The 35-year-old victim was attacked on the footbridge at lonely Reading West station at around 3.20am on Tuesday and The Chronicle can reveal it is the latest and most serious incident in a catalogue of crime over the past two years.
Passenger Samantha Clarke, 37, from Tilehurst Road, speaking to The Chronicle on the platform hours later, said: "I never feel safe here. It's a relief when the train comes.
"I'm shocked that someone has been attacked, but not surprised it's happened here."
In the gloom of Tuesday evening we found broken vodka bottles and beer cans dumped alongside the station fencing, and the eerie silhouettes of waiting passengers could just about be made out in the shadows created by the dim lighting.
The ticket office was shut because Reading West is only manned between 6.30-10.45am Monday to Friday. But a 25-year-old woman, who lives in Grovelands Road, explained this is the nightly reality of the station and said: "You're either alone waiting for the train, which is often delayed or cancelled, or there's people hanging around drinking.
"It makes you feel very vulnerable and scared about what could happen."
Paul Gouge, 60, from west Reading, added: "I understand why people, particularly women, feel threatened. I'm sure as I get older I will too."
Trains serving Newbury and Basingstoke stop there during the day and, apart from peak times, there are rarely many people on the platform. But 24 crimes were reported at the station in the 12 months to last September, and another 23 in the past year, mostly for trespass and anti-social behaviour.
This week's incident is the only reported sexual offence, but Reading West MP Alok Sharma is demanding improvements.
He said: "I am writing to First Great Western to see what can be done to improve lighting at the station and taking up the issue with the police to request a more visible patrol presence.
"We need to make sure that people feel safe and not intimidated."
Dan Paynes, spokesman for First Great Western, which manages the station, said: "We will be working very closely with the British Transport Police (BTP) and reviewing any necessary improvements, once we have more details."
Police want to speak to a white man with short dark hair, greying at the sides. He is 5ft 7ins tall and was wearing a dark grey short-sleeved top, pale-coloured trousers and black Converse-style trainers.
Inspector Chris Maddox, from British Transport Police at Reading, said officers do patrol the station, and added: "Crime at Reading West is very low but our priority is to make sure that people who use the railway in Reading are not only safe, but feel safe.
"It's therefore important that members of the local community tell us about any issues of concern they have in the area because this allows my officers and I to identify any problems and set about tackling them."