100th KRIDE Board Meeting

[Audio] Elimination of Level Crossings through RUB construction made feasible by raising of Embankment (Hebbal-Banaswadi Section of SWR).

[Audio] Outline Brief of Reference Project (Hebbal-Banaswadi Section, SWR) Concept Plan & Technical features of Project Methods of Elimination of Level Crossings Merits of LC Elimination by Embankment raising Constraints of proposed Methodology Challenges & Pre-requisites of design and maintenance.

[Audio] Brief of Reference Project (Hebbal-Banaswadi Section, SWR) Bengaluru Suburban Railway Project (BSRP), being executed by K-RIDE, aims to improve rail connectivity in Bengaluru with 4 corridors. Corridor-2 has total 4 tracks (BSRP- 2, IR- 2), running from Benniganahalli to Chikkabanavara, 25.58 km. The project involves 8.03 km of elevated track and 17.55 km of at-grade track. It features 6 level crossings (LCs) between Hebbal and Banaswadi. Project seeks to eliminate these level crossings through raising of formation and thus creation of Rail Under Bridges (RUB), along with additional underpasses for public convenience. Work is in progress and is being executed by L&T..

[Audio] Corridor-2 (25.577km) Formation Raising 5.964 Km.

[Audio] HEBBAL BANASWADI 6 Nos LCs (within a length of 2.5km) being Eliminated by raising the formation level.

[Audio] Cross-Section of Formation. Cross-Section of Formation.

[Audio] Concept Plan & Technical features of Project Raising of formation up to 6m Existing 6 level crossings will become RUB 5 additional underpasses created for public convenience No track drainage problem at RUBs during monsoon Smooth and safe road and rail operations.

[Audio] Concept Plan & Technical features of Project Formation for 04 tracks (BSRP-2, IR-2) between Hebbal and Banaswadi stations to be raised up to 6m, with RCC retaining walls on both sides. Annual rainfall in Bengaluru is more than 800mm. Proper drainage of formation becomes critical in such scenario. Following measures are being taken: Sloped formation profile (1 in 30 cross slope) to ensure proper drainage. Geo-membrane below the blanket/crushed stone layers to enhance stability. Geo-composite drains along the retaining walls in place of backfill material..

[Audio] Longitudinal (side) drain at formation level, all along, with sump at every 200-300m. Backside outlet drain at Toe level of retaining wall to collect drainage from formation and embankment, with outfall in nearby minor bridge (available at 200-400m). Weep holes provided in the retaining walls as additional drainage measure. RUB structure consists of precast segmental as well as cast-in-situ RCC box RUB is designed for 25t loading-2008 standards..

[Audio] GEOMEMBRANE- HDPE (2mm) GEOCOMPOSITE DRAIN.

[Audio] Methods of Elimination of Level Crossings RUB (Road Under Bridge): There are feasibility issues w.r.t. Land availability, Drainage & Sight Distance for Road users ROB (Road Over Bridge): Cost, Time, Encroachments or Dense habitation on approaches, Long Ramps, Feasibility of connecting multiple approach roads Merger with adjacent existing LC gate: LC diversion cost & recurring maintenance cost, Restricts future expansion of Railway network Raising of Embankment to provide RUB at existing road level: Suitable where number of LCs in block section is large, alignment lies within city limit and there is very heavy road traffic Elevated track on viaduct: Prohibitive Cost, Maintenance issues, Encroachments or Dense habitation along Railway boundary.

[Audio] Merits of LC Elimination by Embankment raising Faster execution, better quality control due to green field working. Minimum disruption to rail and road traffic. Cost of construction is less compared to elevated track. Waterlogging issues in RUBs are addressed with suitable surface drain network & outfall points, re-grading of approach road is not required. Improved road safety owing to straight approaches and elimination of dead/blind zones. Reduced land requirement for RUB approaches. Protection of track against trespassing (human/cattle), water logging in city areas, garbage dumping.

[Audio] Constraints of proposed Methodology Suitable in Multi-tracking projects only. Raising of existing Railway bridges particularly Important/Major bridges and important minor bridges is not easy. Costly in comparison to conventional RUB work. Disruption to traffic will be severe and of longer duration in case there is any issue related to formation (or drainage). Formation rehabilitation will be difficult in such case. Drainage issues due to raising of embankment..

[Audio] Challenges & Pre-requisites of design and maintenance Yard remodeling at both ends of block section may be required to connect new tracks for diversion of train operation from existing tracks. Replication of existing signaling system will be required to divert train operation from existing tracks to new tracks (and also additional traffic handling facilities in both yards which may finally become infructuous viz common loops, additional cross overs, single line signaling on new track in case of doubling or; double line signaling in case of quadrupling of existing double line). Additional Utility Shifting (S&T, TRD, Elect-G, Engg, etc) & additional cabling work due to raising of existing track(s) and/or due to raised embankment for additional tracks. In-service functional aspects of Geocomposite drains..

[Audio] Design of RCC retaining walls for worst combination of loads including pore water pressure condition. Maintenance issues due to limited access & material stacking space. Handling/rescue of accidents/derailments due to limited access & other site/space constraints..

[Audio] Weep holes are not provided in the base portion of retaining wall. Approx. 1.5-2.0m depth of retaining wall is left without the weep hole. Weep Holes shall be continued up to top of base slab..

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[Audio] Key Observations of Site Design of longitudinal drain must accommodate expected surface runoff during severe rainfall, with a self-cleansing velocity to ensure efficient drainage. Outlet arrangement of water from chambers to outside drain shall be ensured with proper fixing of pipe with retaining wall. Backside drain shall also be checked for adequate capacity and proper slope. Retaining wall is designed without pore water pressure. Hence role of geo-membrane and geo-composite drain becomes more crucial for efficient drainage of water. As detailed by K-RIDE project team, Standard Penetration Tests (SPT) and Plate Load Tests (PLT) have been conducted at intervals of 200-300m along the alignment.

[Audio] Key Observations of Site The ground subsoil investigation is conducted as per RDSO Specification No. RDSO/2020/GE:IRS-0004. Suitable anchoring/stitching arrangements shall be ensured to prevent toppling of last segments over the running track. RCC box segments will be anchored with the retaining wall from back side by doweling of bars. Wing wall may be provided at both the approaches. Major Bridge No. 560 (1x30.5 composite girder), the design includes transition system at the bridge approach, as per the latest GE: R-50 (Rev-2). Trolley refuges will be provided as per IRPWM..

[Audio] A detailed Inspection Test Plan (ITP) and Quality Assurance Plan (QAP) is prepared, same shall be reviewed by OL periodically to ensure that the work adheres to the required quality standards. Formation width is approx 25m (4 tracks). Cross slope of 1 in 30 is provided from middle of the formation width, causing ballast cushion more than 500mm at the farthest track from middle. In order to maintain proper ballast profile suitably designed ballast wall may be provided both side During trolley inspection it was observed that weep holes are not provided in the base portion of retaining wall. Approx 1.5-2.0m depth of retaining wall is left without the weep hole. Ensure weep holes shall be provided up to the haunch portion. Foundation of Retaining wall near Ch 5+400m is slightly exposed..

[Audio] Suggestions/Mitigation measures RDSO Specification No. RDSO/2018/GE:IRS-0006, March 2019 shall be followed for testing, handling, packing and installation of Geo-composite drain. IS Specification 16352:2020 may be followed for Geo-membrane. Drainage plan of complete section including RUBs shall be prepared and got approved by OL. A sand layer may be introduced between the crushed stone and geo-membrane to avoid punctures. A detailed method statement must be developed for the installation of geo-composite and geo-membrane layer, and same should be approved by the OL..

[Audio] Utility shifting plan for the section must be approved from OL before execution of any work. RSI analysis (Rail Structure Interaction) of Major Br. No. 560 (1x30.5m CG) must be performed before approving structural drawing for the bridge. RSI analysis is yet to be done. A proper maintenance plan should be prepared, with mechanized systems for both planned and casual maintenance and same shall be approved from OL. Additional formation width in isolated locations for evacuation of passengers and stacking of P-way materials. Disaster Management Plan, including action plan for derailment handling, shall be formulated for the section and got approved from safety department of OL..

[Audio] Guard rail shall be provided continuously through out the section. Since this type of drainage system is implemented on such a large scale, an instrumentation plan should be established to monitor the system’s performance and reliability, including Piezometers for checking pore water pressure during the monsoon. In case of malfunctioning of Geo-composite drain and Geo-membrane layer, alternate drainage arrangement scheme shall be prepared in advance to tackle any future exigency..

[Audio] Geo-composite drain Geonet bonded with non-woven geotextile layers on both sides Widely used in Flyovers and other Railway structures for effective drainage RDSO specification available Provided Adjacent to retaining wall to drain out seepage water in embankment Water is collected and disposed off through 150 mm dia perforated PVC pipes wrapped with geo composite at the bottom.

[Audio] Geo-membrane High density polythelene (HDPE) material Geosynthetic with very low permeability Modern and effective solution to avoid water ingress Very durable.