Ministers need to spend billions of pounds to improve the road network if they want to avoid a public safety crisis brought about by the legalisation of e-scooters, it has been claimed.

Last week, the government announced it would hold a consultation on the introduction of the battery-powered scooters to British roads – something that has until now been resisted despite their popularity in more than 100 cities globally including Paris, Copenhagen and San Francisco. The Department for Transport is expected later this month to pave the way for the first street trials for e-scooters.

Advocates see e-scooters as part of the solution to pollution, congestion and crammed public transport. But safety campaigners, cycling charities, head injury specialists and even e-scooter hire firms all agree that riders are vulnerable and should be separated from traffic, ideally in cycle lanes.

Rachel White, head of public affairs at Sustrans, the cycling and walking charity that is broadly in favour of e-scooters, said that unless the government invested in protected paths, “conflict” would inevitably occur.

“If you don’t create safe space on the roads for e-scooters, you will get them being used on the pavements and that’s where you start to get conflict with pedestrians, vulnerable road users, children, anyone with sight loss, any disability, older people,” she said.

“They’re quiet and you can’t really hear them coming. When you see people cycling on the pavements, nine times out of 10 it’s because they don’t feel safe on the road. You’ll get the same with e-scooters.”

YouTuber and TV presenter Emily Hartridge died last year when her e-scooter collided with a lorry in south London. Photograph: Jeff Spicer/Getty

Joshua Harris, director of campaigns at road safety charity Brake, said that although car alternatives were vital, “the safety of e-scooters and their impact on all road users must be assured before they are permitted on our roads”.

Until now, e-scooters in Britain have existed in a limbo – available for purchase on the high street but illegal to ride on both pavements and roads. But even with small numbers of people riding them, doctors are beginning to see serious injuries.

Last year, Emily Hartridge, a YouTuber and TV presenter, died after a collision with a lorry in Battersea, south London.

Chris Uff, a neurosurgeon at the Royal London Hospital, said his team had treated four patients last summer with “fairly severe head injuries, either after coming off e-scooters or being hit by people on them”.

He said helmets were essential. “The impact of brain injury is devastating,” he said. “Hitting your head by falling from an e-scooter will deliver the same amount of force as one of Frank Bruno’s knockout punches.”

Other countries have already learned the perils – and advantages – of the vehicles. “Dockless” scooters, which are available for hire from companies like Lime, Bird and Spin, are part of normal life in many European and US cities.

In the US, a study showed there had been about 10,000 serious injuries a year, with a third of victims suffering head trauma, twice the rate suffered by cyclists. Peter McCabe, chief executive of Headway, the UK brain injury association, said he expected the government to tell e-scooter riders they should wear helmets. “It is surely common sense for all e-scooter users to protect themselves by wearing helmets, which evidence shows can save lives and prevent lifelong disability,” he said.

Demonstrators outside Downing Street calling for the legalisation of e-scooters on UK roads. Photograph: Tom Horton/PA

Arnaud Kielbasa, a co-founder of French campaign group Apacauvi, which has been campaigning for tighter restrictions in Paris, believes Britain should learn from mistakes made across the Channel. He said that “in Paris, dockless e-scooters are really a cancer” because of the problems they cause on the pavement – “elderly people who are knocked over, women with pushchairs who can’t [get] through. It is really a big, big problem. Since they arrived in France, more than 15 people have died in the streets, victims of e-scooters.”

Harry Porter of hire company Bird said it had solved the problem of inconsiderate parking in Paris and other cities by working with officials to set up dedicated parking spots. Riders get discounts for parking in the right places.

“Cycle lanes are absolutely key,” he said. “With any accident that happens it’s very rare that it’s in a segregated cycle lane in the city.”

He said Bird could geofence dangerous roads so that a scooter would stop working if someone tried to ride down it, and speeds can be limited by GPS tracking.

Matt Turzo, the chief operating office of Wind, said scooter firms needed to work with local authorities “to ensure the right infrastructure for the city”: “The cities with the strongest e-scooter networks are those where service providers and local authorities work side by side.”