One-in-seven employees of companies awarded contracts to work on the railways failed random drugs tests in the last year.
The tests were carried out before any of the workers were let begin work on the lines at mandatory track safety courses run by Iarnród Éireann.
The State-owned rail operator uses contractors to carry out a range of different functions on its rail lines and infrastructure including track maintenance and other services.
Iarnród Éireann said it had now established a group to look at strengthening its policies in relation to drugs and alcohol.
Secure contracts
One option being examined is that all employees of companies who secure contracts with Iarnród Éireann to carry out work on the railways would in future have to undergo mandatory drugs and alcohol tests, not random ones.
Iarnród Éireann told Minister for Transport Shane Ross in August that the failure rate being recorded for contractors who tested for drugs or alcohol at pre-employment courses had "led to increased scrutiny of contractors".
The rail company already has a policy of testing 5 per cent of its own 3,700 staff for drugs or alcohol on a random basis each year.
It said that in the last year, three out of 121 of its own employees who underwent testing failed. A spokesman said that, in the year to early September, 10 out of 70 employees of contractors who were tested for drugs or alcohol failed.
