---
title: "Why reconnaissance survey is conducted"
subject: "Transportation Engineering I"
chapter: 2
key: "semester_6/transportation_engineering_i:recon-survey-why"
source: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/recon-survey-why
site: BCT Engineering
---

# Why reconnaissance survey is conducted

Transportation Engineering I · Chapter 2: Highway Alignment and Engineering Survey

- Asked in: 2081 Chaitra, 3 marks
- Video: [Initial Survey for Road || Reconnaissance Survey](https://www.youtube.com/watch?v=g5fRPas1HgQ) — Survey Adviser
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/transportation_engineering_i/recon-survey-why
- Whole chapter: https://www.bctengineer.com/md/semester_6/transportation_engineering_i/chapter-2

## Question

Explain why reconnaissance survey is conducted.

## Short answer

It verifies map-study routes in the field, collecting data on soil, drainage, and land use not shown on maps. It eliminates infeasible routes early, saving time and cost before the detailed preliminary survey, while providing rough cost estimates and identifying key obstacles.

## Answer

A reconnaissance survey is done to check in the field whether the routes chosen in the map study are really feasible.

- **To verify the map study:** maps may be out of date and do not show new buildings, recent landslides, changes in river courses or soil conditions.
- **To collect data not available on maps:** soil, geology, drainage, land use, materials and local conditions.
- **To eliminate bad routes** and keep one to three promising routes for the costly preliminary survey, saving time and money.
- **To locate the obligatory points** and the stream crossing positions.
- **To make approximate estimates** of construction cost and compare the routes.
- **To get a general idea of the problems** (hydrology, slope stability, land acquisition) before the detailed work.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Why is the map study verified in the field?
   A. Maps may be old and miss new buildings, landslides or rivers
   B. Maps are always accurate
   C. Field work is cheaper than map study
   D. To avoid doing the preliminary survey
   Answer: A. Maps can be outdated and show no soil or geology, so field checking is needed. (Key point: Verify map study)

2. Why does reconnaissance keep only one to three routes?
   A. Because only three routes exist
   B. To save time and money in the costly preliminary survey
   C. To avoid cost estimates
   D. To skip final location
   Answer: B. Eliminating bad routes avoids spending on detailed survey of poor options. (Key point: Eliminate routes)

3. Which information is collected that maps do not give?
   A. Contour lines
   B. Latitude and longitude
   C. Scale of map
   D. Soil, geology, drainage, materials and local conditions
   Answer: D. Soil, geology, drainage, land use and materials are field data not on topographic maps. (Key point: Data not on maps)

## Related in Transportation Engineering I

- [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×