Rather than post John Wetmore's slides, he has asked me to provide a list of web resources which may be more educational. Please choose from the links below:

When are pedestrian bridges necessary, and when do pedestrian bridges work?

Why should there be a planting strip between the curb and the sidewalk?

The Three Things Pedestrians Need, a 53 minute video:
(This video contains most of hte slides used in his powerpoint.