Podcast
Questions and Answers
Which of the following factors is NOT considered when using the trial and error approach to identify the optimal route?
Which of the following factors is NOT considered when using the trial and error approach to identify the optimal route?
What is a primary purpose of conducting a reconnaissance survey?
What is a primary purpose of conducting a reconnaissance survey?
During a reconnaissance survey, which instrument is suitable for simple elevation measurements?
During a reconnaissance survey, which instrument is suitable for simple elevation measurements?
Which of the following is NOT typically collected during a reconnaissance survey?
Which of the following is NOT typically collected during a reconnaissance survey?
Signup and view all the answers
What might significantly impact field investigations required for bridge design over a stream?
What might significantly impact field investigations required for bridge design over a stream?
Signup and view all the answers
Why might there be a greater tolerance for backwaters in rural areas compared to urban settings?
Why might there be a greater tolerance for backwaters in rural areas compared to urban settings?
Signup and view all the answers
What type of observations are crucial when determining the location of a stream crossing?
What type of observations are crucial when determining the location of a stream crossing?
Signup and view all the answers
Which factor is directly affected by whether a structure is a bridge or a culvert?
Which factor is directly affected by whether a structure is a bridge or a culvert?
Signup and view all the answers
What is the primary objective of the preliminary survey in road construction?
What is the primary objective of the preliminary survey in road construction?
Signup and view all the answers
Which of the following methods is NOT described as part of the preliminary survey?
Which of the following methods is NOT described as part of the preliminary survey?
Signup and view all the answers
Which factor is NOT considered when designing horizontal alignment in road construction?
Which factor is NOT considered when designing horizontal alignment in road construction?
Signup and view all the answers
What characterizes a simple circular curve in horizontal alignment?
What characterizes a simple circular curve in horizontal alignment?
Signup and view all the answers
Which of the following is a component of horizontal alignment?
Which of the following is a component of horizontal alignment?
Signup and view all the answers
What is the ultimate goal of balancing factors in horizontal alignment design?
What is the ultimate goal of balancing factors in horizontal alignment design?
Signup and view all the answers
What is the primary purpose of fixing temporary benchmarks at intervals of about 250 m?
What is the primary purpose of fixing temporary benchmarks at intervals of about 250 m?
Signup and view all the answers
Which statement best describes the role of drainage design in road construction?
Which statement best describes the role of drainage design in road construction?
Signup and view all the answers
What interval is used for cross-sectional levels in rolling terrain?
What interval is used for cross-sectional levels in rolling terrain?
Signup and view all the answers
Which is NOT a consideration when estimating quantities for earthwork materials during the preliminary survey?
Which is NOT a consideration when estimating quantities for earthwork materials during the preliminary survey?
Signup and view all the answers
Which map should show proposed and existing roads as well as important places to be connected?
Which map should show proposed and existing roads as well as important places to be connected?
Signup and view all the answers
What is the maximum size for a key map according to the guidelines?
What is the maximum size for a key map according to the guidelines?
Signup and view all the answers
The detailed plan of a highway project includes which of the following elements?
The detailed plan of a highway project includes which of the following elements?
Signup and view all the answers
Which survey plans are used to show details of various alternate alignments?
Which survey plans are used to show details of various alternate alignments?
Signup and view all the answers
What is the purpose of determining the CBR value of soils along the alignment?
What is the purpose of determining the CBR value of soils along the alignment?
Signup and view all the answers
What is the ideal contour interval for hilly terrain as depicted in a detailed plan?
What is the ideal contour interval for hilly terrain as depicted in a detailed plan?
Signup and view all the answers
What is the minimum design depth for pavement widening in relation to the existing pavement thickness?
What is the minimum design depth for pavement widening in relation to the existing pavement thickness?
Signup and view all the answers
Which of the following is NOT a required laboratory test for subgrade samples from test pits and boreholes?
Which of the following is NOT a required laboratory test for subgrade samples from test pits and boreholes?
Signup and view all the answers
Which of the following details must be logged when recording pits and boreholes?
Which of the following details must be logged when recording pits and boreholes?
Signup and view all the answers
Which AASHTO standard is used for the mechanical analysis of subgrade samples?
Which AASHTO standard is used for the mechanical analysis of subgrade samples?
Signup and view all the answers
What guideline must be followed for soil classification from the subgrade samples?
What guideline must be followed for soil classification from the subgrade samples?
Signup and view all the answers
What is the minimum depth of exploration for subsurface investigation in regions with light cut and fill conditions?
What is the minimum depth of exploration for subsurface investigation in regions with light cut and fill conditions?
Signup and view all the answers
Which method is used for examining the soil surface underneath pavement during subgrade investigation?
Which method is used for examining the soil surface underneath pavement during subgrade investigation?
Signup and view all the answers
What is the focus of the subgrade investigation?
What is the focus of the subgrade investigation?
Signup and view all the answers
What is one of the primary factors that determines the exploration depth during subsurface investigation?
What is one of the primary factors that determines the exploration depth during subsurface investigation?
Signup and view all the answers
When conducting subgrade investigation, where are samples for soil classification taken from?
When conducting subgrade investigation, where are samples for soil classification taken from?
Signup and view all the answers
For how deep should borings be conducted in cases of high embankments or roadside cut sections greater than 3 meters?
For how deep should borings be conducted in cases of high embankments or roadside cut sections greater than 3 meters?
Signup and view all the answers
Which standard is followed for in-situ density testing of the subgrade layer?
Which standard is followed for in-situ density testing of the subgrade layer?
Signup and view all the answers
What is involved in the process of widening existing pavements?
What is involved in the process of widening existing pavements?
Signup and view all the answers
Study Notes
Reconnaissance Survey
- Confirms map features and examines general character of the area for feasible routes
- Uses simple instruments like abney level, tangent clinometer, barometer
- Collects details like valleys, ponds, lakes, marshy land, hills, permanent structures, and obstructions
- Determines gradient values, gradient lengths, and curve radii
- Identifies number and type of cross drainage structures, high flood levels, soil characteristics, geological features, and sources of construction materials
- Compiles a report on pros and cons of different routes
- Selects few alternative alignments for further study based on site observations
Proposed Sites for Stream Crossings
- Highway crossing location influences hydrologic and hydraulic factors
- Considerations vary for crossings near confluences, single streams, rural areas, urban areas, and tidal areas
- Bridge or culvert type impacts hydraulic analysis
- Environmental factors impact field investigations for design solutions which include:
- Upstream/downstream land use
- Energy dissipation requirements
- Debris control
- Fish passage facilitation
Preliminary Survey
- Objectives:
- Surveying alternative alignments proposed after reconnaissance
- Collecting topographic, drainage, and soil information
- Comparing proposals based on alignment requirements
- Estimating earthwork material quantities and construction costs for proposals
- Methods:
- Conventional: Survey party using field equipment, measurements, and data collection for topography, drainage, and soil
- Modern Rapid: Aerial surveys using photographs to obtain topographic maps, soil, and geology details
- Finalizes the best alignment through comparative analysis of routes
Preliminary Survey: Horizontal Alignment
- Includes circular curves, transition curves, and tangents
- Designed to ensure safe and uninterrupted travel at consistent speed
- Design considerations include:
- Safety
- Functional classification
- Desired speed
- Topography
- Vertical alignment
- Construction cost
- Cultural development
- Aesthetics
- Circular Curves:
- Simple Curve: Single constant radius connecting tangents, most common type
- Compound Curve: Two or more adjoining circular arcs with different radii
Final Location Survey: Detailed Survey
- Temporary bench marks are fixed at 250 m intervals and drainage structures
- Earthwork calculations and drainage details are derived from level books
- Cross-sectional levels are taken at intervals based on terrain type:
- 50-100 m in plane terrain
- 50-75 m in rolling terrain
- 50 m in built-up areas
- 20 m in hilly terrain
- Detailed soil survey is conducted, including CBR value determination for pavement design
- Provides complete and elaborate data for preparing detailed plans, designs, and project estimates
Drawings and Reports for a Highway Project
- Key map: Shows proposed and existing roads, and important connected places, with a scale appropriate to the project length
- Index map: Shows general topography, details are represented by symbols, with a size of 32 x 20 cm
- Preliminary survey plans: Shows details of various alternate alignments and collected information, with a scale of 10 cm = 1 km to 25 cm = 1 km
- Detailed plan: Shows ground plan with alignment and boundaries, contours at intervals, existing structures, and soil classification following AASHTO system
Soil Investigations: Subsurface Investigation
- Examines the area beneath the subgrade level
- Exploration depth varies based on:
- Geological knowledge
- Soil surveys
- Prior investigations
- Road configuration
- Minimum depth is 1.5 m below the planned subgrade in simple conditions
- Varies based on:
- Deep cuts
- Embankments over marshland
- Weak subsurface layers
- Takes into account topography and subsoil characteristics
Soil Investigations: Subgrade Investigation
- Examines the soil surface under the pavement
- Auger borings and test pits are conducted at intervals along the road centerline
- Boring locations alternate between the center and edge of pavement
- Bore profiles are logged to determine:
- Pavement thickness
- Material condition
- Subgrade soil type
- Subgrade material samples are taken for on-site soil classification
- Test pits are placed at intervals along the road to cover different subgrade soil types
- Pits are logged with samples taken for soil classification from all layers
- In-situ density testing follows AASHTO T 191 standards for the subgrade layer
- Large samples are taken for moisture-density-CBR observations and other tests
- Road raising or new construction requires sampling and testing of in-situ material and select fill sources
- High embankment or roadside cut sections (> 3 m) require deep borings for geotechnical analysis and slope stability investigations
Soil Investigations: Widening of Existing Pavements
- Uses the same method as Subsurface Investigation
- Auger boring and classification of in-situ materials are conducted
- Representative test pits are collected and in-situ and laboratory testing is performed
- Boring and test pit locations are usually beneath the shoulder in the widening area
- Subgrade samples are taken below the level of the existing pavement
- Design depth must be at least as thick as the existing pavement
Soil Investigations: Sampling and Testing (In-situ)
- Pits and boreholes are logged using standard sheets from DGCS Volume 2C
- Log details include:
- Layer thickness
- Color
- Type
- Visual description
- Depth below surface
- Water levels (if present)
- Small samples of subgrade are taken for on-site soil classification following AASHTO T 88 or T 27 for auger holes
- In test pits, take both small and large samples, perform an in-situ density test as per AASHTO T 191
Soil Investigations: Sampling and Testing (Laboratory)
- Subgrade samples require the following laboratory tests:
- Mechanical Analysis: AASHTO T 88 or 27
- Specific Gravity: AASHTO T 100 or 84 or 85
- Atterberg Limits: AASHTO T 89 or 90
- Moisture-Density Relationship: AASHTO T 180 or 99
- CBR% (California Bearing Ratio): AASHTO T 193
- Natural Moisture Content
- Soil classification follows AASHTO M 145 guidelines
- All dry samples are prepared in line with AASHTO T 87 procedures
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
This quiz covers the key concepts of reconnaissance surveys and their importance in selecting feasible routes for stream crossings. It examines the tools used for assessment and factors influencing highway crossing locations. You'll learn about the environmental considerations and technical aspects involved in these surveys.
