"It is the highest honour in a lifetime for every traffic police officer to ensure smooth and safe road flow for royal guests who have come to congratulate the King," Metropolitan police commissioner Lt-General Wiroj Chantarangsri said.

Wiroj also warned Bangkok motorists to avoid routes designated for royal and state events from today to Tuesday. He advised city residents to travel on public transport.

Before leaving, motorists should check what routes to use by calling the hotline number 1197 or visiting the website www.trafficpolice.go.th.

Many royal dignitaries will arrive today. Roads and expressways linking Bangkok International Airport and city-centre hotels will be closed at several sections for the passing of motorcades.

From 1pm tomorrow roads and expressways will be closed to traffic between city-centre hotels, the Ananta Samakhom Throne Hall and the Royal Naval Institute for most of the afternoon and evening.

The afternoon's road closures include routes connecting city-centre hotels to Surawong, Silom and Ploenchit expressways and those connecting the Yommarat expressway to the throne hall, the venue for the tribute ceremony.

In the evening, main roads linking the Royal Naval Institute with key expressways will be closed. These include Phitsanulok, Rajdamnoen Nok, Rajdamnoen Klang, Arun Amarin and Pinklao Bridge.

Parking is banned tomorrow on roads near and around the throne hall and the Royal Plaza.

Trucks will be banned from roads near the Royal Naval Institute from 2pm to midnight.

From 3pm until the end of the Royal Barge Procession parking is banned on four main roads along the banks of the Chao Phya: Maharaj, Phra Chan, Na Phra Lan and Thai Wang.