Express trains, like any other trains, require periodic maintenance for safety and operational reasons. However, the process of maintenance typically does not involve reducing the velocity of the trains specifically for that purpose.
Maintenance activities for trains are usually carried out during scheduled maintenance windows when the trains are not in service or during overnight periods when the demand is lower. These maintenance windows allow engineers and technicians to inspect, repair, and replace components, as well as perform routine maintenance tasks to ensure the trains are in optimal working condition.
While some maintenance activities may require the train to be taken out of service for an extended period, such as major overhauls or component replacements, these activities are typically planned in advance and do not involve reducing the velocity of the train while it is in operation.
However, it's important to note that trains, including express trains, do undergo regular inspections to ensure their safety and performance. These inspections may involve checking various components, such as brakes, wheels, couplings, and electrical systems. Inspections are often conducted at designated maintenance facilities or during routine stops at stations, but they are not typically the cause for reducing the velocity of the train during operation.
Overall, while express trains undergo maintenance activities to ensure their safe and efficient operation, these activities are usually planned in advance and do not require reducing the velocity of the trains while they are in service.