The most authoritative study on trail setbacks (trail distance from the tracks) and other issues is by Alta Planning. In general, 36′ is the minimum width to accommodate both train and trail. In the few cases where the corridor narrows to less than 36′ the trail is diverted onto city streets.
A survey of the 32-mile SCC coastal Branch Line by Mesiti Miller, a local civil engineering firm, determined that over 90% of the Santa Cruz Branch Line is wide enough to accommodate both rail and trail.
Source: Mesiti Miller Engineering
“Based on the above analysis, it is our opinion that building a 32 mile rails with trails facility on the UP Right of Way is feasable based on the width of the available corridor, excepting a few short segments diverted to public streets.” Mesiti Miller Engineering.