Which of the following statement(s) is/are correct regarding selection of bridge site location? (i) Map study is used to identify the approximate location of the bridge site (ii) Reconnaissance survey is used for detailing the alignment and design (iii) Preliminary survey is used for rough identification of river bends (iv) Final location survey is used for the exact alignment and detailed design
- A(i) and (ii)
- B(i) and (iv)Correct
- C(ii) and (iii)
- D(iii) and (iv)
Solution
Concept
Engineering surveys for bridge site selection
Formula
NONE
Step-by-step solution
1. Map study is the desk examination of available topographic maps to identify tentative alternative bridge sites; statement (i) is correct. 2. Reconnaissance survey involves on-site inspection to assess terrain and discard unsuitable routes, not for detailed design; statement (ii) is incorrect. 3. Preliminary survey involves detailed instrument surveys and data gathering, while general river characteristics are noted during reconnaissance; statement (iii) is incorrect. 4. Final location survey pegs out the chosen centerline and provides data for structural detailing and working drawings; statement (iv) is correct. 5. Therefore, statements (i) and (iv) are correct. Answer: B
Explanation
In bridge site selection and engineering surveys: (i) Map study identifies approximate site locations using toposheets. (ii) Reconnaissance survey physically examines terrain and river features to eliminate unsuitable sites (not for detailed design). (iii) Preliminary survey collects detailed hydrological and topographic data. (iv) Final location survey establishes the exact alignment and gathers data for detailed structural design.
Why the other options are wrong
A) Incorrect because reconnaissance survey is for preliminary reconnaissance, not detailed design. C) Incorrect because both statements (ii) and (iii) mischaracterize the respective survey phases. D) Incorrect because statement (iii) is false.
Shortcut
Map Study = Approximate location; Final Survey = Exact alignment & detailed design.
Common mistake
Confusing the scopes of reconnaissance survey (rough visual inspection) with detailed survey.
Correct answer: B) (i) and (iv)