BAYARO UNIVERSITY KANODEPARTMENT OF CIVIL ENGINEERING

1

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

s

2

1.0 INTRODUCTION OF ROAD NETWORK1.0 INTRODUCTION OF ROAD NETWORK

2.1 Concept of Road Network2.1 Concept of Road Network2.2 Road Network Characteristics2.2 Road Network Characteristics2.3 Hierarchy of Road Network 2.3 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.

3

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.

4

1.0 Introduction of Road Network1.0 Introduction of Road Network

.

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.

5

1.0 Introduction of Road Network1.0 Introduction of Road Network

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.

6

2.1 Concept of Road Network2.1 Concept of Road Network

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.

7

2.1 Concept of Road Network2.1 Concept of Road Network

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.

8

2.1 Concept of Road Network 2.1 Concept of Road Network

9

2.2 Road Network Characteristics 2.2 Road Network Characteristics 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

2.2 Road Network 2.2 Road Network Characteristics Characteristics

10

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.

11

2.2 Road Network Characteristics 2.2 Road Network Characteristics

12

2.2 Road Network Characteristics 2.2 Road Network Characteristics

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.

13

2.2 Road Network Characteristics 2.2 Road Network Characteristics

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.

14

2.2 Road Network Characteristics 2.2 Road Network Characteristics

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.

15

2.3 Hierarchy of Road Network2.3 Hierarchy of Road Network

16

2.3 Hierarchy of Road Network2.3 Hierarchy of Road Network

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.

17

2.3 Hierarchy of Road Network2.3 Hierarchy of Road Network 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.

18

2.3 Hierarchy of Road Network2.3 Hierarchy of Road Network 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

19

2.3 Hierarchy of Road Network2.3 Hierarchy of Road Network

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 roads3. 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.

20

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 tracks3. 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 traffic1. 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.

 

21

2.4 Other Classification of Road Network2.4 Other Classification of Road Network

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 roadI. 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.

22

2.4 Other Classification of Road Network2.4 Other Classification of Road Network

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?

23

2.5 Design of Road Network2.5 Design of Road Network

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.

24

2.5 Design of Road Network2.5 Design of Road Network

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.

25

2.5 Design of Road Network2.5 Design of Road Network

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

26

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.

27

2.7 Road Network Failure & Maintenance2.7 Road Network Failure & Maintenance

28

2.7 Road Network Failure & Maintenance2.7 Road Network Failure & Maintenance 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.

29

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”

30

ReferencesReferences

31

Thank You !