The Trump administration unveiled updated safety guidelines for self-driving cars Tuesday in an attempt to clear barriers for automakers and tech companies wanting to get test vehicles on the road.

U.S. Transportation Secretary Elaine Chao announced the new voluntary guidelines during a visit to an autonomous vehicle testing facility at the University of Michigan.

"Our country is on the verge of one of the most exciting and import developments in transportation history," Chao said.

The new guidelines update policies issued last fall by the Obama administration. Under the Obama administration's largely voluntary guidelines, automakers were asked to follow a 15-point safety assessment before putting test vehicles on the road.

The guidelines also made clear that the federal government — not states — would determine whether the vehicles were safe.

Regulators and lawmakers have been struggling to keep up with the pace of self-driving technology. They are wary of burdening automakers and tech companies with regulations that would slow innovation, but they need to ensure that the vehicles are safely deployed.

There are no fully self-driving vehicles for sale, but autonomous cars with backup drivers are being tested in numerous states, including California, Nevada and Pennsylvania.

Autonomous vehicle developers, including automakers and tech companies like Google and Uber, say autonomous vehicles could dramatically reduce crashes, but they complain that the patchwork of state laws passed in recent years could hamper their deployment.

Early estimates indicate there were more than 40,000 traffic fatalities in the U.S. last year. The government says 94 per cent of crashes involve human error.

Consumer and safety advocates are concerned that untested, experimental cars could get on public roads too soon, and accidents could undermine public acceptance of the technology.

The new guidelines encourage companies to put in place broad safety goals, such as making sure drivers are paying attention while using advanced assist systems.

The systems are expected to detect and respond to people and objects both in and out of its travel path "including pedestrians, bicyclists, animals, and objects that could affect safe operation of the vehicle," the guidelines say.

There is a 12-point safety checklist, but the government makes it clear that the guidelines are voluntary and not regulations.

"While these assessments are encouraged prior to testing and deployment, NHTSA does not require that entities provide disclosures, nor are they required to delay testing or deployment," the guidelines say, referring to the National Highway Traffic Safety Administration.

Chao's appearance at Mcity, an autonomous vehicle testing facility at the University of Michigan, came the same day that the National Transportation Safety Board was debating whether Tesla Inc.'s partially self-driving autopilot system shared blame for the 2016 death of a driver in Florida.

So far, the government has mostly sided with automakers and tech companies.

The U.S. House voted last week to give the federal government the authority to exempt automakers from safety standards that don't apply to the technology. If a company can prove it can make a safe vehicle with no steering wheel, for example, the federal government could approve that.

The bill permits the deployment of up to 25,000 vehicles in its first year and 100,000 annually after that.

The Senate is now considering a similar bill.

Under the Obama guidelines, automakers were asked to document how self-driving cars detect and avoid objects and pedestrians, how they are protected against cyberattacks and what sort of backup system is in place in case the computers fail.

Obama's policy also required the government to consider adopting new authorities, including methods to test autonomous vehicles before they were allowed on the road.