The transport operator cited challenges in driver recruitment, driver unavailability and contractors for the service cancellations.
Bus Éireann has issued a statement following a number of cancellations to services on Sunday (24 July).
The transport operator cancelled dozens of services on Sunday, in particularly in the north-west of the country.
"Most service disruptions today have occurred in the north-west, on the Sligo town service and some stagecarriage routes in Mayo/Galway," Bus Éireann said.
"There is more minor disruption in Waterford where the W4 city services will operate at reduced frequency for three and half hours in the morning, between 9am and 12.30pm. The W5 city service will operate at reduced frequency for two hours in the afternoon, between 2.15pm and 4.15pm."
A number of Expressway inter-regional services were cancelled as well, including round trips between Wexford/Dublin, New Ross/Dublin, Tralee/Waterford, and a single trip from Dublin to Ballina.
"We understand and regret the impact of cancellations on customers," Bus Éireann said.
"In most cases, advance notice of cancellations is available the day before. For people who have pre-booked their Expressway tickets, they are also notified by a direct email sent to them, typically well in advance of travel, allowing them to make alternative arrangements and transferring to other services operating either side of their intended departure.
"We very much encourage customers to book ahead at
expressway.ie to benefit from a guaranteed seat and priority boarding.
"Typically, service issues arise from a number of factors depending on location. This can include challenges in driver recruitment, driver unavailability often at short notice and more recently difficulty in hiring contractors to support services. This has more impact at comparatively smaller depots.
"Bus Éireann is actively recruiting for drivers throughout the country, and in Cork and Limerick has started to train people with Category B driving licences to gain their Category D driving licence.
"Where it unfortunately necessary to cancel a service, we manage this to minimise the impact on customers, for example temporarily reducing frequency on higher frequency routes and making every effort to ensure the last service of the day operates."
