PITTSBURGH (AP) -- Autonomous truck company Aurora Innovation says it won't start hauling freight without humans on board until April of next year, a delay from previous statements that commercial service would begin by the end of 2024.

The Pittsburgh company on Wednesday said the April launch of driverless semis traveling from Dallas to Houston will be "modestly later" than the company had intended.

The company told investors on its third-quarter earnings conference call that it has made progress toward ensuring its trucks will operate safely.

Remaining obstacles are "primarily in the areas of some elements of surface street driving and some elements of construction that we see on the freeway," CEO Chris Urmson said. "We want to have extremely high confidence in the system as we as we go forward."

The company will start with about 10 autonomous tractor-trailers and move to "tens" of trucks by the end of next year, Urmson said.

"This shift to our timeline will have a negligible financial impact and does not affect our scaling efforts on our path to self-funding," Urmson said.

Aurora also intends to haul freight without human drivers from Fort Worth, Texas, to Phoenix later in 2025, Urmson said.

Aurora in August added nearly $500 million to its balance sheet with a capital raise in August, which the company expects to fund the initial phases of its strategy to scale up driverless trucking.