The train belongs to SWR,with Primary Maintainence at Bengaluru. Chennai is in SR. However,Railways is railways. SWR and SR should come to a proper agreement. Even if 12628 arrives at say 19:00 clock....5 hours maintainence time will be available.They can do neccessary watering,safety checks and cleaning in this available time.If work is pending,precautions can be taken like restricting the train's max speed limit,as even if the train is 1-2 hrs late if it starts at right time,it won't be as inconvinient as doing a day time travel.The work pending can be handed over to MAS.