"cross on a" is not a grammatically correct phrase in English.
Instead, you could use the phrase "cross over a," as in "We crossed over a bridge to get to the other side."
TORONTO MAPLE LEAFS--Agreed to terms with D Cory Cross on a one-year contract.
Prince Charles and Camilla travelled one stop from Farringdon to King's Cross on a Metropolitan line train.
Isabelle, 9, was wearing a cross on a chain, a gift from her mother.
A convert to Christianity, he wore a gold cross on a chain around his neck.
The flag of St Piran, a white cross on a black background, flutters on every highway.
Instead of a cross on a hill, Minas has colonial towns loaded with Baroque-style churches.
Crossing elsewhere takes planning; at Ledra Street, you can cross on a whim.
"My father was a Muslim," said Ms. Behtic, wearing a Serbian Orthodox cross on a gold chain around her neck.
Dr. Christian F. Reisner is raising his electric cross on a thirty-six-story hotel which will house his church.
A second Westchester County man has been charged with burning a cross on a black family's front lawn.
Travellers from the south must cross on a flat barge propelled by motor-powered canoes lashed alongside.
