It happened around 1:25 p.m. at the intersection of Street Rd and Old Lincoln Hwy.
Police say their preliminary investigation found that the truck, driven by 31-year-old Andrew Ziemba from Meriden, Connecticut, was travelling eastbound on Street Rd approaching Old Lincoln Hwy.
Prior to approaching the intersection the traffic light may have turned red for the tractor trailer, police said.
At the same time a green BMW, operated by 21 yr old Danielle Felkner from Trevose, was travelling north on Old Lincoln Hwy approaching Street Rd.
Upon entering the intersection the BMW drove under the trailer portion of the truck causing the rear wheels to strike the BMW.
Felkner died at the hospital from her injuries.
The intersection was closed for approximately five hours while the accident was being investigated.
No drugs or alcohol appear to be a factor in the accident, police said.
Anyone with information is asked to call Bensalem AID Det. Vandegrift or Ofc. Jack Reheil at 215-633-3719.