Never mind the dangers on the road, pedestrians are also suffering the consequences of mobile phone distraction.

Safety experts say people are tripping on kerbs, walking into traffic, even stepping into manholes as they chat or type while walking.

Now US technology companies are stepping in to help.

The tools include earpieces that allow users to talk their text messages and applications that make a screen transparent.

"I don't think we're going to eliminate people from walking into things outright and of course we want people to be responsible, but what we're trying to do is eliminate the friction point... and give the user back a little mental bandwith," said Travis Bogard, from Aliph, which makes bluetooth earpieces.

Their device incorporates voice-to-text technology that eliminates the need to look at the keypad to send an email or text message. It also has caller ID that speaks to the wearer and a function that allows wearers to call their contacts using their voice rather than their fingers.

"All of this gets rid of the need to touch your phone, which causes your eyes to move away from what's in front of you," Mr Bogard said.

Other programmes on the market tap into a smartphone's camera to beam an image of what is in front of the user over the message screen so typers can see what's ahead. They include Text Vision, Type n Walk and Email 'n Walk.

"See-through screens, yes, would solve part of the problem," said Clifford Nass, a professor of communications at America's Stanford University and one of the authors of a study on multi-tasking. "But there's still a second problem, which has to do with engagement of the brain."

The same applies to voice-to-text technology he said.

"It can help a little bit but the fundamental problem is that we're stuck with brains that can't do all that much when we're doing other things."

Two years ago, the American College of Emergency Physicians warned about the dangers of text messaging while walking, driving, biking and skating, based on anecdotal evidence from physicians.

Manhattan doctor Mark Melrose said he has seen many near-misses on pavements and heard of bad accidents.

"A friend almost walked right into a manhole while looking at her phone," he said. "Another friend was actually run over by a bike messenger. She wasn't paying attention, walked into the street and the bike messenger walloped her."

An Ohio State University analysis found that, over the past few years, the number of casualty visits resulting from pedestrian phone accidents has doubled year-on-year.

In 2008, just over 1,000 pedestrians were treated for injuries like walking into a post while texting or spraining an ankle after falling down while talking on a phone.

Jack Nasar, a professor of city and regional planning who supervised the study, said there were probably even more accidents that were never reported because people will not admit that is how they were injured or the injuries did not warrant a hospital visit.

Peter Loeb, an economist at Rutgers University who studied the effect of phones on pedestrian fatalities, said they can actually keep people safer because they get ambulances to the scene faster.