"The signs should be down by Tayforth Rd to warn them. I don't know why they are coming this way. They should be directing traffic down Springvale Rd to London St."
Whanganui District Council has installed a series of temporary signs about the detour.
There is a sign on SH3 before Montgomery Rd advising truck drivers to detour via SH3 and Heads Rd. Further signs are positioned along Montgomery Rd and before the Tayforth Rd intersection.
The detour for northbound trucks travelling from Castlecliff is via Puriri St and Alma Rd to SH3.
A Whanganui District Council spokeswoman said the closure was signposted at every intersection on Mosston Rd.
All carriers had been notified through trucking bodies such as Heavy Haulage and NZ Transport Agency, she said.
On Thursday afternoon the council's infrastructure team confirmed that all the signs on the route had been correctly placed but it was decided to put up some additional signs.
In addition to the heavy traffic detour, until December 31 there is access for residents only to the section of Mosston Rd between Ruapehu St and Titoki St.
Kowhai St is closed at the Mosston Rd end with access for residents from Miro St.