moorum roads.
5. Water-Bound-Macadam roads. 6. Bituminous roads.
7. Cement concrete roads. 8. Block paving.
 According to the volume of traffic they handle.
1. Light traffic roads 2. Medium traffic roads.
3. Heavy traffic roads.
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2.4 Other Classification of Road Network2.4 Other Classification of Road Network

 According to the type to traffic they handle.
1. Foot paths or Pedestrian ways. 2. Cycle tracks
3. Moto carriage ways. 4. Express ways.
 According to the number of lanes in the roads.
1. Single lane roads. 2. Double lane roads.
3. Three lane roads. 4. Multi-lane roads.
 According to the direction of movement of traffic
1. Both way roads. On such same lane is used by the traffic moving in
both the directions.
2. Dual carriage ways or roads. In this system separate lanes are
provided for the traffic, moving in opposite directions. These lanes
are further separated with the help of median strips or grass verges
or central reserve spaces.
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 According to the area they traverse.
1. Low cost roads.
I. Natural soil roads. II. Stabilized soils roads.
III. Gravels roads. IV. W.B.M roads.
2. Medium type road
I. Bituminous surface treated roads. II. Bituminous Macadam roads.
III. Premix bitumen carpet roads. IV. Cement bound Macadams roads.
3. High type roads.
I. Bituminous concrete roads II. Sheet asphalts roads.
III. Cement concrete roads. IV. Block paving or pavements.
 According to rigidity of the roads.
1. Flexible pavements. 2. Rigid pavements.
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 Design criteria consist of a detailed list of considerations to be
used in negotiating a set of road standards.
 These include resource management objectives,
environmental constraints, safety, physical environmental
factors (such as topography, climate, and soils), traffic
requirements, and traffic service levels.
 Additional objectives may also be defined concerning specific
needs or problems identified in the planning stage:
 Resource management objectives: Why is the road being
built; what is the purpose of the road?
 Physical and environmental factors: What are the
topographic, climatic, soil and vegetation characteristics of the
area?
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 Environmental constraints: Are there environmental constraints;
are there social-political constraints? Examples are erosiveness of
soils, difficult geologic conditions, high rainfall intensities. And also
land ownership boundaries, and public opinion about a given
project.
 Traffic requirements: Average daily traffic (ADT) should be
estimated for different user groups. For example, a road can have
mixed traffic--log or cattle trucks and community traffic. An estimate
of traffic requirements in relation to use as well as changes over
time should be evaluated.
 Traffic service level: This defines the type of traffic that will make
use of the road network and its characteristics. Each level describes
the traffic characteristics which are significant in the selection of
design criteria and describe the operating conditions for the road.
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 Vehicle characteristics: The resource management objectives,
together with traffic requirements and traffic service level criteria
selected above will define the types of vehicles that are to use
the proposed road. Specific vehicle characteristics need to be
defined since they will determine the "design standards" to be
adopted when proceeding to the road design phase.
 Safety: Traffic safety is an important requirement especially
where multiple user types will be utilizing the same road. Safety
requirements such as stopping distance, sight distance, and
allowable design speed can determine the selected road
standards in combination with the other design criteria.
 Economics: The various road alternatives would undergo
rigorous economic evaluations.
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 After the finalization of the road alignment, detailed survey work is
carried out, longitudinal and cross-section are drawn, formation level
is marked on the longitudinal section and cross-section.
 Pegs are driven on the centre line at about 30 m interval and suitable
profiles are erected where ever change in section occurs. Dig belling
is also done marking upper formation width, and the base width.
 Spaces for barrow pits are also marked in case of filling and spoil
banks in case of cutting. After having completed all these preliminary
work. Earth work is stated.
 Clearing the site
 Earth work
 Cutting
 Embankments
 Soil compaction
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2.6 Road Network Formation & Construction2.6 Road Network Formation & Construction

 To be successful road engineer, it is very essential to have a sound
knowledge of design and construction aspects of the road and also
various defects that are likely to occur and methods of their rectification.
 Likely causes of failures should be investigated and designs should be
done as per local conditions of the construction site.
General Causes of Road Failures
I. Faulty materials of construction.
II. Faulty construction and improper quality control during construction.
III. Inadequate surface and sub-surface drainage of the road structure.
IV. Increase in value of wheel load.
V. Increase in traffic volume.
VI. Settlement of Foundation of embankment of fill material.
VII. Environmental factors like rain fall, soil erosion, high water table etc.
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 Road if constructed without any scientific basis, will require
an elaborate maintenance.
 Scientifically a road network required maintenance, But to
the laser degree if constructed by adopting all scientific
fundamentals.
 A pavement may be in use or not maintenance for up keep
is most.
Classification of maintenance
 1. Routine maintenance or repairs
 2. Periodic maintenance
 3. Special maintenance

 Improved road network facilities provide various benefits to the
community. With improved highway, transport net work improves,
and travel time, and accidents are minimized.
 Cost of land adjoining new improvement highway increases. All the
benefits which can be derived from highway improvement, should be
analyzed and summed up to determined its economic viability.
 Any proposal for new road or improvement should be weighed by
comparing benefits expected to be derived and cost of proposed
new work.
 Hence before finalizing any proposal for improvement or new work,
economic analysis is a prerequisite and it is only the economic
aspect which will provide maximum justification for committing public
money investment.
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3.0 Conclusion3.0 Conclusion

Segebaden von, G., (1964). “Studies of cross-country
transport distances and road net extension. Studia
Forestalia Suedica, No. 18”.
Sidle, R. C. (1980). “Slope stability on forest land. USDA
Forest Service Research Paper PNW209”.
Transportation Research Board, (1978). “Geometric
design standards for low-volume roads, Compendium 1.
National Academy of Sciences and U.S. Agency for
International Development, Washington, D.C”.
Gavin Macpherson, “Highway and Transportation
Engineering and Planning”
Hutchinson B.G, “Introduction to Urban System Planning”
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ReferencesReferences

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