Even if there were public education programmes to "nudge" people off their phones, there would still be those who continued with "undesirable behaviour" or made mistakes, he explained.
"The important thing is that the system as a whole is designed to ensure the chances of serious injury is minimised," he said.
"Thus, if we are to provide information to people dependent on where they are looking [on the floor, if they are looking at their phone for example], it is vital that this information is placed at points where important decisions need to be made [for example about whether to cross]."
In Holland, HIG, a transport technology firm, has successfully trialled an LED light system that is embedded into kerbs at junctions. It flashes red to stop "zombie pedestrians" crossing the road when there is traffic.
It is currently being installed in six towns and cities in Holland and has garnered interest in the UK.
It is being taken up in cities and towns in Belgium, Sweden, Poland, New Zealand, Israel, Lithuania, Latvia and Brazil. Other cities, including Antwerp in Belgium and X'ian in China, have painted lines on the pavements to create text walking lanes.
Augsburg in Germany has installed traffic lights on the pavement so pedestrians on their phones do not step in front of trams.
Mettle, a London design company, is working with Direct Line and councils including Camden to develop intelligent video technology that analyses pedestrians' movements.
It can then tell whether they are elderly or distracted by a phone and flash warnings via lights embedded in the zebra crossing.
Helman, whose company advises the Department for Transport, the Highways Agency and TFL as well as governments around the world, said it was a "myth" people could "multi-task" walking and using their phone safely. Research has shown they are 18 per cent slower as well as being distracted, which increases the risk of accidents.
Official data show that pedestrian accidents are declining at half the rate of those of motorists, which the AA partly attributes to mobile phones.
In a Populus survey for the AA, at least two thirds of drivers said they had often seen pedestrians wearing headphones or distracted by their phone step into the road.
A survey last year by Deloitte found that 11 per cent of people admitted using their phone while crossing the road (equivalent to 4.5 million people). This rose to 21 per cent of 16- to 24-year-olds.
Edmund King, the AA's president, said: "People know drinking and driving is a problem. They know texting and driving is a problem. We haven't had such campaigns about zombie pedestrians. Maybe we need to raise the profile of it."