Is there a way to replicate the Travis CI build environment?

I’m trying to contribute to several open source projects, but I’m unable to get them working on my local machine. Fortunately, these open source projects use Travis CI. Unfortunately, I don’t know how to replicate the Travis CI environment on my local machine, even with the use of Docker images I’ve created myself, which don’t really replicate the setup.

Are the Docker images used by Travis CI publicly available?