Light rail best suited for Metro Phase-2 section: Experts

The small radius curve and steep gradients were the deciding factors to freeze on a light rail transit system instead of a Metro rail for a 40 km network. The CTTP had suggested Monorail/ LRT while other experts had advocated extension of the Metro on this route. Two lines totaling 20 km, of the 60 km recommended for Monorail or LRT in the CTTP will be covered by Metro rail in its Phase 2. However, the remaining 40 km cannot be covered based on the terrain and traffic along the alignment.

A report prepared by Capita Symonds, a UK-based property and infrastructure consultancy firm, which the Infrastructure Development Department had hired as a consultant to explore whether monorail, light rail or another available technology will be suitable for this route, very clearly mentions the unsuitability of metro rail system on this corridor.

The maximum track gradient that metro (heavy rail) allows is 2.5% while the same allowed in LRT is 11% (depending on local conditions). The maximum track curve can be 25 meters in light rail and 150 meters in heavy rail. The Bangalore Metro has 4% as the steepest gradient between two stations and a maximum horizontal curve of 120 meters.

After metro was ruled out, the consultants considered monorail and LRT for this corridor and suggested that LRT would be more suitable on most of the parameters. While either monorail or LRT could be opted for considering passenger capacity, journey time and route characteristics and capital and operating costs, monorail was marginally better in terms of less shadow (of track beams) on the road. However, LRT was found more compatible with other rail systems in the city. LRT was also found more flexible in terms of infrastructure, accommodation of changes in the infrastructure as well as changes in the rail transport system in the future.

In future, materials supply will also be easier in LRT compared to monorail as each monorail has a unique design. Methods of construction of the deck is easier in LRT as it employs normal bridge construction techniques while monorail involves structural beams constructed to very high quality standards and tolerance.

Moreover, LRT also scored over monorail in method of emergency escape, torsional rigidity of deck on curves, straightforward switches, simple depot, easy access to the track for maintenance and accommodation of track side services. The consultants, after submitting the Technology Report is currently working on the Option Report to finalise the nitty-gritty of LRT project. Once the Option Report is ready and cleared, the consultants will prepare the DPR for LRT on this 40 km pre-fixed alignment.