The double-decker buses on London's streets are an iconic symbol of England. Now, New York City may be getting some of its own.

The MTA on Monday unveiled a double-decker bus that it will be trying out on an express bus route as part of a pilot program.

It's not the first time the city has seen double-decker buses on its streets. Here's some info about the double-decker's past and about the current fleet:

Double-decker buses ran on city streets from the 1930s through the 1970s - and then briefly again in 2008

A pilot program for double-decker buses 10 years ago ended in failure. New York City Transit President Andy Byford said the buses at that time were not equipped to handle the roads.

"My understanding was, where New York previously trialed double-deck, there were problems with the air conditioning, and the technology just really wasn't appropriate to handle New York streets," Byford said. "I'm convinced that now's the time to give double-decker a go again."

The double decker will be tested on the X17J express bus line

The X17J line is an express bus line that runs between Staten Island and Manhattan.

Byford said the double-decker buses are suited for express lines and not local lines because the express buses serve longer routes with fewer stops.

"You wouldn't deploy these on local routes, typically, because there is that extra time factor of people getting on and off," Byford said. "But for an express route, where there is that bit more time but you need the capacity and you want to give people a really comfortable ride on a long route, these vehicles, I think, are ideally suited. That's why we're doing the trial."

The double decker raises the capacity of an express bus by 42 percent

Byford said the new double-decker express buses will be able to seat 81 passengers. That's nearly double the capacity of a standard bus.

"It's perfectly suited to express routes, where dwell times - in other words, the time at the stop - isn't so critical. We've got plenty of time for people to get on and off in comfort," Byford said.  "Where we want to get people seated and we want to give people a comfortable ride over those longer distances, this vehicle's particularly suited."

The double-decker pilot is part of a wider bus improvement plan

The MTA unveiled a plan on Monday to overhaul a bus service that has seen average bus speeds slowing for years.

The double-decker buses are one part of the plan. The MTA also wants to give bus riders the ability to pay their fare before boarding - they hope to enable all bus riders to do that by 2020 - and to board at any door. 

The plan will also remap some bus routes and expand off-peak service, bus-only traffic lanes and routes that give buses priority at signals.