After a decade of delays, failures, and cost overruns, SEPTA’s Key smart fare system is about to hit another milestone: a price tag nearly double the original plan.

SEPTA recently agreed to pay Conduent Inc. about $29.5 million for two more years of operational and customer support for its Key card system. That will bring the cost of the project to $238 million — up from $122 million budgeted in 2011.

When the authority’s board last week approved the new payment, it was the 27th tweak to the Key card contract in the last 10 years. SEPTA insiders say it’s the largest number of such changes in recent memory.

The latest payment was needed because customer support systems, including call centers; equipment maintenance, repair and replacement; software maintenance; and wireless service for fare-card readers were no longer covered under the base contract with Conduent, SEPTA officials said.

“We need to make sure the system we have is running as well as it possibly can and that we are not falling behind,” chief spokesman Andrew Busch said.

» READ MORE: The cost of SEPTA’s Key card system just swelled to nearly $200 million — way more than planned

Key has suffered from delays and cost overruns since it was introduced in 2016 — two years later than scheduled. SEPTA has scrambled to order fixes to problems such as a confusing user interface in stations and on the web, as well as to keep pace with rapidly developing technology and evolving financial security standards for the cards.

At times the cards have been unreadable, particularly by the wireless readers aboard buses, which range more broadly than trains or trolleys and are more likely to encounter dead zones. An unknown number of passengers have been waved aboard for free rides during glitches over the years, costing SEPTA income.

Conduent, a global company headquartered in central New Jersey, was spun off in January 2017 from Xerox, which began working with SEPTA on the Key project when the original contract was signed in 2011. Conduent provides digital platforms for financial transactions between businesses and their customers, and provides systems to collect roadway tolls and transit fares to several hundred customers around the globe.

The company declined to comment Wednesday, referring questions about the project to SEPTA.

The cost of the Key system was set at $122 million in the first contract, and has grown in price since then as changes and adjustments were needed.

SEPTA is already soliciting ideas from automated fare-collection providers for the next generation of the system, which officials are calling Key 2.0. Busch, the agency spokesman, said SEPTA hopes to issue a formal request for bids on the project by the end of 2022.

Meanwhile, updates to Key continue. Under a previously approved spending increase, new electronic fare readers have been installed in 1,100 of SEPTA’s 1,400 buses, Busch said. The equipment will then be installed across the system.

Bus riders would be able to use smartphones to pay fares, either with ticket bar codes or credit apps in a pilot program, Busch said. Eventually fare readers across the transit network will accept smartphone payment.