There are new calls for a wide ranging upgrade of Wales's railways, including faster trains, better stations, new carriages and urban light rail systems.
The assembly's enterprise and learning committee says it believes Wales is not getting its fair share of investment and needs to meet a rise in demand.
It said it was concerned passenger satisfaction with stations in Wales was much lower than other parts of the UK.
The Welsh Assembly Government will study the report before responding.
Official forecasts suggest substantial growth in rail use for both passengers and freight in the coming years.
To meet this demand, the committee makes a number of recommendations.
It said new high speed links are as important to Wales as other areas of the UK, and that both north-south and east-west links need improvement.
Urban light rail systems were also called for, for Cardiff, Newport and Swansea.
The AMs said they were worried to hear that passenger satisfaction with stations in Wales was much lower than the UK average, and want to see immediate action.
Karen Beattie, from Prestatyn, Denbighshire, who campaigns for better access to the rail network for people with disabilities, said there was a desperate need for improvement.
She said: "As I wheelchair user I have to phone up and give 48 hours notice that we going to be using the rail service.
"The railway station here is inaccessible unless you can use steps and we are in place where there is a Pontin's [holiday park] so the town relies on tourism."
Ms Beatttie said last year one visitor became trapped on the station not realising that she would encounter problems and had to call the emergency services.
She said an identical situation arose in Rhyl, when the station was only accessible by lift during manned hours.
"Information on the website is not always up to date if a station is accessible," she added.
Another proposal is to examine the potential for new light railway systems in urban centres such as Cardiff, Swansea and Newport.
But underlying the report is a concern that Wales is losing out on investment, and the AMs say the assembly government should gain much greater powers over the railways, akin to those held in Scotland.
Committee chairman Gareth Jones said: "This report examines the long-term future of the rail network in Wales.
"The evidence we have gathered indicates that freight and passenger traffic on our network will increase over the coming years.
"The objective hopefully will be that Wales benefits from this extra traffic so that we are better placed in terms of high speed link connections with the rest of the UK and Europe.
"It is important that the Welsh government provides for that extra demand.
"The Welsh government also needs to work with partners to improve the rail links and services between north and south Wales and to make stations fully accessible to all passengers."
The assembly government said it would study the report and respond in due course.