‘Threshold of enclosure’ created by vertical surfaces or series of vertical elements in an urban plaza, represented by the ratio of height and distance

Q. ‘Threshold of enclosure’ created by vertical surfaces or series of vertical elements in an urban plaza, represented by the ratio of height and distance, is given by an angle of _________degrees (rounded off to one decimal place).

A. 26.5°

B. 16.5°

C. 13.5°

D. None of the above

Ans: 26.5°

Correct Option: A

Explanation:

h/d ratio is 2 : 1 for the ‘Threshold of enclosure’,

Thus, tan θ =1/2 θ = 26.5°

Though as a thumb rule, one can remember a value of 27 to 30 deg vertical angle for threshold of enclosure, whereas angle for minimum enclosure is 18 deg, after which there is loss of enclosure.