There are several reasons behind the cancellation of several trains on the Howrah-Chennai line in India. Here are some of the major ones:

• COVID-19 pandemic: With the rise in COVID-19 cases, the Indian Railways has had to cancel several trains to contain the spread of the virus.
• Technical issues: Trains get cancelled due to technical issues such as engine failure, unavailability of coaches, and maintenance work.
• Severe weather conditions: Trains often get delayed or cancelled due to heavy rain, fog, or storms.
• Protests and strikes: Train services can also be disrupted due to protests or strikes by various groups, which may affect the functioning of the railway system.
• Natural disasters: Natural disasters like floods and landslides can also cause railway tracks to get damaged or become impassable, leading to train cancellations.
• Low occupancy: If a train has low occupancy rates, the railway authorities may decide to cancel the service to save on costs.

These are some of the main reasons behind train cancellations on the Howrah-Chennai line and in India as a whole.