Set-back distance in highway planning In highway alignment and roadside control, the set-back distance is defined as the horizontal distance between which two reference lines?

Introduction / Context:
The concept of building line, control line, and set-back distance is fundamental to highway right-of-way management. It governs where permanent structures may be built so that future widening, safety clearances, sight distance, and access control can be maintained.

Given Data / Assumptions:

• Highway corridor has two regulatory lines: building line and control line.
• Road land boundary separates right-of-way from adjacent private land.
• Set-back distance is a planning control used by highway authorities.

Concept / Approach:
The building line is the nearest line from the roadway within which permanent buildings are not permitted. The control line is farther away, controlling certain types of development/activities. The set-back distance is the spacing between the control line and the building line, i.e., the additional margin that further regulates development.

Step-by-Step Solution:

Verification / Alternative check:
Highway geometric design and roadside development control manuals describe set-back as a policy spacing between the building and control lines to reserve space for future needs and to protect safety and aesthetics.

Why Other Options Are Wrong:
Options involving the road land boundary confuse right-of-way with development control limits; set-back is not measured from the road land boundary.

Common Pitfalls:
Mistaking right-of-way width for set-back; ignoring local by-laws which may prescribe different absolute distances but preserve the same definition.

Final Answer:
Building line and control line