Clearance Envelope

The clearance envelope is typically defined by the transit authority where the vehicles will be operated. In the case where the transit authority does not have a well-defined clearance envelope, general application envelopes exist from alternative standards. AREMA provides clearance envelopes for standard mainline railroad vehicles, and APTA has standard guidelines for preparing the clearance envelope based upon the wayside and vehicle criteria.

Standard: APTA RP-C&S-003-98 - Recommended Practice for Developing a Clearance Diagram for Passenger Equipment Purpose: This recommended practice provides a guide for passenger railroads to (1) determine their particular equipment clearance requirements and (2) develop a clearance diagram sufficiently specific to allow equipment designers to develop designs that will conform to those requirements. Criteria: Specify compliance with standard, also specify envelope requirements if any Usage: The contractor shall provide static and dynamic clearance outlines ..... per APTA RP-C&S-003-98, (example: to meet AREMA Plate-F, or Transit Authorities envelope)

Standard: AREMA - Chapter 28, Clearance Diagrams, Fixed Obstructions and Equipment Diagrams Purpose: This standard provides general outlines for both the wayside, and vehicle outlines for new construction, and reconstruction work. AREMA standards also provide data and calculation tables for clearance envelopes on non-tangent track. Criteria: Specify compliance with standard, state specific envelope required Usage: ... vehicle clearance per AREMA Plate-F.