Motorists in London are being advised to allow extra time for their journey to work this morning as the Olympic route network comes into force across the capital.
Thirty miles of games lanes come into operation and "ordinary" motorists caught using them will face fines of £130, while release fees for impounded vehicles could be £200.
The games lanes run alongside existing lanes in London and will be used by authorised "Olympic Family" vehicles.
These include vehicles used by athletes, Olympic officials and VIPs with the lanes coming into force at 6am today, with 1,300 vehicles an hour expected to use them.
Most lanes will stay in place from 6am to midnight on each day up to Tuesday August 14 and will form part of a 109-mile Olympic Route Network (ORN) around London.
In recent days, teams of engineers have been working to put up signs and change some road layouts in preparation for the implementation of the ORN and the lanes.
During the period of the lanes being operational, some turns have been banned, some bus lanes suspended, some bus and coach stops have been adjusted and some pedestrian crossings will not be operational.
In addition to central London, there will be road restrictions around the sailing venues at Weymouth and Portland in Dorset, around the rowing at Eton Dorney in Berkshire and around the mountain biking venue at Hadleigh Farm in Essex.
Also, some roads will be closed for the men's and women's Marathons and the biking events.
Games lanes will generally be on the off-side (outside) lane. Cyclists will be able to use the near-side (kerbside) games lanes but not the off-side ones, while motorcyclists will be able to use some of the near-side lanes.
But taxis and private hire vehicles will not be able to use the lanes, nor will buses be allowed in most lanes. The games lanes will also be out of bounds to disabled drivers who are Blue Badge holders.
Taxi drivers took to Tower Bridge on Monday to protest against their exclusion from the lanes and more protests are planned across London today.
Transport for London (TfL) is urging drivers to avoid London from now until the end of the Games.
London mayor Boris Johnson said: "With just days until the opening ceremony, London is more prepared for the Games than any other Olympic city has ever been.
"The ORN is a requirement of all host cities, ensuring athletes and officials get to their events on time."