WORK NO. 2

DRAWING UP THE LONGITUDINAL AND TRANSVERSAL PROFILES OF THE ROAD USING THE METHOD OF ENDING GEOMETRIC LEVELMENT1. INTRODUCTION:

For these measurements we had more work to do because in that day we were not so many. We think that this helped us because in this way, a few persons which didnt have the chance to do the readings on the stadia, in that day they were abused in order to learn how.The roles were a little bit changed and every person did something else than on the first work. We think that this was a good start for us in taking seriously the true art of being an civil engineer. We managed to take every responsibility on ourselves and this was the best thing to learn that day.An Civil Engineer must work with others but he must not depend on them.After one day spent in the sun, we finally finished the readings.

2. INTRUMENTS AND METHODS

Levelmeters Stadia Tripod

Levelmeter:

Levelmeters are classified into two groups: levels without sniper scope and levels.

Levelmeters without scope are part of simple tools, not used for purely topographical, but to solve various problems in the construction site. In this group includes: the rubber tube and level masons and boards.

Levelmeters as rigorous sniper leveling out of sight of the telescope axis. This leveling is carried out either with toric of level or self-matte, with optical compensator.

1. Toric levels sniper and level, called the classical level, in terms of constructive, fall into two basic types: fine levels screwless horseback riding fine screw levels.

a. The screwless fine horse. Is characterized in that support, bezel and smooth toric form an integral unit having a fixed position to each other. It consists of following parts: bezel (1), the axis of sight L-L; smooth toric (2) for leveling the aiming the telescope axis, with axis D-D', called directrice, tribrach

(3) that supports the whole instrument; foot screws (4). To lock the telescope motion in the horizontal plane about a vertical axis, V-V ', is equipped with a screw or locking lever for moving fine and has a micrometer screw (5).

In this category, used increasingly less often, are levels of NT, NG, Zeiss Ni 060, etc.. These levels are used in technical implementation and site leveling, differences in level determination being made by a mean square error of 10...20mm/km.

Level without fine screw mounted

b. The fine screw mounted. Is characterized in that the rear window and level toric form an integral unit, support device is attached via an articulated traverse from one end to the other end with a screw fine horse, that perimte fine tilt and telescope toric levels. It consists of following parts: Sniper (1), smooth toric (2), tribrach (3), screw mounted (4), screw or locking lever (5), joint (6), riding fine screw (7).

Some levels have graduated horizontal circle, allowing its existence, al-lows the simultaneous determination of vertical position and the position of the plan points. Leveling axis of level targeting is done with ordinary toric or coincidence.

Fine level screw mounted

In this category are older types floors Reiss, Gamma, and newer levels of precision Zeiss Ni 030, Wild N10 and high-precision Zeiss Ni 004.

The optical device of the level coincidence

The level axes are:

Vertical axis (main), V-V ', is the axis passing through the center employ-spy camera vertical position;

Axis or directricea toric levels, D-D 'is tangent to the torus, its middle, occupying a horizontal position;

Axis of the telescope sight, L-L ', is the line joining the lens optical center with wire cross hairs.

The level movements are:

Moving the entire apparatus in the horizontal plane about a vertical axis V-V ', for this movement device has both screw or lever lock and fine motion screw;

Fine movement, limited vertically, only the telescope and level toric, only to screw the fine riding levels;

Move telescope on its axis or change together, only at levels not screw with fine bezel mounted and mobile.

The category level is riding fine screw has two of the most used in practice, namely: Zeiss Zeiss Ni 030 and Ni 004.

2. Sniper levels and optical compensator.

These levels, called compensatory or automatic levels, simplifies the process of measuring pro-leading to increased efficiency of field work. At these levels, leveling the aiming axis is automatic with a compressor, after having first been stalled by a level approximately spherical.

After the manner of construction, compensators can be: the pendulum level and liquid.

Accuracy levels of compensation is the magnification of the telescope and precision compensator. The category level of compensation, are the following types Zeiss Jena Ni-050 - Zeiss Jena Ni-025 - Zeiss-Jena KONl 007.

The Zeiss Jena Ni-050. Level is used in technical leveling and site, particularly the leveling and surface-dynamic execution longitudinal and transverse profiles. Main components: focusing screw, screw fine moving horizontally mounted lever, telescope eyepiece, sight to read the horizontal angle values.

The optical scheme of the level Ni 050

Levelment is a subsection of the surveying which implies the study of the instruments and methods used in order to determine the vertical position of the topo points on the terestrial surface.

Vertical position of any point could be express by the total potential of the respective point respecting to the atraction center of the Earth.

Its difficult to measure the potential for numerous points lead to the vertical positions expression depending on the equipotential surface of the terestrial geoid by level difference called altitude (heights).

The surface of the terestrial geoid is accessible only in the oceans/seas surface where is established the refference points called fundamental zero, depending on are expressed the vertical position on any topo point.

The level differences are measured only for the ground surface, it results in order to express the vertical positions far away from the oceans/seas is necessary to measure, step by step, by intermediate points, until the considered point, starting from the refference fundamental 0.

If the distance is too big, those determinations will be afected by the Earth curvature and also by the atmospheric refraction, being necessary directions.

If the distance is too small, the refference surface could be considered horizontal and are not necessary corrections.

If the distance is too big each point is situated on the proper level surface, aproximative paralel with the geoid surface. The level difference between those two points will be the vertical distance (on the pumb bob direction) between those 2 levels surface. On the points level calculations the Earth curvature will be considered. At the calculus the Earth curvature will be ignored.

On the both situations, if its known the level of a point (for example zA), after the level differences measure zAB between that point A and another B, it results the relation. +

Although, physically, the difference level represents a distance, this will receive an algebric sig depending on the considered sense between those two points. The figures below ilustrate that the difference level considered to point

A to point B will be positive and in reverse from B to A will be negative, so:=

Fig no.1 The level difference between great distances

Fig no.2 The level difference between small distances

Ending geometric levelment

In which one of the points, for example A is considered a station point, so above it, at a height IA the levelmeter is positioned. On point B, we set a topographic stadia in the horizontal position.

Fig no.3 Ending geometric levelment

In this case the horizontal distance between the levelmetere and the stadia is equal to that between the point A and B, DAB is called level.

The levelment difference (zAB) between those two points is the result of the mathemathic difference between the levelment height IA and the value red on the stadia in point B, L0B, at the level of the horizontal plane in which the opthycal axis of the telescope its found. The value L0B is measured between point B and a given plane, so:In this case the value =; 0, the terrain altitude in point B is

greater than that in the point A and the slope is positive; if < 0, then the

slope is negative and the altitude in B is less than the one in A. In this situation

the unknown altitude zB, of the point B will be calculated with:=+ ;

In case in which we apply the ending geometric levelment method the error of non-horizontal of the levelment well affect the measurements results.

The level difference according to the relation above will be:= = = +

So the error will be transmitted in the measurement results, as being in direct relation with the distance between points A and B.

Fig no.4 Error of non-horizontal of ending geometric levelment

The readings on the stadia

The telescope of the levelmeter is stadimetrical, so it allows measuring by opthycal way the horizontal distance between the apparatus and the topographic stadia. The telescopes reticule it allows 3 readings on stadia: 2(superior L2 and the inferior L1) at the stadimetric wires and one (middle L0) at the horizontal reticule wire.

Fig no.5 Readings on stadia

Between the 3 readings on stadia the following relation is given: +

2

which means that L1 and L2 are used for checking L0 value, L0 being used in the difference level calculus.

Furthermore, L1 and L2 allow the calculus of the horizontal distance (because the telescope is horizontal) with the relation: = where K is the stadimetric constant (generally the instruments have K=100).

3. INPUT DATA:

1. The sketch of the required traverse

2. The altitude of the point (Z).The inclined distances, measured directly on the ground using the ruler, between the points of the traverse and between these points and the radiation points.

Sketch

of the

traverse

Stages of drawing up a topographic transversal and longitudinal

profile

1. Finding out the Z of the R5 point.

2. Establishing and drawing up the sketch of the given traverse

3. Marking up the points of the traverse

4. Setting up the instrument in the station point

5. In each point we install the stadia and read L0, L1 and L2.

6. For each station point we make readings forward and backwards (for checking up).

7. After the readings are registered we change the height of the instrument and check the values

8. For each station point the same procedure is applied.

Calculus for a transversal profile:

1. Register the values from the readings

2. We calculate the average value of the instrument heights and of the Lo readings in the 2 positions 3. The level difference is the difference between Ia and Lo

4. The absolute level of a point is the sum between z and Z of the station point

5. With the given values we draw up a topographic plane for each transversal profile and for the longitudinal profile

Example of calculus for the 508 station point:

From 508 we aimed the points: 502, 501, 101, 503, 504, 505, 506, 508, 507, 102, 509, 510, 514, 513, 512, 511, 103, 515. Z508 = 0 m

H1=1,498m. H1=1,522m

=+=1.498 + 1.522= 1.510

2

2

,= 1.555 ;.= 1.610 ;

,=+=1.555 + 1.610= 1.582

2

2

= = ,= 1.510 1.582= 0.0725

+= 0.0725 + 0 =0.0725

Conclusion: We will use the same algorithms for the rest of the points.