Traffic on Union street in downtown Vineyard Haven will be reversed for one month beginning Sept. 13 and running through Columbus Day weekend. The change means that traffic on the one-way street that now leads from Main street toward Water street and the Steamship Authority will instead run up from the harbor to Main street.

A traffic committee advised the experimental reversal to see if it improves traffic flow in the downtown Vineyard Haven area.

“This is not a new idea, it’s one that has been discussed on and off for at least five years,” said selectman Tristan Israel, who served on the traffic committee. He said Union street used to be a two-way street around 15 years ago.

During the one-month trial period, cars (not trucks) coming off the boats will have a choice between turning left into the Five Corners intersection or taking a quick right and then left to drive up Union street and into Main street. The town hopes this will alleviate congestion at the busy Five Corners intersection.

Temporary signs will be placed around the area, and announcements will be made on the ferries. Extra police will be on duty in the area to assist, police chief Daniel T. Hanavan told the selectmen at their meeting Tuesday.

“I think it will give us some indication of pluses and minuses of reversing the street,” said town administrator John (Jay) Grande. He said since the experiment will not be held in the height of the season, he would caution against making any concrete decisions based on the results. Instead, he will recommend doing another experiment during period of heavier traffic, or doing an engineered model.

Mr. Grande said the Steamship Authority reviewed the plans and saw no negative impacts on their operations.

The selectmen voted to request that the Martha’s Vineyard Commission place counters at the intersection of Five Corners and on Union street during the experiment.

Late Sunday evening, after the last boat, signs went up.