Mechanics facing eviction from their garage, which is situated on land earmarked for the Watford health campus, plan to move their business to a barn in Aldenham's Green Belt.
Proposals have been recommended for approval to allow The Mill, in Blackbirds Farm, Blackbirds Lane, to be converted from an agricultural building into a vehicle repair shop.
Applicant Commercial Motors is a tenant of Cardiff Road Industrial Estate, located behind Watford General Hospital.
The business has been a tenant in Watford for more than 45 years but has to be relocated to make way for the Watford health campus scheme, which will cover a 29 hectare site.
The scheme, which is a joint partnership between West Hertfordshire Hospitals Trust, Watford Borough Council and Watford Football Club, looks to expand hospital facilities and built about 750 new homes and retail space.
Watford Borough Council planning officers have recommended the scheme for approval at tonight's planning meeting.
In a report submitted to Hertsmere’s planning committee, officers said Commercial Motors looked for an alternative site for the past 18 months, but nothing suitable was found.
The report said: "No other site has been identified which viably meets the business needs and would allow them to relocate and retain their presence within the wider area."
It added: "Watford and their yard and premises have always been kept clean and tidy and they are timely rent payers. There have been no environmental or health and safety issues reported to the council in that time."
However, residents objected to the proposals as the land is located within the Green Belt, making it an "inappropriate" development.
Aldenham Parish Council stated: "The application site is totally unsuitable for the business use that is proposed as it involves the repair of large vehicles.
"This type of business activity would be more appropriately suited to an industrial area rather than this rural location."
Concerns were also raised about the effect the increase in traffic would have on those living nearby.
The Radlett Society and Green Belt Association said: "Overall, we have real concerns about the change of use that's the key part of this application.
"While other agricultural locations found locally do vehicle maintenance work, this is mostly for cars and small vans.
"The arrival of buses, coaches and lorries up to 24 tonnes could have a detrimental impact on the safety of and damage to surrounding highways and verges, factors which were cited as reasons for dismissing an appeal in 2008 against the use of the site for re-processing bread. HGVs would bring additional noise and fumes to what should be a quite, rural location."
Council officers recommended politicians approve the application "in light of the very special circumstances provided".
Plans are due to be discussed at tonight's Hertsmere Borough Council planning meeting.