Complaints about public transport staff have doubled as rolling rail shutdowns to build the state's major transport projects trigger a wave of commuter backlash.

Unprofessional conduct, customer service failings and poor responsiveness to complaints are fuelling the surge in frustration, according to the Public Transport Ombudsman, with public transport staff the top source of commuter complaints.

Complaints about drivers and customer service staff spiked from 886 last financial year to 2035 this year, the watchdog's latest annual report reveals.

Stranded commuters waiting for a replacement bus at Caulfied station. Credit:@TonyB_Melb, via Twitter

Dissatisfaction with public transport staff overtook service delivery as the top source of complaints this year. However, changes to the way the Ombudsman records staff complaints also played a key role.