Will Hallett, 15, and his 72-year-old grandfather Barry Hearnshaw died after their car collided with a train at a level crossing in Emms Lane on Saturday morning.
The collision took place at 8.40am and since the incident detectives have been working to understand the circumstances leading to it.
Officers said they were looking to talk to motorists and pedestrians who were in or near the village that morning.
Detective Inspector Darren Gough, of the British Transport Police, said: “My thoughts remain with the family during what must be an incredibly difficult time. My team of officers continue to work hard to establish exactly what happened in the moments leading to this awful incident.
“Since Saturday’s incident, a number of people have contacted us and I am grateful for their help. However, I would now like to appeal to anyone else who was in Barns Green on Saturday morning and hasn’t yet spoken with police. In particular, I am looking to hear from motorists who may have dash cam footage of Barns Green, or Barns Green level crossing, on Saturday morning.”
Anyone with any information is asked to contact British Transport Police by sending a text to 61016 or by calling 0800 40 50 40 quoting reference 146 of 17/02/2018.