The works have required the introduction of a number of temporary traffic management measures on roads in the surrounding area and on the A66 itself.
A spokesman for Middlesbrough Council said: "The works are progressing well, and we would like to thank residents, businesses and motorists for their patience while they are underway.
"We would also like to remind everyone that all of the businesses in the surrounding industrial estates remain open as usual and are fully accessible to the public."
The A66 is the busiest east-west route in Middlesbrough, carrying between 50,000 and 90,000 vehicles on a typical weekday, over 10% of which are HGVs.
As well as serving the town centre, the A66 plays a key strategic role in connecting the A19 and A1(M) Trunk Roads to the west with Teesport and the South Tees Development Corporation site to the east.
A171 Cargo Fleet Lane is one of the Borough's busiest north-south routes, serving east Middlesbrough and linking the town centre with Guisborough, Whitby and Scarborough.
The A66/A171 Cargo Fleet junction carries around 5,000 vehicles per hour during the morning and evening peak periods, and operates close to its practical capacity at such times.
This frequently results in delays and congestion, increasing journey times and reducing journey time reliability on two of the Borough's most important roads.
The introduction of a signalised crossroads at the Cargo Fleet Lane/South Bank Road junction will ensure that the two junctions operate together as efficiently as possible.
Just as importantly, it will allow signal-controlled pedestrian and cycle crossing facilities to be introduced, providing a safe and direct route for users of Route 1 of the National Cycle Network - which runs along South Bank Road - and, by doing so, improving cycle connectivity between Middlesbrough and Redcar & Cleveland.
Works to construct the scheme commenced in October 2019, and completion is programmed for late spring 2020.