The MBTA’s long-awaited fare collection overhaul will not roll out over the next two years as originally planned, and officials will instead pursue a “reset” that will phase in the new system across the next four years and push the total project costs above $900 million.

The original $723 million contract with Cubic called for many of the features to come on line in 2020 in a so-called “big bang” and for all-door boarding to begin in 2021, but MBTA officials said a combination of technical challenges, public desire for input, and growing scope prompted a re-evaluation.

Some of the more dramatic changes coming in the automated fare collection 2.0 system, such as capability for passengers to tap a credit card at a fare gate or use all doors to board buses, now will not be piloted until three or four years down the roads.

MBTA officials declined to describe the new timeline as a delay, arguing that the change will allow rider feedback to play a bigger role and that milestones that are spread out will cause smoother implementation.

“We had structured a contract in such a way that made some assumptions about our partner and about our own capabilities and about what the community wanted,” MBTA General Manager Steve Poftak told reporters last Friday. “I think at the end of the day, all three of those assumptions were off, and what we’ve done here is a course correction.”

The updated plan carries more than $200 million in additional costs, including $160 million in new capital, more than $40 million on upgrading the existing system in the short term, and tens of millions in operations and maintenance.

Project leaders will present their intentions to the T’s oversight board this week and request a “downpayment” of $30 million toward the eventual restructured contract with Cubic as parties renegotiate.

As part of the adjustment, T officials will seek a separate $49 million contract with Scheidt and Bachmann to install new fare vending machines, enhance the existing CharlieTicket system to allow single taps to board and more, all of which is designed as a bridge to transition to the final automated fare collection system.

“It’s a phased rollout,” said Ronald Renaud, the T’s chief transformation officer. “That, I think, is the difference between failure and success. It’s an achievable schedule. Because of the extra two years, we have more time to test, listen, and then evaluate other technology.”

The first pilots for the new payment methods are now scheduled to start in 2021 and expand in the two subsequent years under the remodeled plan. Passengers will be able to use cellphones, contactless credit cards, and more to tap through fare gates, and they will also be able to use a website and mobile app to keep track of balances, according to plans.

All-door boarding on buses and above-ground Green Line stations, which T officials say will help speed up the rides and improve performance, will now be tested on bus and subway in 2022 and 2023. Final rollout to commuter rail trains is planned for 2024.

As part of the short-term improvements, the T will add more than 1,000 points of sale to acquire CharlieCards across the greater Boston region. Paper CharlieTickets will begin charging the same fare as plastic CharlieCards in 2021, according to the T, and passengers will be able to tap them to get through fare gates rather than inserting and scanning them.

CharlieCards themselves will incur a still-undetermined cost to acquire starting around 2023. They will allow commuters to run a negative balance on their accounts, meaning those who have insufficient fare on a CharlieCard can still board and pay back the deficiency rather than need to enter cash or wait until the next train or bus arrives.