The new £ 20 billion railway was seen as a change in travel patterns around the capital, reducing travel time and providing much-needed network capacity as a whole.
But despite the underground traffic on the central part of the route, it is not considered a new metro line.
Why is the Elizabeth Line not considered the London Underground line?
There are two main reasons TfL does not consider the Elizabeth Line an addition to the Tube network.
First, the line runs through much of the national rail network, using the infrastructure of the Greater East and Greater West.
Second, TfL officials say, is that trains are just much bigger than trains on subway lines.
Trains on the Elizabeth Line carry about 1,500 people each, compared to about a thousand on the Central Line.
At a media briefing in March CrossroadsCEO Mark Wilde said the Elizabeth line was not a “subway line” but was in fact a “new mode of transportation”.
He said, “[It’s] a bit like you would have RER in Paris or S-Bahn in Munich.
“Big trains from Heathrow, from Reading, will arrive right in the tunnel, through the central area and on the other side to Shanfield. There was nothing like it in the UK. “
However, the debate is likely to continue among Londoners.
Passengers will be able to travel by subway or DLR at nine of the 10 new Crossrail stations, although Bond Street will not open earlier this year.
Fare rates will also reflect subway fares other than trips to and from Heathrow, although the price limit will limit how much customers can pay.
On Thursday, TfL released an updated Tube map, of the Crossrail is shown as a white line with a double purple border rather than solid lines of tubular lines.
“The Elizabeth Line itself is the full name of the new railway and the route it operates,” the spokesman said.
“In contrast, the London Underground is the name of a separate mode of transport that operates on individually named routes.”
The line stretches from Reading in Berkshire and Heathrow Airport in west London to Shanfield in Essex and Abby Wood in south-east London.
Initially, it will operate as three separate railways, and by May 2023, all sections will be fully connected.