Liz O’Donnell also expressed concern a fall in detections for road safety offences last year could be due to lower garda numbers.
A total of 195 lives were lost on Irish roads in 2014 — a 4% increase and the second year in a row in which the annual road fatality figure rose.
Ireland is rated as the 8th best road safety record in the EU.
In her first annual report as RSA chief, Ms O’Donnell said one of the positive results from last year’s “grim and disappointing” statistics was a reduction in driver deaths, particularly among young adults which, she said, may be due to the measures introduced as part of the Graduated Licensing System.
However, commenting on the country’s road safety performance, she warned about the increased danger posed by motorists who allow themselves to be distracted while driving.
“I truly believe this problem is getting worse, particularly the issue of distraction by mobile phones which for some borders on addiction.”
She pointed out the RSA’s own research showed one in 12 drivers use a phone while driving.
A decline, she said, in detections across all the main road safety offences in 2014 might signal greater compliance with road traffic legislation by motorists. However, it could also be due to a reduction in the size of the Garda Traffic Corps from 1,200 in 2009 to approximately 750 last year which, if true, would be “of great concern”.
“A highly visible presence of gardaí on the road, plus the threat of enforcement, is the single biggest factor in changing people’s behaviour on the road,” said Ms O’Donnell.
It also emerged that 5,000 vans and lorries were found to have highly dangerous defects during routine testing last year.
The RSA said it was concerned at the large number of defective commercial vehicles discovered during applications for a certificate of roadworthiness, especially as the majority of problems related to brakes.
It said it was also a matter of concern that separate roadside checks had identified 191 vehicles which were so dangerously defective that they warranted immediate action such as impoundment or repair on site.
In all, the RSA’s annual report for 2014 showed 8,226 vans and trucks or 44% of the total stopped at roadside checks last year had defects.
In addition the RSA said 7% of heavy commercial vehicles were not displaying a valid disc for a Certificate of Roadworthiness when stopped. Similar tests showed that 48% of school buses had some type of defect when inspected last year with 17% defined as having major defects.