They also want to speak to a male driver who gave the girl and her friend a lift out to Tramore earlier on Sunday evening. Despite intensive appeals, few people have come forward with information on the crime, investigating sergeant John McDonald said.
At least five other passengers were on the bus with the girl and her friend. Not all of these have yet come forward, the sergeant said.
The bus was the last service out of Tramore on Sunday night and left at 11.35pm, arriving into a bus stop just outside Superquinn on the edge of the city at 11.55pm.
The girl is believed to have been followed into a laneway near the bus stop and attacked.
Gardaí were alerted at 12.45am when the victim raised the alarm at a house in the nearby Cherrymount Estate. Despite several appeals, gardaí have not yet managed to trace all of the passengers on the bus.
“We put out several appeals but have not had a great response so far,” Sgt McDonald said.
“We are very anxious to speak to anyone who travelled on the last bus out of Tramore on Sunday night or who was in the general area around Superquinn and the RFC.
“Very few people have come forward so far. We know there were a number of people on the bus and we want to speak to all of them so we can further the investigation.
“We would be very anxious to trace a driver who provided a lift to two girls from the Superquinn/RFC area as far as the Esso garage across from the GAA pitch on the main Waterford to Tramore area between 8.30pm and 9pm.
"This man is not a suspect or anything. He simply provided a lift but we want to speak to him so we can piece together the events of that night,” Sgt McDonald added.
The attack along a secluded, shady passageway in the John’s River area close to Superquinn happened just after midnight on Sunday. The victim’s friend had gone ahead of her towards Cherrymount shortly before she was attacked.
Gardaí investigating the assault can be contacted on 051 305300 or on the Garda confidential line 1800 666111.