Extra widening of highway

Extra widening

➤Extra widening refers to the additional width of carriage way that is required on a curved section of a road this widening is done due to two reasons

➤The First and the most important is the additional width required for a vehicle taking a horizontal curve. This is referred as mechanical widening.

The second is due to the tendency of the drivers to move away from the edge of the carriage way as they drive on a curve this width is referred as psychological widening.

From the calculation ,

⧫Mechanical widening :

       Mechanical widening                                                            

for single road lane

                  If there is a n lanes, the extra widening should be provided on each lane

 

                                  Then

For large radius ,   R2 = R ( which means radius of the curve )

 

Then mechanical widening 

                                              

  

⧫Psychological widening

 According to IRC,

 

                             Psychological widening 

                                   

Now total widening needed at a horizontal curve,

where (We) is Total widening