Presentation on theme: "ROADS. Roads Introduction Transportation engineering is one of the most important branches of civil engineering. Transportation means conveyance of human."— Presentation transcript:
Introduction Transportation engineering is one of the most important branches of civil engineering. Transportation means conveyance of human beings and material from one place to another. There are four major means of communication Road ways (Communication by land) Railways (Communication by land) Water ways (Communication by water) Air ways (Communication by air )
Road transport is one of the most common modes of transport. Roads in the form of track ways, human pathways etc. were used even from the pre-historic times. Road is a path specially prepared for the movement of transport vehicles. It can also be defined as a structure constructed to facilitate the movement of persons and materials from one place to another.
MODES OF TRANSPORT ROADWAY RAILWAY AIRWAY SEAWAY
ROADWAY Acts as a feeder to all other means of transport All other ways are connected by road ways Fastest mode-airways
Advantages Roads facilitate communication on land essential for economic prosperity and general development of a country in the growth of trade and other economic activities in and outside the villages and towns. as feeder lines help the development of other means of communications. Better law and order can be maintained. Natural resources of an area can be easily tapped and improved.
STRUCTURE OF ROAD
A highway pavement is a structure consisting of superimposed layers of processed materials above the natural soil sub-grade, whose primary function is to distribute the applied vehicle loads to the sub-grade.
Wearing course (surface to road) It is the top surface of the road. It directly receives the wheel load. Sub-grade It is the natural foundation soil upon which the whole pavement rests and to which the vehicle loads are finally transmitted. Base course It is the portion between the wearing course and the sub grade Right of way This is the width of the land to be acquired for road purpose keeping in view of future requirements.
Carriage way The central paved width of road which is used for vehicular traffic is called carriage way Shoulder width It provides lateral stability to the road and additional space for vehicles while overtaking other vehicles. Road way width This is the width of formation at the top. It is equal to the width of carriage-way and width of shoulders on either side. Camber The rise give to the centre of carriage-way with reference to its edge is called camber.
Requirements of a pavement Sufficient thickness to distribute the wheel load stresses to a safe value on the sub-grade soil Structurally strong to withstand all types of stresses imposed upon It Adequate coefficient of friction to prevent skidding of vehicles, Smooth surface to provide comfort to road users even at high speed, Produce least noise from moving vehicles, Dust proof surface so that traffic safety is not impaired by reducing visibility, Impervious surface, so that sub-grade soil is well protected Long design life with low maintenance cost.
Classification of roads Based on type of carriageway Based on pavement surfacing Based on location and function Based on structural performance Based on the traffic volume in that road Based load transported through that road
Based on type of carriageway Paved roads Unpaved roads Paved roads Unpaved roads
Based on pavement surfacing Surfaced roads-A road with a hard smooth surface of bitumen or tarroadhardsmoothsurfacebitumentar Unsurfaced roads -A road without a hard smooth surface of bitumen or tarroadhardsmoothsurfacebitumentar Unsurfaced roads
Based on functioning Express highway National highway(NH)-connecting state capitals, industrial centers airforce Foreign highways and capitals NH-47- Salem to Kochi NH 1- delhi-Ambala –Amritsar NH 3- Bombay Agra road
State highway(SH)-m connecting state capital to district head quarters and major cities of the state- maintained by state PWD,Example Main Central roadMC MC- Angamali to Thiruvananthapuram Major district roads(MDR)- connect areas of production market or to national and state highway act as feeder roads Other district roads(ODR) Village roads(VR )
Based on structural performance flexible pavements wheel loads are transferred by grain-to-grain contact of the aggregate through the granular structure. The flexible pavement, having less flexural strength, acts like a flexible sheet e.g. bituminous road rigid pavements wheel loads are transferred to sub-grade soil by flexural strength of the pavement and the pavement acts like a rigid plate e.g. cement concrete roads
Traffic volume: heavy, medium and light traffic roads. These terms are relative and so the limits under each class may be expressed as vehicles per day. Load transported: class I, class II, etc. or class A, class B etc. the limits may be expressed as tonnes per day.
WIDTH OF CARRIAGE WAY Single lane-3.75m Two lane without kerbs-7m Two lane with kerbs-7.5m Intermediate carriageway-5.5m Multiple lane pavements-3.5m
Road elements Superelevation Camber or cross slope
Superelevation outer edge of a road is raised keeping inner edge at the same level in order to counteract the centrifugal force
Camber Transverse slope provided to drain off water properly Water causes skidding or slippage