Introduction to Highway Eng | Highway Engineering

 

Chapter: 1                   INTRODUCTION

1.1         Different modes of transportation

·            Road ways (car, bus taxi, bike etc.)

·            Rail ways (train, bullet container etc.)

·            Air ways (helicopter, plane, aircrafts etc.)

·            Water ways (ship, boat etc.)

·            Rope ways (zipline, cable car etc.)

·            Space ways (rocket, Satellite etc.)

·            Tunnel ways

 1.2 Benefits of Road

·        Easy to travel from one place to another place

·        Saving of time

·        Development of city

·        Easy to Import and Export

·        Wide geographic coverage: Roads can be constructed to penetrate the interior of any region and to connect remote villages. Hence, it has wide geographical coverage.

·        Door to door service: Roads are only modes of transportation, which offers door-to-door service unlike railways and airways.

·        Low capital  investment: Roads can be constructed with comparatively lower initial cost than railways and airways. The cost of the roads varies with the specifications, but even the best road is cheaper than a railway line. Stage construction is feasible for roads not for railway.

·        High Employment potential: Road transportation has employment potential during and after its constructions.

·        Safety:  Road  accidents is less dangerous than railways or air accidents. Hence it is safer.

1.3         Importance of road for Nepal

Nepal is land lock country so, there is only one option of choice for us to travel one place to another place used road ways. In Nepal 90% of passenger depends upon road ways for there daily activities for different part of country. If is poor road connectivity it is difficult to transpor  goods (heavy materials) from one place to another place.

1.4  Classification of Road according to NRS

(A)      Administrative classification

                1. National Highways

                2. Feeder Roads

                3. District Roads and

                4. Urban Roads                                                                                                      Explain:

National highway: National Highways are main roads connecting East to West and North to South of the Nation. These highway service directly the grade portion of national provide constantly high level of service connect the community of different region.

Feeder road:  Feeder roads are important roads of localized nature. These serve the community's wide interest and connect District Headquarters, Major economic centre, Tourism centre to National Highways or other feeder roads.

District road: District road are the main road with in the district serving  area of production, market and connecting with each other or Nation highway or feeder roads.

 Urban road: Urban road are the main road connecting with in the city or municipalities and it also connect of district type of roads.

(B)        Technical classification

1.     First class

2.     Second class

3.     Third class

4.     Fourth class

Explain:

First class:  First class roads are the higher strandard of road which divided the carriage way and access traffic of more than 20 thousand passenger card unit (PCU). The design speed of this road on plain terrain is 1020km/hr.

Second class:  Second class road is the those  type of road in which annual daily traffic (ADT) is five thousand two hundred PCU. The design speed of second class road in plain terrain is 100km/hr.

Third class:  Class III roads are those  ADT is 2000-5000 PCU. Design speed adopted for design of this class of roads in plain terrain is 80 km/hr.

 Fourth class: c lass IV roads are those ADT is less than 2000 PCU. The design speed of second class road in plain terrain is 100km/hr.

1.5  Role of roads in rural development

(a) creating opportunities for agriculture and economic activities

(b) Provides better access to health, social, health and other community services.

(c)Upgrading social status 

 (d) Easy to installation electricity, telephone, internet and other facilities.

 

1.6  History of development of road

(a)        Early development 

                    i.            The oldest mode of transportation own on foot track.

                 ii.            Animals were used to transport mean and material.

                iii.            Animal drawn vehicles were develop and become very popular at that time

               iv.            The necessity of providing hard surface four wheeled  vehicle which was supposed to develop Mesopotamia. 

(b)       Roman road

                   i.            In roman period many roads were build on stone blocks of considerable thickness.

                 ii.            These roads were builded   straight and provided stone gradient.

               iii.            The soft soil was excavated and remove fill the high strata was reached.

               iv.            The total thickness of construction road was 0.75m to 1.25 m at some places where the magnitude load of wheel load was very low.

                 v.            Some of roman road still exist after 200 years.

(c)        Tresaguet  development

 

                   i.            Tresaguet  development in improved method of construction of road which was most cheaper than roman road.

                 ii.            The thickness of construction was 30cm and consideration was made sub-grade and drainage is constructed.

              iii.            The sub-grade was prepared stone layer and compacted it.

              iv.            The top most layer or wearing was made to thickness about 5cm and gradual compaction method is used from edge to center of the road.

                 v.            The shoulders were also provided cross slope to drain surface water to side drain.

(d)       Telford construction

 

Telford believed in using heavy foundation of stone above soil sub-grade. He provides cross-slope for top surface of pavement of varying thickness of foundation stone. The main features of Telford construction are as follow:

       i.            A level sub-grade was prepared to design width of about 9 m.

     ii.            The stone of less thickness were placed toward the edge and stone of more thickness were placed at the center.

    iii.            The inter-section between foundation stones were properly graded and well compacted.

(e)        Modern road construction

All of the modern roads are improvements over the macadam construction. Bituminous binders were made use of instead of stone or mud binders. Flexible pavements with bituminous layers, rigid pavements and WBM road are the example of modern road construction.

 1.7 Rural and Urban road;Advantages and Disadvantages
      Advantages of Rural road:

1)   It help to participatory, planning, construction and maintenance of roads.

2)   Employment generation for local people.

3)   Rural are low cost, So, Rural roads construction and maintenance cost is low.

4)   Community empowerment along with development of roads.

5)   Rural roads are lifetimes of  rural people.

6)   Planned development of road network according to the requirement of community.

7)   Rural road helps for a system development for local management of road operation by local community.

Disadvantages of Rural Road:

1)   There are maximum chances of erosion and wearing of rural roads.

2)   Rural road maintenance become irrigation due to large number of maintenance work with in year.

3)   Passenger fills less comfort during traveling.

       4) The speed of vehicle is less. so, it takes longer time for transportation 

  Advantages of Urban  road:

1)     Urban roads can use in all-weather condition.

2)     The travel spewed on urban road is higher as compared to rural road.

3)     Urban roads have less maintenance in the duration of year only few minor maintenance can improve original condition of roads.

4)     Maintenance cost is low.

5)     It help to accelerate the business activities of urban people.

  Disadvantages of Urban  road:

1)     Initial construction cost is very high as compared to rural road.

2)     Traffic congestion is high so it made people discomfort for movement.

3)     Due to high speed of travel there is higher chances of fatal accidents.

4)     Maintenance cost is very high.

 1.8 Types of Feeder Roads

1)     Earthen Road

2)    Gravel Road

3)      Bituminous Road

4)     WBM Road

5)  Concrete Road (RCC and PCC)

 1.9 Urban Road patterns

A. Rectangular or Block pattern:

   In this pattern whole area of road divided into rectangular or block pattern. The main road is passing    through the center   of city and   should be sufficiently wide and  connected to  other branch of  comparatively narrow road.  The main road is  provided a direct approach to the outside city.

                                                              

B.     Radial or Star and block Pattern:

In this pattern, the entire area is divided into a radial   network of   roads   radiating from the business centre outwardly.  Road planed in such way that all   the economic center and measure built area should be covered.  

C.     Radial or Star and Circle  Pattern:

         In this type of road are inter-connected the central business area and also connected the different branch of road with in the circular area of city. In this  area circular road is finally meet at the starting point of the road. In Nepal this type of road is mainly constructed for large city like kathmandu valley.

 

D. Hexagonal pattern

In this pattern, the entire area is provided  with a network of roads formatting hexagonal figures. At each  corner of  the  hexagon, three roads  meet.  The built- up   area  boundary  by the sides  of  the  hexagons  is  further   divided in suitable sizes.