SURVEYING FOR

HIGHWAYS ENG. SUNETH THUSHARA

HIGHWY DESIGN DIVISION

RDA

Surveying for Road Construction

• At the onset of any construction project, land surveying serves an integral role.

• Never is this more apparent than in a major civic task such as roadway construction.

• Such a pivotal project needs great precision to execute it perfectly.

• Fortunately, certified land surveyors working with modern, advanced technology can make this happen.

• Land surveys for road construction are implemented at the start of the process as well as throughout building and development.

• The land surveyors can assess land features and elevations, determine the presence of underground obstacles, and identify potential hazards, helping to ensure a smooth process for a well-built motorway.

Engineering Surveys for Highway locations

• Before a highway alignment is finalised in highway project, the engineering

survey are to be carried out. The various stages of engineering surveys are:

• 1-Map study (Provisional alignment Identification).

• 2-Reconnaissance survey.

• 3-Preliminary survey.

• 4-Final location and detailed surveys.

MAP STUDY

• From the map, alternative routes can be suggested in the office, if the topographic

map of that area is available.The probable alignment can be located on the map

from the fallowing details available on the map.

• 1-Avoiding valleys, ponds or lake

• 2-Avoiding bend of river

• 3-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.

MAP STUDY

RECONNAISSANCE SURVEY:

• 1-To confirm features indicated on map.

• 2-To examine the general character of the area in field for deciding the most

feasible routes for detailed studies.

• 3-A survey party may inspect along the proposed alternative routes of the

map in the field with very simple instrument like a bneylevel, tangent

clinometer, barometric…. To collect additional details.

Preliminary survey

• Objective of preliminary survey are:

• 1-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.

• 2-To compare the different proposals in view of the requirements of the good alignment.

• 3-To estimate quantity of earthwork materials and other construction aspect and to work out the cost of the alternate proposals.

Methods of preliminary survey:

• 1-Conventionalapproach-surveyparty:carries out surveys using the

required field equipment, taking measurement, collecting topographical and

other data and carrying out soil survey.

• 2-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.

• 3-Other studies: Drainage, Hydrological survey, soil survey, Traffic and

Material survey.

Methods of preliminary survey:

Methods of preliminary survey:

Location survey:

• 1-Transferring the alignment on to ground.

• 2-This is done by transit theodolite.

• 3-Major and minor control points are established on the ground and centre

pegs are driven, checking the geometric design requirements.

• 4-Centre lines tacks are driven at suitable intervals, say 20m interval in plane

and rolling terrains and 10m in hilly terrain.

Location survey:

Detailed survey:

• 1-Temporary benchmarks are fixed at intervals of about 250m and a tall drainage and underpass structure.

• 2-Earthwork calculations and drainage details are to be work out from the level books.

• 3-Cross sectional levels are taken at intervals of 20min Plane terrain, 10min Rolling terrain, 10 min built –up area, 10 min Hill terrain.

• 4-CBR value of the soils along the alignment may be determined for design of pavement.

• 5-The data during detailed survey should be elaborate and complete for preparing detailed plans, design and estimates of project.

RDA CORRIDOR SURVEY

GENERAL

• Detailed topographic surveys are necessary to develop Detailed Engineering

designs

• RDA is using Civil 3D design software for its road design

• Survey data and details need to be customized to the format required by Civil

3D software

EXISTING AND NEW ROAD

CORRIDORS

• Establishing the preliminary centre line

• Establishing the reference points, control traversing and detailed surveying

• (X,Y,Z) points for all ground points and other necessary points

• Sufficient number of points on the existing road surface and other cross sectional elements.

• Should be able to correctly depict the ground model using tall the points taken

CORRIDOR WIDTHS

• Corridor width is defined to limit the extent of survey work

• For straight stretches, equal widths on both left and right are taken

• Import features in the close vicinity like streams, drains, rivers, lakes

embankments etc should be taken.

• Structures falling partly within the corridor, full structure should be taken

• Curved stretches, more width in inner side of the curve.

GPS points

• If the length of the road is greater than 5km, Control points should be

established at 5km interval

• If the length of the road is 1km-5km, Control points should be established

at the start and end points

• If the length of the road is lesser than 1km, Control point should be

established at the start point

• Three points to be established and inter visible.

TS BETWEEN GPS

• TS established at maximum interval of 250m

• Intermediate points to cover all required features

• Consecutive points inter visible

• Monuments to be firmly fixed

CONTROL TRAVERSE USING TS

• Certificate of Accuracy of Instrument from Department of Surveys

• Every 5km stretch, traverse run between predetermined control points

• If only one GPS, traverse circuit.

• Determine adjusted N E coordinates for all traverse stations.

ESTABLISHMENT OF BENCH MARKS

• Heights from GPS are Ellipsoidal Heights

• Separate level survey to determine to BM levels

• TBM to be established in 250m approx.

• Having established N, E and Z of all GPS Stations and Traverse Stations,

proceed to detailed surveying

DETAILED SURVEYING

FEATURES & STRUCTURES

• All CPP, TSS positions

• All secondary TSS positions

• All PBM and TBM positions

• Edges of Ex. CW

• All temporary and permanent buildings, houses, hunts and other structures

• All roads including widths

• All fences, boundary walls, retainingg walls, gates etc

FEATURES & STRUCTURES

• Ex. Drains, streams, irrigation structures, channels, wells, rivers, bridges and

culverts, km and mile posts

• All electric transmission lines including substations, transformers, electric posts etc.

• Telegraph lines, telegraph posts, control boxes etc.

• All places of religious and historical significance, graveyards, play grounds etc.

• Steep embankments and cuttings

• All systematic and continuous plantations

MAJOR ROAD INTERSECTIONS

• Sufficient length along the crossing road

• Sufficient length along the existing road

• Corridor width is generally larger than that is defined for road.

BRIDGES & RIVERS

• Sufficient length along the river on both sides of the road to be covered.

COORDINATES OF THE GROUND

POINTS

• (N,E,Z) coordinates of sufficient number of ground points to depict the correct topography.

• A cross section across the centre line of the culvert

• Sufficient number of points to represent the correct geometry of bridges, profile of the river bed, topography of the river bank etc

• Location of under and over ground structures, sewer line, water line, telephone line and poles, electric poles etc

• Location of individual trees.

RECORDING AND PREPARATION OF

DATA FILE

• File should be in *.txt (comma, delimited) format or *.xls format. The data

field format is PNEZD

• P-Point number

• N-North Coordinate

• E-East Coordinate

• Z-Elevation

• D-Description

PREPARATION OF COMPUTERIZED

BASE PLAN

• Survey should be plotted in AutoCAD

• Different layers should be used to plot different features.

• The points taken along the Ex. CL should be connected with a polyline

• The points taken along the Ex. LHS Tar Edge should be connected with a polyline

• The points taken along the Ex. RHS Tar Edge should be connected with a polyline

SOUTHERN EXPRESSWAY