Tumkur-Chitradurga section on NH-4, Karnataka

Project Title	Tumkur-Chitradurga Section on NH-4, Karnataka
Owner	National Highway Authority of India
Contractor Name	Modern Road Makers Pvt. Ltd.
Project Size	78,640. sqm. of fascia blocks
Location	Tumkur-Chitradurga Section from 75.00 km to 189.00 km of NH-4, Karnataka.
Maximum Height of Walls	9.7 meters
System Offered	Construction of RS Wall using StrataGrid™ as soil reinforcement + StrataBlock™
Consultant	ICT Pvt. Ltd.
Completion Year	2013

The section of NH 4 from 75.00 km to 189.00 km connects the thickly populated regions of Tumkur and Chitradurga in Karnataka. The National Highway Authority of India under NHDP Phase V adopted this section for widening to six lanes.

Considering the terrain and sub-soil conditions, it was necessary to design and construct the approaches on filled up / raised foundations. The conventional solution of RCC retaining walls was costlier and time consuming, besides possible disruption of traffic. Reinforced soil (RS) walls to support the approaches proved to be an optimum solution.

RS walls were constructed using non plastic soils available in the region, StrataGrid™ PET knitted geogrid soil reinforcement, and StrataBlock™ precast segmental concrete blocks as fascia. The founding levels of these walls had to be raised from technical requirements and to economies on the cost of construction. Berms were provided 1 to 2 meters above the existing ground levels. The reinforced soil material was also used for these berms. Construction of both RS walls and berms was carried out with stringent quality control. The schematics of the RS system is shown in below.

Use of StrataGrid™ geogrids and StrataBlock™ fascia resulted in cost reduction as compared to the conventional RCC retaining walls. The system also facilitated easy construction of roads within minimum time.