"It's the backbone of the public transport network in Auckland and it's an incredibly important part of our plans to achieve mode shift."
In the last 12 months, there have been 21 million rail trips in Auckland. That compares to some 75 million bus trips over the same period.
But Young-Cooper told MPs the number of rail trips is expected to almost double to 40 million by 2028 after the much-anticipated City Rail Link is finished.
And rail, as a mode of public transport, has been getting more popular in recent years, according to AT data.
For example, the number of people using rail is increasing by six per cent a year.
The Government has a $6 billion rail spending package earmarked for the Auckland region over the next 10 years.
Young-Cooper said the extra Government funding will help build capacity as the popularity of rail increases.
"The rail network is absolutely critical to the future success of Auckland."
Since taking office in 2017, the Government has made rail a priority of its public transport spending scheme.
Deputy Prime Minister and Minister of State Owned Enterprises Winston Peters has said on multiple occasions that the Government was getting rail "back on track".
The Government allocated $1 billion to go towards rail in its infrastructure package, unveiled last month.
This comes after an extra $1 billion was earmarked for KiwiRail in the 2019 Budget.
In total, the Government has committed $4 billion to rail in New Zealand since it took office in 2017.