The incident occurred in 15603 Guwahati-Ledo Inter City Express and the accused jawan from the 299 Field Regiment, posted at Maiballa in Sonari under Sibsagar district of Assam, was arrested at Mariani station by railway police.
According to the FIR lodged by the woman, she was sleeping in the upper berth of an AC 3-tier coach, while the jawan was sleeping in the middle, her mother in the lower berth and her brother in a side berth.
The jawan also tried to prevent her from shouting by putting his hand on her mouth but she managed to raise an alarm causing her family members and other passengers wake up and catch the armyman, it said.
The jawan was handed over to Railway GRP Out-Post at Mariani under Tinsukia Railway Division in Jorhat district.
The accused was travelling back to Maiballa from Guwahati after official duty there, the sources added.