Chain measurements across rugged or hilly terrain have a permissible error limit of_____________?
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Answer: B. 1 in 250
Explanation
Chain measurements across rugged or hilly terrain have a permissible error limit of 1 in 250. Rough topography makes precise horizontal chaining difficult due to slope breaks and physical obstacles. Survey specifications relax allowable closure limits for difficult terrain compared to flat open ground. Chain surveying accuracy is expressed as a ratio of the misclosure error to the total measured distance. Hilly terrain requires breaking the chain, using plumb bobs, and applying rigorous slope corrections. Despite precautions, uneven ground introduces physical errors that justify a higher permissible limit.
Preliminary route surveys across mountainous country rely on chains where high-end EDMs are unavailable. Civil engineering contracts specify exact permissible error limits to determine acceptable survey quality. Exceeding the 1 in 250 limit forces field crews to rechain the section to ensure data reliability. Option 1 in 100 represents an excessively loose error limit that would result in unacceptable survey quality. Option 1 in 500 is specified for flat open country with ideal weather and chaining conditions. Option 1 in 1000 demands high-precision base measurements using steel tapes rather than standard chains.
- Subject
- Engineering
- Category
- Civil Engineering
- Topic
- —
- Difficulty
- medium
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