LONDON, May 11 (Xinhua) -- Spectators planning to travel by train to Prince Harry and Meghan Markle's wedding in Windsor are being urged by a British railway company on Friday to start journeys as early as 4 a.m. (London time).

Britain's Great Western Railway (GWR) told passengers to "travel early and travel light" to reach the Berkshire town in time for the midday wedding.

GWR, which operates trains to the Berkshire town, published times for trains due to arrive in Slough at 8:00 a.m. or 9:00 a.m. (London time) for a connection to Windsor, leaving Preston at 4:15 a.m. and Stafford at 5:25 a.m. (London time).

Passengers have already bought train tickets to Windsor for May 19 from destinations across the UK, from as far away as Scotland and Devon.

A "sizeable queuing system" will be in place for the six-minute train from Slough to Windsor and Eton Central, which only accommodates a four-carriage train.

GWR managing director Mark Hopwood said, "We help thousands of people each year travel to some of the biggest events in the country: Reading Festival, Glastonbury, Henley Regatta and many more."

"This will be one of the largest ever one-day events that has taken place on our network and our aim is to ensure our customers have a great day out and enjoy what will be an international spectacle," he said.

About 2,300-meter-long fencing will be used for queues across the busiest stations on routes to Windsor.

Passengers travelling from the West, South Wales and the Cotswolds are advised to change at Reading for services to Slough.

Those travelling from the London area should use South Western Railway services from London Waterloo to Windsor and Eton Riverside.

Any latecomers may be forced to miss the procession as Thames Valley Police can order trains to not stop at Windsor and close off the route if the number of visitors proves to be a safety issue.

Police in March said they are expecting more than 100,000 people to visit Windsor for the wedding.

A 30-million-pound "ring of steel" will surround the wedding of British Prince Harry and Meghan Markle, including barriers, vehicle checks, snipers and airport-style scanners, at Windsor Castle in May.

The "ring of steel," which costs about 42.18 million U.S. dollars, will be erected to deter terrorist vehicle attacks, said Thames Valley Police, responsible for policing the event, adding that the operation is likely to be the biggest in its history as they gradually build up the security in the city over the next seven weeks.

It takes about 44 minutes to travel from London to Windsor Castle. Approximate driving distance between London and Windsor Castle is 37 kilometers.

Windsor Castle is a royal residence at Windsor in the English county of Berkshire. It is notable for its long association with the English and later British royal family and for its architecture.