Highway

UNIT – III

Chapter - 10

HIGHWAY AND RAILWAY AN INTRODUCTION

HIGHWAY

 

1. SCOPE OF HIGHWAY ENGINEERING

The road pavements are generally constructed on low embankments, above the general ground level or the adjoining land. Embankment is a raised bank of earth or other materials constructed above the natural ground. The pavement is to avoid the difficult drainage and maintenance problems. The term road or roadway thus constructed is therefore termed 'highway'. The science and technology dealing with roads is generally called 'Highway Engineering' or 'Highway Technology'. .

An overview of transportation engineering was already given in Chapter 1(F). Highway Engineering deals with various phases like traffic and transportation studies and analysis, planning of road net-work, alignment, design of road geometries, materials, pavement design, construction and maintenance, highway traffic operation, safety, regulation and administration.

Appropriate investigations as well as economic and financial analysis are essential before planning a road project. Environmental and social impact assessment studies and roadway aesthetics are also needed. Specific problems such as alignment, design and construction of roads in high altitudes and difficult terrains also form a part of highway engineering studies.

 

2. OBJECTIVES OF TRANSPORTATION SYSTEM

The social and economic developments of any region or country depend very much on the efficiency of the transportation system. Hence, a well-planned development of transportation system deserves high priority. Road transport system could serve independently or as feeder service to other modes of transport. Considering the importance of energy conservation, efficiency and cost, an optimum mix of different modes of transportation has to be planned and developed. It is also desirable to have appropriate coordination between different modes of transport.

 

3. OBJECTIVES OF HIGHWAY PLANNING

Planning is considered as a pre-requisite before attempting any development programme in the present era. This is particularly true for any engineering project, as planning is the basic requirement for any new project or an expansion programme. Thus, there is a need for development of the road network and the links.

Highway planning is of great importance when there are limited funds and total requirement is much higher. It is important to utilize the available funds in the best possible manner by resorting to best planning principles.

The objectives of highway planning are given below:

a) To plan overall road network for efficient and safe traffic operation, at minimum cost.

b) To arrive at the road systems and the lengths of different categories of roads for maximum utility.

c) To divide the overall plan into phases and decide priorities.

d) To prioritize development of each road link based on utility as the main criterion.

e) To plan for future requirements and improvements of roads.

f) To work out suitable financing system.

 

4.  PHASES OF HIGHWAY PLANNING

Highway planning includes the following phases:

a) Assessment of road length requirement for an area (it may be a district, state or the whole country).

b) Preparation of master plan showing the phasing of plan in five-year plans or annual plans.

In order to plan the road system in the selected region, state or country, studies and surveys are to be carried out to collect data. The data collected are to be processed and analyzed to arrive at the best possible road network and to arrive at the optimum length of the road system.

 

5. CLASSIFICATION OF ROADS

The classification of roads based on various aspects is already explained in Chapter 1(F) - Section 3. In the above section, roads in India are classified into five categories as NH, SH, MDR, ODR and VR as per Nagpur Road Plan. The road classification system was modified in the third 20-year road development plan as given below.

Modified Road Classification as per third 20-year Road Development Plan, 1981 - 2001

The roads in the country are now classified into three classes for the purpose of transport planning, functional identification, earmarking administrative jurisdictions and assigning priorities on a road network:

i) Primary system

ii) Secondary system and

iii) Tertiary system or rural roads

Primary system consists of two categories of highways:

a) Expressways and

b) National Highways(NH)

Expressways are a separate class of highways with Superior facilities and design standards and are meant as through routes having very high volume of traffic. The expressways are to be provided with divided carriageways, controlled access, grade separations at cross roads and fencing. These highways should permit only fast-moving vehicles.

Expressways may be owned by the Central Government or a State Government. It depends on whether the route is a National Highway or State Highway. The National Highways form the other main category of primary system in the country.

The Secondary system consists of two categories of roads:

a) State Highways (SH) and

b) Major District Roads (MDR)

The Tertiary system comprising rural roads consists of two categories of roads:

a) Other District Road (ODR)

b) Village Roads (VR)

The definitions of NH, SH, MDR, ODR and VR are the same as given under classification of roads by Nagpur Road Plan.

Classification of Urban Roads

The road systems within urban areas are classified as urban roads. They are to be taken care by the respective urban authorities. The lengths of urban roads are not included in the targets of the third Twenty Year Road Development Plan 1981-2001.The urban roads are classified as: (i) Arterial roads, (ii) Sub-arterial roads, (iii) Collector streets, and (iv) Local streets.

Arterials and sub-arterials are urban roads primarily for through traffic on a continuous route. The sub-arterials have a lower level of traffic mobility than the arterials. Collector streets provide access to arterial roads. They collect and distribute traffic from and to local streets which provide access to adjacent property.