The National Capital Region Transport Corporation (NCRTC) has roped in experts to study the impact of an underground rapid rail transit corridor that is proposed to pass through the Delhi zoo on the vibration levels in the park, to ensure that animals are not disturbed during the construction of the line and operation of trains.
Close to 800 metres of the 107km-long Delhi-SNB Urban complex (Shahjahanpur-Neemrana-Behror) Regional Rapid Transit System (RRTS) corridor, which is part of the Delhi-Alwar RRTS line, will pass through the Delhi Zoological Park at a depth of 80 feet, as per the alignment proposed in the detailed project report. The alignment is yet to be approved by the central government.
The NCRTC has asked experts from the Central Road Research Institute (CSIR-CRRI) to do an assessment to gauge the impact of the vibration caused by the trains running underground as well as the construction work.“The stretch below the Delhi zoo will be constructed at a depth of around 80 feet. CRRI will carry out the vibration study in zoo premises after minimisation of Covid impact to establish the current baseline data for vibrations,” a spokesperson for NCRTC said
The Delhi-SNB corridor, along with the Delhi-Ghaziabad-Meerut line will provide seamless connectivity in the national capital region by linking cities in the Capital’s east — Ghazibad and Meerut, to those in south — Gurugram and Alwar. In Delhi, both corridors will originate from Sarai Kale Khan in south east Delhi. These corridors will also connect all these cities to All India Institute of Medical Sciences and Safdarjung, one of country’s biggest hospitals.
Of the total 107 kilometres, 83kms of the Delhi-SNB corridor will be constructed in Haryana, 22 kms in Delhi and 2 kms in Rajasthan. While the corridor in Haryana and Rajasthan will be mostly elevated, it will be completely underground in Delhi. Except for Sarai Kale Khan station, the remaining three stations at INA, Munirka and Aerocity will be underground.
Nasim Akhtar, senior principal scientist at transportation planning and environment division, CSIR-CRRI, said, “We will study the current ambient vibration levels in the zoo, both during day and night, and will ensure that they do not exceed the present levels during the construction and operation of the RRTS line.”
Akhtar said the first part of the study was done last year before the lockdown to record the day time ambient vibration levels. But the study had to be stopped after a lockdown was imposed again in April this year in view of an unprecedented rise in Covid-19 cases. Even though a gradual unlock process has begun, the government is yet to reopen the zoological park.
“The day time ambient vibration levels in the zoo is around 75-76 VdB. The vibrations are caused by a railway track nearby, and the movement of vehicles inside the premises. But we couldn’t do the study at night due to the lockdown. We will do the remaining part of the study once the zoo reopens,” he said.
When contacted, a senior Delhi zoo official said, “The matter was discussed last year. As of now, no permission has been given to carry out the study, as the zoo is closed due to the pandemic.”
Stressing on the need for night time study, Akhtar said, “The train operations will continue till late at night. The ambient vibration levels at night are much less than day time; we don’t want animals and birds’ sleep patterns to get disturbed because of train movement. Our recommendation regarding vibration control to NCRTC will be based on the vibration levels at night time.”
The NCRTC spokesperson said that it will be ensured that there is minimal impact of the train movement on the ground level. “The proposed tunnel is very deep in this zone and NCRTC is going to use special track structure to mitigate vibration,” he said.
Akhtar said there are a several technologies which can be incorporated during construction to minimise vibration. “According to the soil report from the area, there is sand filling till 17-20 metres depth. This is a good thing, as the vibration will get absorbed. If the night time level is less than 70 VdB, then we might recommend NCRTC to use technology such as a floating chamber to kill vibration at source.”
Anish Andheria, CEO of Wildlife Conservation Trust, said animals are far more sensitive to vibrations than humans, and if an alternate alignment of the corridor is possible, then it should be considered. He said if the current alignment is allowed, it should be ensured that there is minimal disturbance to the animals, especially during construction. “The executing agency should put in the public domain the technology they plan to use to minimise vibration impact from the perspective of animals. They should also look at similar projects carried out in other parts of the world to ensure that the most effective technology is deployed,” Andheria said.
While the Centre’s approval is awaited, NCRTC has started pre-construction work. “We are working on preparing the detailed designing of structures, geo-technical investigation work, initial pile load test, topographic survey work, shifting of utilities such as electric high-tension lines, water and sewer pipelines etc,” the NCRTC spokesperson said.
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