Motorists can expect long delays in Stroud as traffic chaos unfolds.
Three-way traffic lights are in place with one lane closed on the A46 Bath Road in Stroud, between Rodborough Hill and the Kwik Fit garage.
The work to remove Ash Dieback trees is expected to be completed on Wednesday.
To compensate for the loss, two trees will be planted for every one removed, as part of upcoming planting schemes at the site and in Cainscross.
Following the work to remove the trees, further works will be undertaken to improve the streetlighting and cycleway at a later date.
Cllr David Gray, cabinet member for environment and planning, said: “We never want to lose any trees, but here it is necessary to make improvements to the cycleway. We have explored all options to see if they could be retained but unfortunately that wasn’t viable in this case.
“We will be replanting two trees for every one lost to compensate for this loss. We are committed to creating a greener Gloucestershire and tree planting is an important part of doing this, as they help to tackle climate change and support biodiversity.”
The improvements will remove barriers to existing cycle and pedestrian journeys, by updating the existing infrastructure to the latest cycle design guidance, with raised crossings of the side roads and setting the street lighting to back of footway.
