PART 2 : MAXIMUM SIZE ENVELOPES : ENVELOPES A AND B
Concept and Practical Determination of Envelopes A and B
Envelopes A and B are designed to facilitate the wartime planning and movement of flat wagons carrying military
vehicles and equipment classified as "exceptional transport". The envelopes allow maximum flexibility of movement on
European railway systems, because the gauges are generally greater than the PPI gauges.
General Characteristics of these Envelopes
Bearing in mind the current amount of military equipment to be transported, the Group of Experts on the
Transport of Out-of-Gauge Equipment considered two envelopes (Envelopes A and B).
Both having a vertical axis of symmetry.
Having the same contours in the upper portions (from 3.370 m above the rails).
One outside, and the other within the PPI gauge width.
The polygonal contours of the envelopes (in particular the portion above 3.370 m, which is identical for both)
were determined taking into account every possible route network and in such a way as to avoid any large-scale
operating constraints. These envelopes will be found in the attached Annexes B (Envelope A) and C (Envelope B).
Envelope B allows for a loading tolerance of ± 15 mm in width.
Establishment of Traffic Maps for Envelopes A and B on European Rail Systems
Envelopes A and B and their circulation conditions having been defined, each network will prepare circulation
boards for each line section showing the operating constraints on its lines.
By assembling these, each network will be able to prepare its own A and B envelope circulation maps.
To obtain overall maps of A and B envelope circulation on the networks mentioned in Para.1, by simply
juxtaposing the maps for each member country, it is essential that lines should be shown on the national maps on the
basis of the standard key described below:
Single track lines:
= Clear way or minor movement constraints (e.g. local reductions in speed).
= Circulation possible with certain major constraints (e.g. no circulation or shunting on a
= Circulation impossible.
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