Bangkok's legendary traffic jams might decrease with Thailand's royal family distributing a handbook of guidelines for motorcades and other public appearances to police and other authorities. 

It covers the practices that irritate the public in a country where open criticism of the royal family is not just illegal, but punishable by up to 15 years in prison. The palace hopes the changes will end the age-old notorious traffic congestion in the capital of more than 12 million people.

"Every time there's a traffic jam, everyone wonders if there's a royal motorcade passing by," palace official Chantanee Thanarak told a police training session at national police headquarters in Bangkok. "The royal family never meant to bother the public."

About a dozen members of Thailand's huge royal family travel by motorcade, including 84-year-old King Bhumibol Adulyadej, the queen, their children and grandchildren.

Until now, police stopped traffic in both directions and over many blocks far in advance of a royal motorcade. Traffic was also halted on highway overpasses. This was not just a security concern, but also protocol to establish that no head would be higher than a royal's.

The measures spoil traffic and calls for extensive police presence. This has been secretly criticized as excessive.

The new guidelines claim to allow traffic on overpasses and oncoming traffic on the road opposite a royal motorcade. The halts also will be briefer and fewer police will be used for royal road closures.

Besides, a new rule has been added that do not shoo away mall hoppers when a royal family member appears in the mall. "But be careful not to let people get close to royal family members," the manual says in a statement.

The new procedures will be effective immediately and police are being trained on them. The 48-page handbook has photographs of how to close roads and manage crowds and includes palace phone numbers that authorities can call in case of any doubt or confusion.