HYDERABAD, May 28: IIT-Hyderabad Tuesday said its
researchers have developed models and computational simulation
studies to predict performance of road surfaces or pavements
and compare these predictions with conventional road designs.
This research offers a route to accurate prediction of
pavement performance, which can help in construction of long
lasting roads in India, a IIT Hyderabad press release said.
This research work has been recently published in the
Journal of Transport Engineering, it said.
India has the second largest road network in the world
after the United States nd has about 4.37 km of roads per
1,000 people.
The past two decades have seen a drive to pave the Indian
roadway network, and as of 2016, 62.5 per cent of Indian roads
have been paved, it said.
Construction of the road surface or pavement is a complex
process as they should provide for comfortable riding quality,
good skid resistance, favorable light reflecting
characteristics and low noise pollution.
The pavement design is the first and essential step
towards building roads that can meet the needs of the traffic
demands as well as to balance the demand on natural materials
used in paving them, the release said.
Prof Sireesh Saride, faculty member, Department of Civil
Engineering,said a road surface or pavement typically consists
of superimposed layers of various materials above the natural
soil and helps in the distribution of the load of traversing
vehicles for a smooth ride.
There are two types of pavements rigid and flexible.
While rigid pavements are made of high strength concrete
to resist vehicle load directly, flexible pavements transmit
load downwards from the surface through successive layers of
materials.
“The advantages of flexible pavements are that they are
adaptable to stage-wise construction, can be made of low-cost
materials and can be easily opened and patched”, Saride said,
on the applicability of flexible pavements to Indian roads.
In modern pavement construction, accurate prediction of
pavement performance has become important in order to develop
robust design procedures.
“Reliability-Based Design Optimisation RBDO is a
modeling technique that combines optimisation approaches with
reliability assessment of structures”, he said.
His team used RBDO to predict safety of multi-layered
flexible pavement structures against fatigue and rutting
criteria, while simultaneously considering the variability
arising from individual design parameters.
The flexible pavement was modelled as containing four
layers subgrade, granular subbase, base, and bitumenous
layers.
Modelling studies showed that the bituminous layers
thickness and resilient modulus of the base layer are the most
influential parameters for the fatigue failure, it said.
The results of simulation studies were compared with data
from American Association of State Highway and Transportation
Officials (AASHTO) guide for the design of pavements.
“AASHTO overestimated reliability by 10-40 per cent
compared to RBDO because the former did not consider the
variability associated with geometrical and material
properties”, it said. (PTI)
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