Landslide Mitigation - Semi-quantitative Approaches for Landslide Assessment and Prediction - page 246

8.3.11 Road Diversion to Avoid the Paglajhora-Sinking Zone

The problem of the road subsidence and sinking in the Paglajhora region (Gayabari-
Mahanadi-Giddapahar Sector) has been a severe bottleneck since long along the
N.H.-55. The N.H.-55 (Hill Cart Road) has been constructed in the British regime
with a very low gradient up to the fabulous hill city Darjeeling. To take advantage
of this low gradient (around 1:50) road bench, the Himalayan toy train tract was
also planned and aligned by them along the hill cart road. With time it has become
the busiest route to transport heavy traf

c to the remote areas of Darjeeling district,
W.B. Till date, the journey path of the Himalayan queen (Darjeeling Himalayan toy
train) has somehow been maintained to attract the tourist from all over the world.
Recently, this toy train has become christened as World Heritage Site by UNESCO,
and the maintenance procedure has become more active as well. As most of the land
slide occurs along Hill Cart Road (NH-55), and a huge amount is spent for the Post-
Slide Management, an attempt for pre-slide management of the susceptible areas
has to be introduced with immediate effects with less efforts and investment.
A sector wise job assignment has to be made for regular supervision of the slope
stability and a serious drive for pre-slide management of potential slope failure
zones are to be introduced and it should be considered as emergency as that in post
slide condition. For all monitoring programme, it is essential that accurate records
are kept about various landslide inducing parameters and rate of change of the
landslide affected areas by thorough inspections. Not only will monitoring systems
allow the implementation of an emergency response if required; they can cite
baseline of information and can increase the knowledge about the landslide prone
area, the Shivkhola Watershed.
As new alignment of the rail bench from other route at such a low gradient to
avoid the 2 km long problematic stretch of Paglajhora Sinking Zone (Fig. 8.20 )is
perhaps not a pragmatic proposition. Though, an alternative route of heavy traf

c
can be possible in the area. Already a by-pass route has been developed which is
joining Giddapahar with Gayabari avoiding Paglajhora. The said road is aligned
along a ridge line, baring steep gradient with numerous zigs and is suitable for only
small/light vehicle. An alternative road from Rohini T.E. to Kurseong has been
implemented and the upslope vehicles are passing along this road and thus the
stress has been reduced a bit on NH-55 as well as on affected sites of Paglajhora,
Gayabari, and Tindharia etc. But the imposition and strict implementation of
restriction on heavy vehicle can only assure relief on these instable areas along the
Hill Cart Road (NH-55).

8.3.12 Construction and Maintenance of Buildings

Landslide in the Shivkhola Watershed is a common problem as it damages roads,
buildings and other infrastructure but much can be done to mitigate such damages