Highway Engineering

Highway engineering is an engineering discipline branching from civil engineering that involves the planning, design, construction, operation, and maintenance of roads, bridges, and tunnels to ensure safe and effective transportation of people and goods.

Highway Development And Planning 

Historic Development 

 Early Development:-The earliest modes of travel obviously  was on foot track. animal are also used for transport mean and materials. later simple animal drawn vehicle were developed and this became a common and popular mode of transportation for a very long period after the invention of wheel. This bought up the necessity to provide a hard surface for the vehicle to move on.such a hard surface is believed to existed in a mesopotamia in a period of 3500 B.C.

Roman Road:-

Many of the early roman roads were of elaborate constructions.some of these roads are still in existence after the period of over 2000 years.During the period of roman civilization many road were built of stone block of considerable thickness.

The main features of Roman roads are :

1. They were built straight regardless of gradient.
2. The soft soil was excavated and remove till hard stratum was reached.
3. The total thickness of the construction was as high as 0.75 to 1.2 meters at some places, even through the magnitude of wheel loads of animal drawn vehicles was very low.

Tresaguet method of Road Construction:-After the fall of the roman empire,their technique of road construction does not gain popularity in other countries.
pierre Tresaguet (1716-1796)  developed a improved method of construction in France by the year of 1764 A.D. 
The main Features of tresaguet method  are :

1. The thickness construction need only in the order of 30 cm.
2. The subgrade was prepared and a layer of large foundation stones were laid on edge by hand.
3.  cross slope provided is 1 in 45 to the surface.

Metcalf method of Road Construction:- John Metcalf (1717-1810) was engaged on road construction work in England during the period of when Tresaguet was working in France.Metcalf was responsible for the construction of about 290 km of rad in northern region of England.As Metcalf was blind much of his work was not recorded.

Telford Method of Road Construction:- Thomas Telford (1757-1834) began his work in early 19th century. He was the founder of institution of Civil Engineers at London. 
The main features of Telford method are:-

1. A level subgrade was prepared to a width of about 9m.
2.  Large foundation stones of thickness 17 to 22 cm were laid .

Macadam method of Road Construction :-

John Macadam (1756-1863) put forward a entirely new method of road construction as compare to all previous methods. The first attempt to improve road condition was made by him in 1815.

The main features of macadam method are :-

1.  Sub grade is compacted and prepared with a  cross slope of 1 in 36 up to a desire width (about 9 m ) .
2. Broken stone of strong variety, all passing through a 5 cm sieve were compacted to a uniform thickness of 10 cm.
3. the second layer of strong broken stones of size 3.75 cm was compacted to thickness of 10 cm.
4. The top layer consist of size less than 2cm compacted to a thickness of about 5 cm and finished so that cross slop[e of pavement surface was also in 1 in 36.

       

 

Classification Of Roads:-

1. Based on Weather:-

   1. All weather Road
   1. Fair weather road  
    
2. Based on type of Carriage way or Road Pavement:-
   
   1. Paved Road
   2. Unpaved Road  

3. Based on Type of Pavement Surfacing:-

   1. Surfaced Roads
   2. Unsurfaced Roads   

4. Based on Method Of Construction:- 

   1. Traffic Volume (Vehicle) :-

      • Heavy Traffic Road
      • Medium Traffic Road
      • Light Traffic Road 

   2. Load Transported or Tonnage :-

      • Class I or Class A 
      • Class II or Class B etc

   3. Location and Function.  

Modified Classifications Of Road System

1. Primary System

   1. Expressway
   2. National Highway (NH)

2.  Secondary System

   1. State Highway (SH)
   2. Major District Roads (MDR)

3. Tertiary Systems or Rural Roads

   1. Other District Roads (ODR)
   2. Village Roads (VR) 

   Classification Of Urban Road 

   1. Arterial Roads
   2. Sub arterial Roads
   3. Collector Streets
   4. Local Streets  

 

 

surveying :basic info

SURVEYING IS THE ART OF DETERMINING RELATIVE POSITIONS OF POINTS ON ABOVE OR BENEATH THE SURFACE OF EARTH BY MEANS OF DIRECT OR INDIRECT MEASUREMENTS OF DISTANCE,DIRECTION AND ELEVATION.

In simple word surveying is the technique and science of determining the terrestial and three dimensional position of points,distance and angle between them.
A land surveying professionals is called a land surveyor.

 History:-
         

Ancient surveying

                 The basic surveyance occurs when humans built first large structures.
We can predict that the surveying take place firstly at stone age by our ancestor.
In ancient Egypt, a rope Stretcher would use simple geometry to re-establish boundaries after the annual floods of the Nile river. The almost perfect squareness and north-south orientation of the Great Pyramid of Giza, built c. 2700 BC, affirm the Egyptians' command of surveying. The Groma instrument originated in Mesopotamia (early 1st millennium BC).

Modern surveying

Abel Foullon described a plane table in 1551, but it is thought that the instrument was in use earlier as his description is of a developed instrument.
Gunter's chain was introduced in 1620 by English mathematician Edmund Gunter. It enabled plots of land to be accurately surveyed and plotted for legal and commercial purposes.

 

 There are  some surveying equipment listed below.

Theodolite :- Theodolite that measure horizontal angle is created by Joshua Habermel  with

 a compass and tripod in 1576.Leonard Digges described a Theodolite in his book A geometric practice named Pantometria (1571). Johnathon Sission was the first to incorporate a telescope on a theodolite in 1725.

Measuring Tape :- A measuring tape is the primary tool for surveying without measuring tools we can't measure anything.A tape measure or measuring tape is a flexible ruler. It consists of a ribbon of cloth, plastic, fibre glass, or metal strip with linear-measurement markings. It is a common measuring tool. Its design allows for a measure of great length to be easily carried in pocket or toolkit and permits one to measure around curves or corners.The first record of a people using measuring device was roman.They use marked strips of leather, but this was more like a regular ruler than a tape measure.

Total Station:-A total station or TST (total station theodolite) is an electronic/optical instrument used in modern Surveying and building construction. The total station is an electronic Theodolite (transit) integrated with an electronic distance meter (EDM) to read slope distances from the instrument to a particular point.

3D scanners :-A 3D scanner is a device that analyses a real-world object or environment to collect data on its shape and possibly its appearance (e.g. colour). The collected data can then be used to construct digital three-dimensional models.

 Principle of surveying:-

Following are the principles of surveying which would be kept in mind while determining relative position of points on the surface of earth.

1. To work from whole to part.

2. Fix the position by two independent process.