The consultation on the various options runs until 24 November
Businesses and residents in the Powys town of Newtown are being asked for their views on plans for a bypass.
Six options are being put forward by Transport Minister Ieuan Wyn Jones for public consultation.
There have been calls for a bypass to solve Newtown's congestion problems for more than 30 years.
An exhibition will be held at the Monty Club between Tuesday and Thursday and a brochure and response form will be sent to residents and businesses.
The consultation, which starts on Thursday, runs until 24 November.
It also involves a series of other transport improvements aimed at relieving congestion and improving safety.
These include improved access from New Road to the railway station, a combined footpath and cycleway crossing the Cambrian Railway and another crossing the River Severn.
"The residents and businesses of Newtown have suffered the effects of congestion for a number of years and if we don't act to improve this situation it will only get worse," said Mr Jones.
"These proposals will not only bring safety and environmental benefits to the residents but will also help further the economic development of the town.
"Newtown is situated on the very important north to south and east to west corridors of the A483 and A489 so this bypass is also of vital importance to the whole of Wales.
"It will improve journey times and reduce accidents on these routes."
Work on investigating a bypass of Newtown dates back to 1969.
In 2007 Parsons Brinckerhoff were appointed as consultants to carry out a study to consider on the options available which will be the subject of the public consultation.