The Centre for Excellence in Universal Design is a group based in Ireland that was established by the National Disability Authority as a place to educate and raise awareness of universal design for an environment to be accessible, understood, and used by all people, regardless of size, age, or disability.
They have published a series of guides called "Building for Everyone: A Universal Design Approach." This series provides a comprehensive best practice guide for how to design, build, and manage spaces so they may be easily accessible for all people.
The first in the series, External Environment and Approach, focuses on pedestrian and vehicular environments and how they can be designed for the highest level of accessibility. Some of the major focuses are: topographical constraints, access routes, surface materials, street furniture, and signage. Click here for a free download of this guide.