Atlantic Cities: The Commuting Penalty of Being Poor and Black in Chicago

I've actually been wanting to share this article since it was only discovered recently. Here's a takeaway:

In this way, the spatial mismatch between jobs and housing is as much an issue of transportation as of segregation or economic development. [Virginia Parks, an urban geographer at the University of Chicago] is agnostic on the policy solution implied by that: The city could work to create more jobs in black communities. But it could also improve transportation out of those communities to job centers that already exist.

What's not entirely clear to me is whether or not commuting is about driving or public transportation - that is by train or bus.