But often it will be the Highways Agency's traffic officers who are there to administer basic first aid, redirect the traffic or make the area safe, before anyone else.
Northamptonshire's team of officers patrol the M1 from just north of junction 14 to just south of junction 20, and also the M45 and parts of the A14.
Traffic officer supervisor, Colin Dent, told the Chronicle & Echo: "The most important thing we do is look after the welfare of the travelling public; all aspects, including managing accidents and breakdowns.
"The most enjoyable part of it is meeting the people, and being out there knowing that you have made a significant difference to somebody's day.
"We help everyone from young mothers with little children to hard-nosed van drivers who don't always appreciate what you are trying to do."
On a typical day, the officers deal mostly with routine breakdowns and motorists stranded on the hard shoulder and organise their recovery.
Removing damaged and abandoned vehicles is another job, as is providing road closures.
And about 15 to 20 per cent of their time is spent attending road accidents, where they manage the traffic around the scene.
Mr Dent said: "Mainly, it means stopping and directing traffic and making the scene safe for the emergency services. We clear the carriageway of any debris and re-open the road.
"If there are injuries involved, it becomes a police-led incident. If it's a minor shunt with no injuries, we manage it ourselves."
The team's cars are fitted with everything from first aid materials, spades, and traffic cones to waterproof ponchos, blankets and flashing lights to put around an accident scene. They also carry a kit to clear up minor oil spills.
There is always a minimum of two crews – four officers in two cars – on patrol in the county, and generally three crews plus a supervisor.
And the officers do a six-week training course covering all aspects of the job, including first aid.
Mr Dent added: "We have a tremendous bunch of staff here, we are very fortunate to have a first-class team at Watford Gap out-station."