Capt Suporn Meangkai of the Thalang Police was informed of the accident at 9:40pm.
Officers arrived at the scene, near the U-turn in Muang Mai, to find a the bicycle on the road and the car that struck it parked nearby, with the car driver standing by.
The woman, identified as Sasiphat Thitiphatmetan, was dead at the scene, noted police.
The driver of the car, Witoon Uthatchakon, told police that he was driving southbound when the bicycle came crossed into his lane from the left, heading to the far side of the road.
Mr Witoon said he could not swerve or brake in time to avoid hitting the bicycle, and the woman riding it.
After having Mr Witoon conduct a breath test at the scene, officers took him to Thalang Hospital to be tested for drugs and alcohol, Capt Suporn said.
“He tested negative,” he confirmed.
However, Capt Suporn said he had yet to conclude his investigation into the accident.
“I have had the vehicle brought to the police station for further inspection,” he said.
“I have also contacted Ms Sasiphat’s son and informed him of the incident. He was in another province, but is on his way now,” Capt Supron added.