25-08-2017, 09:32 PM
RURAL ROAD DEVELOPMENT
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INTRODUCTION :
Rural roads are the tertiary road system in total road network which provides accessibility for the rural habitations to market and other facility centres. In India, during the last five decades, rural roads are being planned and programmed in the context of overall rural development, and tried to provide allweather connectivity with some level of achievement. The long term road development plans for the country provided policy guidelines and priorities for rural roads, while the funds for rural roads were allocated in the Five Year Plans. Recently, during the last five years Government of India has undertaken a dedicated programme known as ‘Pradhan Mantra Gram Sadak Yojana (PMGSY)’ to provide rural connectivity to all habitations under the Ministry of Rural Development. More recently, Bharat Nirman, a time bound business plan adopted to provided rural infrastructure during 2005-09, rural roads have been taken as one of the components and blended with PMGSY programme. It targeted to provide connectivity to all habitations having population of 1000 and above (500 and above in hilly, desert and tribal areas) by 2009 and also aimed to upgrade the existing rural roads for overall network development, which is a more objective approach.
To achieve the targets of Bharat Nirman, 1,46,185 km length of rural roads is proposed to be constructed to benefit 66,802 unconnected eligible habitations in the country. It is also proposed to upgrade nearly 1.94 lakh km length of the existing rural roads which are identified as the through routes of the core network. The total investment on rural connectivity under Bharat Nirman has been estimated at Rs. 48,000 crore during 2005-2009. Since 11th Five Year Plan (2007-2011) goes beyond the targeted period of Bharat Nirman, assessment of physical targets and upgradation requirements, have been estimated based on the experiences of PMGSY.
NEEDS OF RURAL ROAD:-
In the year 2000, around 40 per cent of the 825,000 villages in India lacked all-weather access roads. This constrained economic activities and access to essential services. Nearly 74 per cent of India’s rural population, constituting the majority of India’s poor, were not fully integrated into the national economy. The rural roads sector, which is a State subject, also lacked adequate planning and management due to poor coordination between multiple funding streams and agencies. Investing in rural roads was given low priority and viewed in isolation from the need for State and National Highways.
SURVEYING, PLANING AND DESIGN OF RURAL ROAD DEVELOPMENT:-
Before the construction of Rural road the surveying and planning of roads are very important . It is taken before the construction of roads site . To construct a good road,adequate survey, proper planning and design are required.Thealignment of the road has to be decided to ensure proper road geometrics , gradient and effective drainage. A rural road generally consists of basic formation (embankment or cut-formation) and pavement over which the traffic moves. The top 30 cm layer of the formation is compacted more rigorously and is called subgrade. The pavement consists of a number of layers; the type of
layer and their thickness is determined by the nature of ground, strength of soil and alsothe traffic intensity. These layers are sub-base course (compacted granular material like gravel and sand etc.), base – course (watered, rolled and compacted metal and screening, generally called Water Bound Macadam or WBM) and surface course (thin bituminous layer). These layers are constructed to distribute loads and stresses caused by traffic from the upper layers to a wider area of the sub-base course and sub-grade. The roads surface may be unsealed (gravel surface) if the traffic and rainfall is low or sealed (bituminous surface etc.) if traffic and rainfall is high.
• SURVEYING :-
The survey which is conducted for determining quantities and for collecting data for the designing of engineering works such as roads, railways, etc., is known as Engineering Survey. surveying involves the measurement of distances and angles. The distance may be horizontal or vertical in direction. Vertical distances are also calleelevations. Similarly, the angles may be measured in horizontal and vertical plane. Horizontal angles are used to express the directions of land boundaries and other lines.
Before a rural road alignment is finalized in rural road project, the engineering surveys are to be carried out. The surveys may be completed in four stages. The first three stages consider all possible alternate alignments keeping in view the various requirement of rural road alignment.The forth stages is meant for the detailed survey of the selected alignment.
(A) Map Study :-
If the topographic map of the area is available, it is suggested the likely route of the road. In India topographic maps are available from the Survey of India, with 15 or 30 meter contour intervals. The main feature like rivers, hills valleys etc. are also shown on these maps. By carefully study of such maps, it is possible to have an idea of several possible alternate routes so that further details of these may be studied later at the site. The probable alignment can be located on the map from the following details available on the map.
SURVEY OF CROSSING OF POWER LINES:-
The crossing of existing power lines shall be at an angle as close to 90 degrees as possible The crossing of the new line over an existing power line is preferably done in the middle of the span between towers of existing power line where there is maximum sag of the conductor. When the line to be constructed is crossing another important EHV line for which shutdown may be difficult, suspension towers in combination with angle / dead end towers, with extensions as required, may be used. The crossing of the new line below an existing power line shall be done at locations where
adequate ground clearance for the new line and the specified clearance from the existing power line are available. Such crossing shall preferably be in the mid span between towers /structures of the new power line, where there is maximum sag of the conductor, and near one of the towers of the crossing span of the existing line for taking advantage of the higher height of the conductors. These measures reduce the requirement of increasing the height of the existing line for obtaining the requisite clearance.
SURVEY FOR CROSSING OF RAILWAY TRACKS:-
The angle of crossing should preferably be 90 degrees, but an angle of upto 60 degrees may be permitted in special cases. The crossing span shall be restricted to 300 metres or to 80% of the basic span of the towers of the relevant voltage class, whichever is less. Angle towers are to be provided on both sides.
The minimum distance of the towers of the crossing span from the center of the nearest railway track shall be equal to the height of the tower in metres above normal ground level plus 6 metres.
The crossing span over already electrified railway track shall be located at the middle of overhead equipment span supported by two adjacent traction masts / structures. The distance between any of the crossing conductors of the line and the nearest traction mast or structure under the most adverse conditions shall not be less than 6 metres.
ROUTE MARKING SURVEY :-
At the starting point of the commencement of route survey, at all angle / section points, at every 1.25 km. or part thereof, and at the end point of the route survey, concrete pillars 200 x 200 mm square and height 300 mm shall be buried firmly in the ground for easy identification. The concrete pillars shall have ‘RVPN’ marked on them. The top of these pillars shall be 50 mm below ground level and should not normally project above the ground level. A wooden peg of size 50 x 50 mm and length 150 mm is embedded in the center of the concrete pillars when they are casted. Nails of 25 mm length shall be fixed on the top of these pegs to indicate the location of the center of the survey instrument.
Topographical or Ground Gurvey:-
It is performed in order to determine the relative positions of existing natural and constructed features on a tract of land (like ground elevation, bodies of water, roads, buildings etc.). It provides information on the “shape of the land” hills, valleys, ridges and general slope of the ground. The data’s obtained from a topographic surveys are plotted in a map called topographic map and the shape of the ground is shown with lines of equal elevation called contours. Topographical survey shall be carried out for the full length of the road. The extend will cover the existing right of way, if any, or a minimum 60m wide strip across the road corridor (extending 30m from the centre-line on the both sides). All topographical details like existing roads, tracks, drainage structures, buildings, services/utilities (electric, telephone and water lines), existing road furniture, right of way markers and kilometer posts shall be surveyed..
Identification and Prioritization:-
Rural roads improve access in rural areas. They provide access to markets and social services, stimulate the local economy, stimulate an increase in food production, and help to integrate isolated communities into the national economy. Rural roads contribute to rural development. Ideally all communities should have all year round road access. Road improvements however are expensive and it will take quite some time before all . Currently few roads are added every year and it is therefore important that the procedures used to select roads for rehabilitation and construction select the “best roads” first. Rationale road selection and prioritization criteria should be used to select these roads.
Roads to be improved should not just be selected randomly. The top priorities should be determined by a selection process. Roads are constructed for people. Different people have different needs. Different roads therefore will have a different impact. It is essential to assess the future benefits of a road before a decision about upgrading or construction is taken. If substantial benefits are anticipated then the road deserves a priority. If only limited impact is foreseen then the road does not deserve a priority.