PORTLAND, Ore. (KOIN) — Changes have been made to some TriMet bus lines while the transit agency works to improve service amid the biggest operator shortage in its history.

In a press release sent Wednesday titled “We’re sorry,” TriMet apologized for continued bus cancellations despite having already reduced service earlier in the year. Now, the agency says its “severe” staffing shortfall is affecting MAX lines and trains are getting canceled, too.

“We hate to see this as much as you hate not seeing your bus or train arrive,” TriMet said in the release. “We’re working hard to restore the service you need and deserve, but we really need your help.”

To combat the shortage, TriMet is hosting a hiring event from 10 a.m. to 3 p.m. Tuesday at the Courtyard by Marriott near the Convention Center. The agency also increased its hiring bonus to $7,500 for new bus drivers with a starting pay of $25.24 per hour. Job seekers can apply online.

Beginning Sunday, bus lines 4, 21, 33, 57, 62, 75 and 82 are all seeing changes to their schedules as part of TriMet’s summer service improvements.

Among other major adjustments were on Line 15 trips to the Gateway Transit Center, which will no longer make stops from Southwest 18th Avenue and Morrison Street to SW 2nd and Alder Street.

TriMet is also slated to open its first Frequent Express bus line in just over four months, which transit officials say will be faster and have a higher capacity per bus.

In total, 10 bus lines are seeing alterations made to their schedules. For the new routes, stops and a full list of schedule revisions, visit TriMet’s website.