HIGHWAY ENGINEERING

Transportation has developed along three basic mode of transport are :-

1.  Roadways or Highways
2.  Railways 
3.  Waterways 
4.  Airways 

The comparison between various mode of transportation are as follows  :-

Over a period after the first world War, motor vehicles using the road increased and this demanded a better road network which can carry mixed traffic conditions. For the improvement of roads in india government of india appointed Mr. Jayakar committee to study the situation and to recommend suitable measures for road improvement in 1927 and reports was submitted in 1928 with following recommendations. 

1. The road development in the country should be considered as a national interest as this has become beyond the capacity of provincial  government and local bodies. 
2. An extra tax should be levied on petrol from the road users to develop a road development fund called  'Central Road Fund '.
3. A research organization should be instituted to carry out research and development work pertaining to roads and to be available for consultation.

1. Central Road  Fund was formed on 1st  March 1929.
2. The consumer of petrol were charged an extra levy of 2.64 paisa liter of petrol to build up this road development fund. 
3. From the fund collected 20 percentage of the annual revenue is to be retained as meeting expenses  on the administration of the road fund. 
4. The accounts of the CRF are maintained by the  Accountant General  of Central Revenues.

1. It is a semi - official technical  body formed in 1934 .
2. It was constitute to provide a forum of regular technical pooling of experience and ideas in all matters affecting the planning, construction and maintenance of roads in india. 
3. IRC has played an important role in the formulation of the 20 years road development plans in india. 
4. Now it has become an  active body of national importance controlling specifications guideline and other special Publication on various aspects of Highway Engineering.

1. CRTI  Was formed in the year 1950 at New Delhi. 
2. It was formed for research in various aspects of highway engineering. 
3. It is one of the national laboratories of the council of scientific and industrial research. 

There are various types of road patterns and each patterns has its own advantages and limitations.  The choice of road patterns depends upon the various factors such as :

• Locality 
• Layout of the different towns, villages, industrial and production centers 
• Planning Engineer 

The various road patterns may be classified as follows:

1. Rectangular or block pattern 
2. Radial or star and block pattern 
3. Radial or star and circular patterns 
4. Radial aor star and grid pattern
5. Hexagonal pattern
6. Minimum travel pattern 

• The KSHIP is an initiative of the public works department of the government of karnataka for improvement of road network of the state with world bank assistance. 
• The public works    department carried out strategic option study (SOS) during 1996 on a road network of 13,362 km comprising state Highways and major districts roads and the study identified 2888 km of road for prioritized improvements. 
• The world bank have extended technical assistance (T.A) loan of US $3.2 million for project preparation through the department 9f economic affairs of ministry of finance,  government of India for taking up the project coordinating consultancy (PCC) services to investigate and prepare detailed project report on the  2888 km and institutional development strategy  study.

1. Karnataka Road Development Corporation (KRDCL ) was incorporated on 21 st of July 1999 as a wholly government of karnataka company as per the provision of the company act 1956 .
2.  KRDCL is a company under the public works , ports and Inland water transport department. 
3. Since inception karnataka road development Corporation limited has strived to improve the road network and to establish connectivity to all the nook and corner of the state. 

The various factors control the alignment are as follows:-

1. Obligatory points 
2. Traffic 
3. Geometric Design 
4. Economics 
5. Other considerations

1. Obligatory points 

         These are the control points governing the highway alignment. This point are classified by into two categories.

1. Points through which the alignment should pass
2. Points through which the alignment should not pass

1. Points through which the alignment should pass :-

• Bridge site : The Bridge can be located only where the river has straight and permanent path and also where the abutment and pier  an be strongly founded. 

2. Points through which the alignment should not  pass 

• Religious places: These has been protected by the law from being acquired for any purpose. 

2. Traffic 

• The alignment should suit the traffic requirements . Based on the origin to destination data of the area the desire line should be drawn.  The new alignment should be drawn keeping in view the desire lines, traffic flow patterns. 

3. Geometric Design 

• Geometric design factors such as gradient,  radius of curve,  sight distance etc, also governs the alignment of the highway.  To keep the radius of curve minimum,  it may be required to change the alignment of the highway. 

4. Economics 

• The alignment finalized should be economical.  All the three cost I.e. construction,  maintenance,  and operating cost should be minimum. 

5. Other  considerations 

• The various other factors that govern the alignment are drainage considerations,  political considerations and monotony. The vertical alignment is often guided by drainage considerations such as sub surface drainage, water level, seepage flow,  and high flood levels. 

This is a penetration test developed by the California division of highway . For evaluating the stability of soil subgrade and other pavement materials.  The test results have been correlated with flexible pavement thickness requirements of highway and airfield.  CBR test may be conducted the laboratory in a prepared specimen in a mould or in situ in the field. 

Flexible pavement will transmit wheel load stresses to the lower layers by grain - to -grain transfer through the points of contact in the granular structure.  The wheel load acting on the pavement will be distributed to a wear area, and the stress decreases with the depth. Taking advantage of this stress distribution characteristics the lower layers will experience lesser Magnitude of stress and less quality material can be used.  Flexible pavements ate constructed using bituminous  materials. 

Types of Flexible pavement 

1. Conventional layered Flexible pavement
2.  Full depth asphalt pavement 
3. Contained rock asphalt mat (CRAM )

1.   Flexible pavement are layered  systems with high quality expensive materials are placed in the top where stresses are high, and low - quality cheap materials are placed in lower layers.

2. Full depth asphalt pavement are constructed by placing bituminous  layers directly on the soil subgrade . 

3. Contained rock asphalt mats are constructed by placing dense/open graded aggregate layers in between two asphalt layers.

The forms of bitumen are as follows:-

1. Cutback bitumen 
2. Bitumen Emulsion 
3. Cutback  Bitumen 
4. Bituminous  primers 
5. Modified Bitumen 

1. Cutback bitumen 

         Normal practice is to heat  bitumen to reduce its viscosity. In some situations preference is given to use liquid binders such as Cutback bitumen.  In Cutback bitumen suitable solvent is used to lower the viscosity of the bitumen. Cutback bitumen is used for cold weather bituminous  road construction and maintenance. 

2.Bitumen Emulsion 

         Bitumen emulsion is a  liquid product in which in which a substantial amount of bitumen is suspended in a finely divided condition in an aqueous medium and stabilized suitable material The Bitumen emulsion may be of anionic type or cationic type. Three types of bitumen emulsion  are available Rapid setting (RS), Medium setting (MS), and Slow setting (SS).

3.Cutback Bitumen 

       Cutback bitumen is obtained by blending bitumen blinder with suitable diluent or solvents in the required proportion to reduce its  viscosity tobthe desired range. Cutback is available in three types,  Rapid curing (RC), medium curing (MC), slow curing (SC).

4. Bituminous primers 

      In Bituminous primers the distillate is absorbed by the road surface in which it is  spread. The absorption there for depends on the porosity of the surface.