A proposal to extend the pavement into Lewes High Street could bring traffic to a standstill, a town councillor said.
Lewes councillor Stephen Catlin (Independent) warned widening the pavement by the Post Office could make the High Street even narrower.
But East Sussex County Council said a consultation would be held with the town council and public.
Cllr Catlin said: “It is more than likely that we will see more traffic brought to a standstill in the future because it is difficult enough now for two-way traffic to pass freely when there are coaches unloading at the Castle and lorries unloading near the Post Office.”
The pavement could be widened to improve access for disabled passengers.
The county council is also installing real time bus information boards in Lewes including one outside the Post Office.
Cllr Catlin called for the town council and South Downs National Park to be consulted about the plans.
He suggested a park and ride facility to reduce congestion and proposed banning lorries delivering in the town centre between 10am and 4pm on weekdays.
Cllr Catlin added: “Traffic needs to flow through the High Street and while I whole-heartedly support any scheme to make boarding buses easier for the disabled, I do think there is a knock-on effect which may not have been considered.”
The bus information panels will be working by spring.
A county council spokesperson said: “We have completed preliminary designs on a separate proposal to improve access for disabled passengers by widening the pavement and building a ramp at the bus stop outside the Post Office.
“We have sought the opinions of local organisations including a small number of key stakeholders, to help us complete the preliminary designs. However, a full consultation will be held with all stakeholders – including the town council – and the wider public, when funding becomes available to progress to the detailed design stage.”