Thousands of people are expected to travel to London this weekend to bid a final farewell to Queen Elizabeth II.
Roads, railways and even airports are expected to be extremely busy, as millions flock to the city in the coming days.
Across the South and South East, motorways such as the M3, M25, M23, M20 and M2 are expected to see disruption, meaning many will choose to travel to the capital by train.
The Rail Delivery Group, which represents rail companies in the UK, has warned passengers to expect busy trains to and from the capital.
Rail companies are urging passengers to plan ahead, as services on all routes will be extremely busy.
What advice have rail companies issued to passengers?
Great Western Railway, along with other train operators, Network Rail and Transport for London says it is working to provide as many seats and services as possible to enable people to travel.
The company said in a statement: "If you intend to travel, expect trains to be very busy, please do plan ahead and check before you travel. For the latest information on travelling to London visit the National Rail Enquiries website."
Other companies, such as South Western Railway and Southeastern have issued similar advice to passengers.
Will services to and from the capital be enhanced?
Chiltern Railways has told passengers it will be operating an "enhanced service" this weekend, which will allow more people to get to and from the city.
Other operators in the Meridian region have not clarified whether more trains will run over the coming days.
However, Southern Railway has said trains are expected to be 'extremely busy' and queuing systems will be in place in some stations, in a bid to cope with the soaring number of passengers.
In a statement Network Rail said: "London is going to be extremely busy as people come from all over the United Kingdom and abroad to pay their respects to Her Majesty. We encourage people to leave as much time as possible when making their journey and check before they travel."
Will my journey to London be affected by engineering work?
South Western Railway has suspended all planned daytime engineering works this weekend and is expected to issue a revised timetable this week.
They are warning people "to be prepared for very busy trains and stations, particularly in the Windsor area."
Engineering work which was set to close Oxford station has been suspended so people can travel by train to London to pay their respects to the Queen.
The station was due to be shut to passengers on Saturday and Sunday but it will now remain open, Great Western Railway (GWR) said.