It also will have decisive impact on the landscape and urban environment of Bangalore. Therefore, the design concept of guideway shall be selected from those proven in the developed countries to meet such requirements.
The basic design described in Chapter 6 was selected after a number of plans for upper structure, sub-structure and foundation were discussed.
As earthquakes are rare in Bangalore, seismic loads were not assumed in guideway design.
6.1.2 Guideway Plan
As mentioned above, the elevated guideway which consists of foundation, pier supports and upper structure girders, was selected for the Bangalore LRT project.
In discussions on methods of design and construction, it was determined to construct the guideway in a short period of time in order to minimize the disturbance of surface traffic. To do this, UBTSL adopted the incremental launching girder method. This is called a block construction method in Japan. In this method, precast fan type segments (3 m or 4 m wide) are manufactured and fabricated at a manufacturing base. They are transported to the construction site and set in the girder position using an incremental launching girder to complete the guideway by the post-tension method.
(1) Support (Appendix 6.1-1, 2)
The type of foundation depends on soil properties. At the site of the Bangalore LRT project, hard base rock (granite) lies under the surface layer which extends to a maximum depth of 20 m. Precipitation is low and ground water level is low. Thus, the site has comparatively good properties for foundation construction work.
Therefore it was decided to use support piles along the entire route that reach the hard base rock and are more reliable than friction piles.
The standard support structure is composed of T-type circular single columns planted at the street center. Where T-type single columns cannot be used due to spatial or geometrical constraints, portable rigid frame columns supported at street shoulders will be used. Thus, in principle, single columns will be used in streets wider than 12 m and portal rigid frame columns in narrower streets. Depending on street conditions, howeve1 portal rigid frame columns will be used in place of single columns even if the street width is more than 12m.
Two types of foundation will be used: pile foundations (with precast piles or cast-in- place piles) and direct foundations. This LRT project will use cast-in-place support
