Here is a table of the estimated required skill to plan bridges (by length and material). The person holding the dioptra requires this skill. These numbers are rough, whole-number estimates. '''You may require slightly more skill in practice.'''
<div style="overflow-x: scroll">{| class="wikitable"
|+Required skill by length (tiles) and material
|-
|-
|}
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Note to build any bridge section, the skill requirement is: