Bridj has expanded into the South End and rolled out additional changes to its service in and out of South Boston. To “celebrate the arrival of Spring and death of Winter,” says Ryan Kelly, the company’s marketing manager, Bridj is making “most rides only a $1” for the rest of April, “with only a few select peak morning trips at $3.”

Bridj buses started providing trips from the South End to Downtown Crossing, the Financial District and the Seaport on Monday, the company announced in a blog post. Additionally, Southie residents are now afforded trips to Copley Square and Prudential.

“This is a three week pop-up trial that will allow our research team to test our predictions about connecting these vibrant parts of our city,” Bridj states in its blog post. “If you and your neighbors ride as much as we’ve predicted, we’ll make this a long term fixture in our service area.”

Bridj says “tens of thousands of request” for new routes outside its current service area have poured in over the last few months, “and we’re working hard on fulfilling them as efficiently as possible.”

To reserve a seat, riders can use the code “popup” and receive their first three rides free. The code also applies to Bridj’s Spring promo, which allows riders to book “most other rides” for $1.

In February, Bridj announced plans to launch in Washington D.C. Before that, in January, a source told BostInno that Bridj was in the process of raising $10 to $15 million in Series A funding – a round expected to value the company at $60 million.