Highway Design Data - Field Survey Information and Field Investigations, Soil Investigations PDF

CHAPTER 3 HIGHWAY DESIGN DATA HIGHWAY AND RAILROAD ENGINEERING Prepared by: Engr. Joshua Ferdinand B. Villafuerte, RCE, SO, CBP, MSCE-TrE (Cand.) Civil Engineer/Transport Planner HIGHWAY DESIGN DATA 1. Field...

CHAPTER 3 HIGHWAY DESIGN DATA HIGHWAY AND RAILROAD ENGINEERING Prepared by: Engr. Joshua Ferdinand B. Villafuerte, RCE, SO, CBP, MSCE-TrE (Cand.) Civil Engineer/Transport Planner HIGHWAY DESIGN DATA 1. Field Survey Information and Field Investigations 2. Soil Investigations 3. Existing Pavement Evaluation 4. Drainage Recommendations 5. Design Controls 6. Requirements for Speedy Plan Preparation  FIELD SURVEY INFORMATION AND INVESTIGATION FIELD SURVEY INFORMATION AND INVESTIGATION Possible Restrictions to the alignment: Hills, valleys, steep slopes, rivers, and lakes Elements that are influenced by the surrounding topography: alignment, gradients, cross sections, and sight distance of a highway For example, the presence of hills or steep slopes can impact how curves are aligned and how grades are managed. In flat terrains: topography might not dictate location much, but it can still create challenges for certain design aspects like drainage and managing different grades. FIELD SURVEY INFORMATION AND INVESTIGATION HIGHWAY LOCATION | concerned with gathering of pertinent data for more effective highway planning, design, construction and operation. Various stages of engineering surveys: Map study / Office Projection (provisional alignment identification) Reconnaissance survey Preliminary survey Utility Service Records Final Location Survey FIELD SURVEY INFORMATION AND INVESTIGATION MAP STUDY / OFFICE PROJECTION FIELD SURVEY INFORMATION AND INVESTIGATION MAP STUDY / OFFICE PROJECTION If the topographic map of that area is available, alternative routes can be recommended in the office. NAMRIA - National Mapping and Resource Information Authority The probable alignment can be located on the map from the following details available on the map Avoiding valleys, ponds, or lake Avoiding bend of river If road has to cross a row of hills, possibility of crossing through mountain pass Map study gives a rough guidance of the routes to be further surveyed in the field. FIELD SURVEY INFORMATION AND INVESTIGATION MAP STUDY / OFFICE PROJECTION Multiple route options are explored to find the most cost- effective alignment without requiring extensive surveys. trial and error approach to identify the optimal route considering factors like alignment, grades, sight distances, and compensation. Constraints such as curves, slopes, and ensuring good visibility are taken into account during this process. FIELD SURVEY INFORMATION AND INVESTIGATION RECONNAISSANCE SURVEY FIELD SURVEY INFORMATION AND INVESTIGATION RECONNAISSANCE SURVEY To confirm features indicated on map. To examine the general character of the area in field for deciding the most feasible routes for detailed studies. A survey party may inspect along the proposed alternative routes of the map in the field with very simple instrument like abney level, tanget clinometer, barometer, etc. To collect additional details from alternative routes during this survey: Valleys, ponds, lakes, marshy land, hill, permanent structure, and other obstruction Value of gradient, length of gradient and radius of curve FIELD SURVEY INFORMATION AND INVESTIGATION RECONNAISSANCE SURVEY Details to be collected from alternative routes during this survey are (cont.): Number and type of cross drainage structures High flood level (HFL) Soil characteristics Geological features Source of construction materials (stone quarries, water sources, etc.) Prepare a report on pros and cons of different alternative routes. As a result, few alternative alignments may be chosen for further study based on practical considerations observed at the site. FIELD SURVEY INFORMATION AND INVESTIGATION RECONNAISSANCE SURVEY Proposed Sites for Stream Crossings | The location of a highway when crossing a stream is important for several reasons. Different hydrologic and hydraulic factors come into play when crossing near the confluence of two streams compared to a single stream. In rural areas, there might be greater tolerance for higher backwaters than in urban places. Tidal areas introduce a unique set of hydraulic considerations. Whether the structure is a bridge, or a culvert can affect the hydraulic analysis. Additionally, environmental factors like land use upstream and downstream, energy dissipation needs, debris control, and facilitating fish passage impact the extent of field investigations required for designing a specific solution.  Table: Design Flood Frequencies for Bridges Source: DPWH Design Guidelines Criteria and Standards (DGCS), Volume 3, Water Engineering Projects and Volume 5, Bridge, 2015 Edition Table: Design Flood Frequencies for Road Drainage Source: DPWH Design Guidelines Criteria and Standards (DGCS), Volume 3, Water Engineering Projects and Volume 5, Bridge, 2015 Edition FIELD SURVEY INFORMATION AND INVESTIGATION PRELIMINARY SURVEY FIELD SURVEY INFORMATION AND INVESTIGATION PRELIMINARY SURVEY Objectives of preliminary survey are: To survey the various alternative alignments proposed after the reconnaissance and to collect all the necessary physical information and detail of topography, drainage, and soil. To compare the different proposals in view of the requirements of the good alignment. To estimate quantity of earthwork materials and other construction aspect and to workout the cost of the alternate proposals. FIELD SURVEY INFORMATION AND INVESTIGATION PRELIMINARY SURVEY Methods of preliminary survey are: Conventional approach | survey party carries out surveys using the required field equipment, taking measurement, collecting topographical and other data and carrying out soil survey. Modern rapid approach | by aerial survey taking the required aerial photographs for obtaining the necessary topographic and other maps including details of soil and geology. Finalize the best alignment from all considerations by comparative analysis of alternative routes. FIELD SURVEY INFORMATION AND INVESTIGATION PRELIMINARY SURVEY: HORIZONTAL ALIGNMENT Horizontal alignment involves circular curves, transition curves, and tangents. It aims to ensure safe and uninterrupted travel at a consistent speed for extended road segments. Design considerations include safety, functional classification, desired speed, topography, vertical alignment, construction cost, cultural development, and aesthetics. Properly balancing these factors results in an alignment that is both safe and cost-effective, while also harmonizing with the land's natural contour. A. Circular Curves Simple Curve – a circular curve is an arc with a single constant radius connecting two tangents. The most common type of curve used in a horizontal alignment. Compound Curve - composed of two or more adjoining circular arcs of different radii. The centers of the arcs of the compound curves are located on the same side of the alignment. Broken-Back Curve - the combination of a short length of tangent between two circular curves. Reverse Curve - consists of two adjoining circular arcs with the arc centers located on opposite sides of the alignment. Note: Compound and reverse curves are generally used only in specific design situations such as mountainous terrain. B. Spiral Curves FIELD SURVEY INFORMATION AND INVESTIGATION PRELIMINARY SURVEY: VERTICAL ALIGNMENT Vertical alignment comprises gradients connected by vertical curves. Design controls involve safety, topography, functional classification, design speed, horizontal alignment, construction cost, cultural development, drainage, vehicular characteristics, and aesthetics. "Vertical alignment," "profile grade," and "grade line" are interchangeable terms. The land's topography affects alignment, with three common terrain classifications: level or flat Rolling mountainous FIELD SURVEY INFORMATION AND INVESTIGATION UTILITY SERVICE RECORD Utilities required for a project depend on its location and could involve: 1. Sanitary sewers 2. Water supply lines 3. Oil, gas, and petroleum pipelines 4. Overhead and underground power and communication lines, including fiber optic cables 5. Cable television lines 6. Wireless communication towers 7. Drainage and irrigation lines 8. Special tunnels for building connections FIELD SURVEY INFORMATION AND INVESTIGATION UTILITY SERVICE RECORD Consulting utility service providers and obtaining records for all services in a project area, including their precise locations and depths, brings benefits to both highway agencies and utilities: - Avoidance of unnecessary utility relocations - Reduction of unexpected conflicts with utilities - Enhancement of safety FIELD SURVEY INFORMATION AND INVESTIGATION FINAL LOCATION SURVEY The alignment finalized at the design office after the preliminary survey is to be first located on the field by establishing the center line. LOCATION SURVEY Transferring the alignment on to the ground. This is done by transit theodolite. Major and minor control points are established on the ground and center pegs are driven, checking the geometric design requirements. Center line stacks are driven at suitable intervals, say 50 m interval in plane and rolling terrains and 20 m in hilly terrain. FIELD SURVEY INFORMATION AND INVESTIGATION FINAL LOCATION SURVEY DETAILED SURVEY Temporary bench marks are fixed at intervals of about 250 m and at all drainage and under pass structure. Earthwork calculations and drainage details are to be workout from the level books. Cross-sectional levels are taken at intervals of 50-100 m in plane terrain, 50-75 m in rolling terrain, 50 m in built-up area, and 20 m in hill terrain. Detail soil survey is to be carried out. CBR value of the soils along the alignment may be determined for design of pavement. The data during detailed survey should be elaborate and complete for preparing detailed plans, design, and estimates of project. FIELD SURVEY INFORMATION AND INVESTIGATION DRAWINGS AND REPORTS FOR A HIGHWAY PROJECT Key map Map study Index map Reconnaissance survey Preliminary survey plans Location of final alignment Detailed plan and longitudinal Detailed survey section Material survey Detailed cross-section Geometric and structural Land acquisition plans design Drawings of cross drainage and Earthwork other retaining structures Pavement construction Drawings of road intersections Construction controls Land plans showing quarries, etc. FIELD SURVEY INFORMATION AND INVESTIGATION DRAWINGS AND REPORTS FOR A HIGHWAY PROJECT Key map | should show the proposed and existing roads, and important places to be connected. The size of the plan in general should not exceed 22 x 20 cm. Scale of the map is chosen suitably according to the length of road/highway. Index map | should show the general topography of the area or site. Details are represented using symbols. Index map should also be of suitable scale with size 32 x 20 cm. Preliminary survey plans | are plans showing details of various alternate alignments and all information collected should be drawn to a suitable scale of 10 cm = 1 km to 25 cm = 1 km. FIELD SURVEY INFORMATION AND INVESTIGATION DRAWINGS AND REPORTS FOR A HIGHWAY PROJECT Detailed plan | shows the ground plan with alignment and the boundaries. It shows contours at intervals of 1 to 2 meter in plain terrain and 3 to 6 meters in hilly terrain showing all details including existing structures. Scale of 1/2400 or 1/1200 is suitable for detailed plans. Size of drawing may be 60 x 42 cm approximately. Longitudinal sections | should be drawn to the same horizontal scale of the ground as in detailed plan. Vertical scale may be enlarged 10 times of the longitudinal scale. The longitudinal section should show details such as datum line, existing ground surface, and vertical profile of the proposed road and position of drainage crossings. FIELD SURVEY INFORMATION AND INVESTIGATION DRAWINGS AND REPORTS FOR A HIGHWAY PROJECT Detailed cross-section | are generally drawn to natural scale of 1 cm = 2.0 to 2.5 meter. It should be drawn every 100 meter or where there are abrupt changes in level. In hill roads, the cross-section should be drawn at closer intervals. The cross- section drawing should extend at least up to the proposed right of way. The cross-section number, the reduced distances, and the area of filling or cutting (or both) should be shown on cross-section drawing. Land acquisition plans | are usually prepared from the survey drawings for land acquisition details. These plans show all general details such as buildings, wells, nature of gradients, and other details required for assessing the values. The scale may be 1 cm = 40 meters or less. FIELD SURVEY INFORMATION AND INVESTIGATION DRAWINGS AND REPORTS FOR A HIGHWAY PROJECT Drawings of cross-drainage | are usually drawn to scale of 1 cm = 1 meter. For details of any complicated portion of the structure, enlarged scales up to 8 cm = 1 meter or up to half full size may be employed. However, the size of drawing should not exceed the standard size. Cross-section of streams should be to a scale of not less than 1 cm = 10 meters. Drawing of road intersections | should be prepared showing all details of pavement, shoulders, islands, etc. to proper scale. Land plans showing quarries | where quarries for construction materials are to be acquired for new projects, separate land plans should be prepared. The size of these maps and scales may be similar to those proposed under land acquisition.  SOIL INVESTIGATIONS SOIL INVESTIGATIONS The Geotechnical Engineer's focus is on confirming potential GeoHazards and collecting design information for road construction or enhancement. Detailed analysis of soil types along the road is vital to determine the appropriate investigation methods and equipment. Investigations must adhere to ASTM or AASHTO standards. Soil classification is conducted following the AASHTO system. TYPES OF SURVEYS 1. Subsurface Investigation 2. Subgrade Investigation 3. Widening of Existing Pavements 4. Sampling and Testing SOIL INVESTIGATIONS SUBSURFACE INVESTIGATION Subsurface investigation involves examining the area beneath the subgrade level. Exploration depth along the road alignment depends on geological knowledge, soil surveys, prior investigations, and road configuration. In regions with simple conditions of light cut and fill, exploration should reach a minimum depth of 1.5 meters below the planned subgrade. In cases of deep cuts, substantial embankments over marshland, or indications of weak layers in the subsurface, exploration depth varies. Determination of depth takes into account existing topography and the characteristics of the subsoil. SOIL INVESTIGATIONS SUBGRADE INVESTIGATION Subgrade investigation examines the soil surface under the pavement. On existing roads, auger borings and test pits are conducted at suitable intervals along the road's centerline. Boring locations alternate between the center and edge of the pavement. Bore profiles are logged to determine pavement thickness, material condition, and subgrade soil type. Subgrade material samples are taken for on-site soil classification. Test pits are placed at intervals along the road, covering different subgrade soil types. SOIL INVESTIGATIONS SUBGRADE INVESTIGATION Pits are logged, with small samples taken for soil classification from all layers (base, sub-base, subgrade). In-situ density testing follows AASHTO T 191 standards for the subgrade layer. Large samples are taken for Moisture-Density-CBR relationship observation and other tests. Road raising or new construction needs sampling and testing of in- situ material and select fill source for proper subgrade data. High embankment or roadside cut sections (>3 m) require deep borings for geotechnical analysis (slope stability, settlement). Volume 2C provisions guide the formulation of the geotechnical investigation program. SOIL INVESTIGATIONS WIDENING OF EXISTING PAVEMENTS Widening existing pavements involves using the same method as described in Subsurface Investigation. Auger boring and classification of in-situ materials into groups are conducted. Representative test pits are taken, and in-situ and laboratory testing is done. 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. Pavement widening needs a design depth at least as thick as the existing pavement. SOIL INVESTIGATIONS SAMPLING AND TESTING: IN-SITU Pits and boreholes must be logged properly using the standard sheet from DGCS Volume 2C. Log details should include layer thickness, color, type, and visual description of each layer (e.g., asphalt, gravel, clay-loam, brown, yellow), depth below the surface, and water levels if present. For auger holes, take small samples of subgrade for on-site soil classification following AASHTO T 88 or T 27. In test pits, take small and large samples, perform an in-situ density test as per AASHTO T 191. SOIL INVESTIGATIONS SAMPLING AND TESTING: LABORATORY TESTS Subgrade samples from test pits and boreholes need 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 must be prepared in line with AASHTO T 87 procedures. BIBLIOGRAPHY Department of Public Works and Highways Bureau of Design (2015). Design Guidelines, Criteria and Standards – Volume 4. Hoel, L. A., Garber, N. J., & Sadek, A. W. (2008). Transportation Infrastructure Engineering: A Multi-Modal Integration. Khanna, S. K., Justo C. E. G., & Veeraragavan A. (2014). Highway Engineering. Nem Chand & Bros.