--- title: "Updating information across survey stages" subject: "Transportation Engineering I" chapter: 2 key: "semester_6/transportation_engineering_i:info-updated-stages" source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/info-updated-stages site: BCT Engineering --- # Updating information across survey stages Transportation Engineering I · Chapter 2: Highway Alignment and Engineering Survey - Asked in: 2078 Chaitra, 6 marks; 2073 Magh; 2068 Magh (old course) (asked 3 times) - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/info-updated-stages - Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-2 ## Question Explain how the information collected in the preceding stages of survey is updated/utilised in the succeeding stages of highway alignment (road alignment) survey. ## Short answer Data from each stage is verified and refined in the next: map-study routes are field-checked during reconnaissance; reconnaissance notes are precisely measured in the preliminary survey; the preliminary plan guides final centre-line setting with adjustments for earthwork and structures. Estimates evolve from rough to detailed. ## Answer The survey stages build on each other: the data from one stage is reused and refined in the next, so the work is not repeated and the choice becomes firmer. | Stage | Information used from earlier stage | Information added or updated | |---|---|---| | Map study | Terminal points and obligatory points; policy | Alternative routes on maps, rough lengths and gradients | | Reconnaissance | Routes marked in the map study | Field check of the routes, soil, drainage, geology, land use; some routes rejected; rough cost estimate | | Preliminary survey | Selected route(s) from reconnaissance | Accurate traverse, levelling, contours, hydrology, soil and material data; comparison of alternatives | | Final location and detailed survey | Contour plan and the chosen route from the preliminary survey | Centre line set out, curves, final profile, cross-sections, design details, bill of quantities | #### How the updating is done 1. Map-study routes are **checked and corrected in the field** during reconnaissance (e.g. a route marked over a ridge may be found to pass through a landslide area). 2. The reconnaissance observations on soil, streams and materials are **measured accurately** in the preliminary survey. 3. The preliminary contour plan is used to **fix the centre line**, and minor changes (smoother curves, balanced earthwork, a better stream crossing) are made at the final location. 4. Estimates are updated: rough -> preliminary -> detailed. 5. Any new obstacle found at a later stage can send the study back to the previous stage. Thus the information is continuously **verified, refined and extended** from broad to detailed. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. Why is information from one survey stage reused in the next? A. To make the study broader again B. So that work is not repeated and the choice becomes firmer C. Because maps are always accurate D. To increase cost Answer: B. Each stage builds on and refines earlier data, avoiding repetition and narrowing the options. (Key point: Reuse of data) 2. What happens to routes marked in the map study during reconnaissance? A. They are final and not checked B. They are discarded without study C. They are checked and corrected in the field, e.g. a ridge route may be found to cross a landslide area D. They are only used for cost Answer: C. Routes from maps are verified on the ground and some are rejected. (Key point: Map study check) 3. How is the preliminary survey plan used at final location? A. It is ignored B. It is used to fix the centre line, with minor changes like smoother curves or better stream crossing C. Entirely new routes are chosen D. Only the map study is repeated Answer: B. The contour plan fixes the centre line; small improvements are made during final location. (Key point: Preliminary to final) 4. How do cost estimates change through the stages? A. Detailed, then rough, then preliminary B. They stay the same C. Rough, then preliminary, then detailed D. Only one estimate is made at the end Answer: C. Estimates are updated from rough to preliminary to detailed. (Key point: Estimates) ## Related in Transportation Engineering I - [Stages of engineering survey for alignment](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Asurvey-stages) — Transportation Engineering I, chapter 2, asked 7× - [Reconnaissance survey information](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Arecon-survey-info) — Transportation Engineering I, chapter 2, asked 2× - [Requirements of ideal highway alignment](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Aalignment-requirements) — Transportation Engineering I, chapter 2, asked 12× - [Factors controlling highway alignment](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Aalignment-factors) — Transportation Engineering I, chapter 2, asked 12× - [Definition of highway alignment](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Adefine-alignment) — Transportation Engineering I, chapter 2, asked 4× - [Factors controlling hill road alignment](https://www.bctengineer.com/question.md?key=semester_6%2Ftransportation_engineering_i%3Ahill-alignment-factors) — Transportation Engineering I, chapter 5, asked 2× ## Related in other subjects - [Tunnel alignment survey and ideal bridge location](https://www.bctengineer.com/question.md?key=semester_7%2Ftransportation_engineering_ii%3Atunnel-alignment-survey-ideal-bridge-location) — Transportation Engineering II, chapter 5 - [Geology in road alignment selection](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Aroad-alignment-geology) — Engineering Geology II, chapter 4, asked 5× - [Direct surface methods for road alignment](https://www.bctengineer.com/question.md?key=semester_4%2Fengineering_geology_ii%3Adirect-surface-methods-road) — Engineering Geology II, chapter 4