Knaresborough residents tweeted pictures of a gridlocked Knaresborough High Street on Monday, which marked the start of nine week roadworks at Bond End.
The junction is being completely redesigned to combat traffic congestion which has resulted in high levels of air pollution for more than a decade.
But since beginning the work the County Council has defended its efforts to control traffic, which were described as 'shocking' by one Twitter user.
A Spokesperson for NYCC said: "Bond End is a complex and very busy junction, but the County Council is committed to combating air quality problems there.
"As these junctions are very busy, the work will have an adverse impact on traffic flow at certain times and regular users are urged to bear this in mind when planning journeys and if possible seek alternative routes.
"The work was publicised well in advance, allowing drivers to avoid Bond End if they are able to do so.
"We hope users of the junction understand that we are acting on behalf of local residents who deserve to have a cleaner environment in which to live.
"Monitoring of traffic in the vicinity by highways staff on the first day of the work indicated that while there was some traffic build-up on High Street this was comparable to a typical Monday rush hour.
We are carefully monitoring the traffic movements and will adjust the traffic management as and when required, using manual control to replace timed controls when necessary, to minimise
disruption to road users during the works.
Up-to-date information on the progress of the work will be published at www.northyorks.gov.uk/bond-end-junction-improvements