Around 2,000 cash-in-transit journeys per year will no longer have an armed escort following the withdrawal of the security detail.
Gardaí and the Defence Forces used to provide a shadow patrol to protect millions of euro but the service has been removed in recent weeks.
It is understood the banks, which pay around €7m per year for the escort, decided the service was no longer needed due to new operational security
SIPTU, which represents some cash-in-transit workers, said it did raise concerns with the sector when this was first suggested.
Spokesperson John King said the union expects that the operational measures are as robust as can be and they were assured that the new measures were satisfactory.
Millions of euro is transported by cash-in-transit vans every day, operating from cash holding centres to the main banks and ATMs.
However the vehicles have been a target in recent decades with some high profile, violent robberies.
This led to an agreement in 2005 that banks would pay for an armed escort to accompany their workers as the cargo was transported.
The security detail usually involved at least eight armed soldiers as well as two gardaí.
A spokesperson for the Irish Bankers' Federation said security was a matter for the individual banks.
