Residents are unhappy over bus drivers using a dead-end road near their homes as a 'non-authorised bus depot'.
Up to three buses are reportedly seen at a time parked up at the end of Charlton Road in Brentry by nearby homeowners from as early as 6am.
Residents claim the double-decker buses are sometimes parked up against gardens and engines left on as drivers appear to be taking a break.
The road is served by First Bus's 2a route, which started in August and goes from the city centre to Charlton Road where it terminates.
One person, who did not wish to be named, said: "The company is using the roads as a non-authorised bus depot out of their routes.
"These buses shouldn't be here and now we have one bus coming every five minutes, and two to three buses at a time."
Emma Chappell, aged 34, has complained to the bus company.
She said: "If the bus came here and turned around I wouldn't have a problem, but they don't.
"They stop, more than one at a time, the drivers get out, have a chat and then you hear the air brakes go on and off. It is really inconsiderate and disruptive.
"Sometimes the buses will even block the road."
She added: "Some kind of consultation with us before this happened would have been nice."
In response, Chris Hanson, head of operations at First West of England, apologised to any residents suffering disruption.
He said: “Firstly, we apologise for any disruption our vehicles have been causing to local residents.
"Charlton Road is the terminus for buses on the 2a service which started operating in August.
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"As this is the end of the route there are occasions where buses will wait a short time at this location before departing on their next journey. This is no more than between 10 and 15 minutes at an absolute maximum."
He added: "Many of our vehicles automatically cut out when they are stationary.
"However, if a driver has a vehicle that does not have this facility they are instructed that they should turn the engine off if sitting for more than a minute and we will be reminding all our drivers of this policy in light of this complaint.”
