Sustrans policy advisor Matt Hemsley has spoken to ITV News about the effect 'transport poverty' could have on the Welsh economy.
It comes as Department for Transport figures reveal Wales is the worst-hit part of the UK for fare increases - while also seeing the biggest fall in passenger journeys.
Mr Hemsley told us: "Buses are really important, particularly for people on lower incomes; young people who are struggling with the costs of owning and running a car as the costs of insurance and fuel go up.
"This is a big problem for the economy and lots of people."
A charity that promotes walking, cycling and public transport says the new Active Travel Bill has the potential to be the "most effective public health initiative since the smoking ban."
Sustrans Cymru first suggested the new law in a petition to the Assembly six years ago.
It says that the networks of new routes created by the Bill will play a major role in persuading people out of their cars for shorter journeys but what is also needed are programs that will help people to take advantage of the routes.
The evidence shows that the easiest way for most people to get more exercise is to build it into their daily routine, but even though most everyday journeys are short, many of us still choose to take the car; in fact 20% of our car journeys are less than one mile.
The Active Travel Bill aims to get more people walking and cycling for short local trips as part of tackling the obesity epidemic and reducing congestion.