The Fradley and Streethay public right of way on the A38 trunk road will be closed for the next four years while HS2 construction work takes place.
Residents say they have been left to negotiate an "uncontrolled and dangerous" foot crossing in order to get across the four lanes.
Lichfield MP Michael Fabricant said the move by HS2 was "wholly irresponsible" and called for a temporary footbridge to be built to enable safe crossings.
HS2 said changes to the line's design that will see it run under the A38 meant it had been impossible to keep the right of way open.
Phil Thornett, who lives in Streethay, near Lichfield, said the closure "severely impacts" safe access for residents to the countryside around the Coventry Canal.
He said: "The HS2 employees at the site were sympathetic, but when I enquired as to an alternative right of way or deviation, they directed my friend and I to an uncontrolled, poorly maintained and frankly dangerous foot crossing of the A38 – one of the busiest roads in the local area.
"A friend and I attempted the crossing as directed, but we were trapped for 15 minutes in the central reservation awaiting a small gap in traffic that we could dash through.
"It is incredibly unsafe, adds 2km to the journey and certainly does not serve as a fit diversion for the original."
Mr Fabricant, who has opposed the high speed line from its inception, said: "I have taken this up with HS2, as has Phil, asking whether a more suitable route can be devised and I have proposed a temporary footbridge constructed to avoid the need for pedestrians having to cross the busy four-lane A38.
"Phil is fit and well and able to dash across the A38 – others may not be able to do this so easily. In any event, it’s a highly dangerous manoeuvre for anyone with cars speeding along the dual carriageway.
"HS2 have a duty of care and providing a route which is poorly maintained and dangerous is not the answer and is wholly irresponsible.
"They cannot ask people to take their lives into their hands. This does not augur well for other work in the area."
An HS2 spokesperson said: "HS2 take our responsibilities to impacted communities very seriously and try to minimise disruption wherever possible.
"The footpath under the A38 will remain open, so that people can safely cross the road and there is still access to Hill Farm.
"However, unfortunately it has not been possible to find a way to keep the right of way open past the A38 during this phase of construction.
"After feedback from the local community in 2017, the railway in this location will run under the A38 rather than on a viaduct.
"This significantly reduces the visual impact of HS2 in this area, and the updated designs will now have sloping earth banks, improving the visual appearance and increasing the opportunity for landscape planting and wildlife habitats."