On Thursday, planners at the Boston Metropolitan Planning Organization gave preliminary approval to fund a $15 million project that will extend a dedicated, center-running bus transitway from Jackson Square to Ruggles Station in Roxbury.

The project, which is still being designed but could begin construction within the next year, would extend and double the length of another dedicated bus transitway project that’s already under construction (pictured above) on Columbus Avenue between Franklin Park and Jackson Square.

The northern extension, which will continue north on Columbus Avenue and onto Tremont Street, is expected to benefit considerably more riders. While the under-construction segment south of Jackson Square carries three bus routes, the segment of Tremont Street between Ruggles and Malcolm X Boulevard carries six routes, including four of the most heavily-used, frequent-running bus lines in the MBTA system: the 15, the 22, the 23, and the 28.

Pre-pandemic, this segment of Tremont Street carried roughly 28,000 bus riders per day, making it the highest-ridership bus corridor in the city, according to Boston Transportation Department officials.

And during the pandemic, ridership on these routes has remained relatively high, compared to the rest of the MBTA system. While the typical bus route is carrying around 40 percent of its pre-pandemic traffic, ridership levels on the 22, 23, 15, and 28 are between 50 and 60 percent of their pre-pandemic volumes, according to the T’s most recent ridership data.

Tremont Street between Ruggles and Columbus Ave. has also been identified as one of the most congested bus corridors in Boston, according to a 2016 analysis of bus delays on the MBTA system:

On Wednesday morning, the Boston Region Metropolitan Planning Organization (MPO) gave its preliminary approval to allocate its federal highway funding to the $14.8 million project in its proposed Transportation Improvement Program budget.

The funding for the new busway became available after unexpected delays or cost savings associated with other federally-funded projects opened up an opportunity for the MPO to fund a new project that could be planned and built relatively quickly.

During Wednesday’s MPO meeting, Tom Kadzis, a Boston Transportation Department (BTD) planner, told other members of the MPO that the city has been able to build the current Columbus Avenue project very quickly and efficiently, and expressed confidence that the city and MBTA could deliver the new project within the next year.

“I don’t know if we’re going to get anything that would give us the bang for the buck that this project gives us,” said Kadzis.