Lesson Note On Field procedure for setting out the curve with Theodolite

Field procedure for setting out the curve

1. A theodolite is set up at the point of curvature T1, and get it temporary adjusted. 2. The vernier A is set to zero, and get the upper plate clamped. After opening the lower plate main screw, sight the point of intersection, V. Then the lower plate main screw gets tightened and get the point V bisected exactly using the lower plate tangent screw. Now the line of sight is in the direction of the rear tangent T1 V and the vernier A reads zero. 3. Open the upper plate main screw, and set the vernier A to the deflection angle Da. The line of sight is now directed along the chord T1 a. Clamp the upper plate. 4. Hold the zero end of the tape of a steel tape at T1. Note a mark equal to the first chord length C1 on the tape and swing an arrow pointed at the mark around ‘a' till it is bisected along the line of sight. The arrow point then indicates the position of the first peg ‘a'. Fix the first peg at ‘a'. 5. Unclamp the upper plate, and set the vernier A to the deflection angle Db. The line of sight is now directed along T1 b. 6. With the zero end of the tape at a, and an arrow at a mark on the tape equal to the normal chord length C, swing the tape around b until the arrow is bisected along the line of sight. Fix the second peg at the point b at the arrow point. It may be noted that the deflection angles are measured from the tangent point T1 but the chord lengths are measured from the preceding point. thus, deflection angles observed are cumulative in nature but chord lengths swung are individual in nature. 7. Repeat steps (5) and (6) till the last point is reached. The last point so located must coincide with the tangent point T2 already fixed from the point of intersection.

Lesson Note On Setting out of Foundations

Setting out of Foundations

Before Commencement, of the excavation of trenches for foundation, a setting out plan is prepared on paper. The setting out plan is a dimensioned ground floor plan, usually drawn to scale of 1:50. The plan is fully dimensioned at all breaks and openings. One of the methods of setting out of foundations is to first mark the centre line of the longest outer wall of building by stretching a string between wooden pegs driven at its ends. This serves as the reference line for marking the centre line of all the walls of the building. The centre line of the wall, which is perpendicular to the long wall, is marked by setting up a right angle. Right angle is set up by forming triangles with sides 3,4and5units long. If we fix the two sides of the right angles triangle to be 3 m, and 4 m, then the third side i.e. the hypotenuse should be taken a 5 m. The dimensions should be set out with a steel tape. The alternative method of setting out right angle is by the use of theodolite. This instrument is also helpful in setting out acute or obtuse angles. Small right-angled Projections are usually set out with mason’s square.

The method of  Setting out of Foundations described above is not so reliable for important works as there is likelihood of the wooden pegs being pulled up or displaced. In an accurate method, the centre lines of the building walls arc carefully laid by means of small nails fixed into the head of the wooden pegs driven at the quoins. In case of rectangular buildings, the diagonal from the opposite corners are checked for their equality. Small brick walls, pillars or platforms are constructed 9ocm clear of the proposed foundation trench. The platforms are about 15 cm wider than the trench width and are plastered at top. The tops of all platforms or pillars should be at the same level preferably at plinth or floor level of building. The strings are then strenched over the nails in the pegs and the corresponding lines are marked on the wet plastered platforms top by pressing the stretched string on the plastered surface by a trowel. The outside lines of thefoundation trench and the plinth lines are marked on the wet plastered platform top in the similar manner.

Before starting excavation, the strings are stretched between the outside lines of thefoundation trench marked over the platform top and the cutting lines are marked on the ground by lime powder. If necessary, the lines may be marked by a daghbel or pick-axe.

LESSON NOTE ON TWO THEODOLITE METHOD FOR SETTING OUT A CURVE

TWO THEODOLITE METHOD FOR SETTING OUT A CURVE

RANKINE'S METHOD In this method, curves are staked out by use of deflection angles turned at the point of curvature from the tangent to points along the curve.

This method is based on the following geometry:

 Let AB & BC be two tangent intersecting

at B, the deflection angle be (shown infig.)

 the tangent length is calculated &

tangent pt. are marked.

 Let,

= first pt. on the curve.

= length of cord.

= deflection angle for first chord.

R = radius of curve

= total deflection for the chord.

 Procedure:-

i. Set the instrument up at the tangent point, sight along the tangent and turn off the first deflection angle ( Φ =Ө/2 ).

ii. Fix one end of tape at A, measure off 'c' meters, and swing tape until it aligns with the line of sight. Put in peg B.

iii. Turn theodolite a further Φ°. Fix one end of tape at B, measure off 'c' meters, and swing tape until that point on the tape crosses the line of sight. Put in peg C. iv. Repeat step (iii) until you peg the curve. If the line of sight becomes obstructed, then simply set up on any peg on the curve, sight back along the chord to the previous peg and continue to establish the deflection angles.

 Precautions to take:

Calculate the angle Φ to seconds, or errors will be considerable if many pegs must beplaced.

The final reading, to the other tangent point, should equal L.

Aim: To set out the simple curve by two theodolite method.

Instruments Required : Two Theodolites and Ranging rods.

Principle: The angle between the target and the chord is equal to the angle which that chord subtends in opposite segment.

Given : Chainage of the curve , angle of intersection and Radius of curve (R).

Procedure :

1. Prepare a table of deflection angle for the first sub chord, Normal chord and last sub chord .

2. Set up one theodolite over T1 and another over T2 .

3. Direct the instrument at T1 to the ranging rod at the point of intersection B and bisect it.

4. Direct the instrument at T2 to the first target point T1 and bisect it.

5. Set the verniers of both the theodolites to read zero.

6. Set the first deflection angle (D1) on both theodolites so that the telescopes are in the direction of T1D and T2D respectively.

7. Move the ranging rod until it is bisected by the cross hairs of both the theodolites to locate the point D on the curve .

8. Set the second value of deflection angle on both the theodolites and repeat the step 7 above to get the location of E.

9. Continue the process for obtaining the locations of other points in a similar manner.

Lesson Note On Site Setting Out / Field Setting Out

Site Setting Out / Field Setting Out
	The method of setting out is the reverse of surveying process. The process involves the positions and levels of building lines and road alignments shown on the construction plans to be established on the ground by various techniques and instruments. See Also: Setting Out Circular Curves Methods of Setting Out Setting out buildings by coordinates Setting out with theodolite and level Checking verticality Setting out and alignment in steel framed buildings Alignment and verticality in form work Control and calculation for route surveying
1. Setting Out Building by Coordinates A building can be set out by taking referencing from an already established baseline. An irregular building or a building having a complex geometry can be also be located using the same method. For each corner of the building, a grid line can be established from the baseline. 3. Checking Verticality: To check verticality of points in a building, the following surveying instruments can be used: Plumb Bob (For buildings less than 20m in height) Optical Plummet (A transparent plastic sheet is used as a target for checking verticality of tall buildings) Theodolite Setting out works also include Computations and setting out Methods for: Simple Circular Curves Compound Curves Reverse curves Transition curves Vertical curves

Lesson Note on Types of Surveying

Types of Surveying
	Surveying has a broader scope of application. Its importance is felt in the following areas and/ or services: Agricultural surveying services Building control regulations Building defects Building maintenance and repairs Building refurbishment Building surveying Commercial property agency Commercial property management Commercial property valuation Commercial property dispute resolution Commercial rent review (and lease renewals) Dilapidations General practice Home buyers’ survey and valuation Insolvency advice Industrial property agency Industrial property valuation Hotel and licensed property Property investment advice Rating advice and appeals Residential property valuation Rural practice Annual developmental study Economic growth review Production and consumption statistics Transportation Communication Mapping Definition of legal boundaries for land ownership
Classification Of Surveying Surveying is indispensable to a number of human endeavour, which use surveying principles and practice to their required areas of application. The types of surveying and application are identified and explained below: ALTA / ACSM survey Archaeological survey Agricultural development survey As-built survey Bathymetric survey Construction survey Deformation survey Engineering survey Erosion and Sediment control plan Foundation survey Geological survey Hydrographic survey Mortgage survey or physical survey Plot plan or site plan Soil survey Sub division plan Tape survey Topographic survey Wet lands Delineation and Location survey. 1. ALTA, ACSM Survey: This a surveying standard jointly proposed by the American Land Title Association and the American Congress on surveying and mapping that incorporates elements of the boundary survey, mortgage survey, and topographic survey. ALTA/ACSM Surveys, frequently shortened to ALTA surveys, are often required for real estate transactions. 2. Archaeological survey: Used to accurately assess the relationship of archaeological sites in a landscape or to accurately record findings on an archaeological site. 3. Agricultural Development Survey: It is a survey carried out to assess the production, yield studies, growth, and the development of agricultural sector taken over a specified period of time saying 2001-2008. 4. As–build survey: Is a survey conducted several times during a construction project to verify, for local state and federal boards, that the work authorized was completed to be specifications set on the plot plan or site plan. This usually entails a complete survey of the site to confirm that the structures, utilities, and roadways proposed were built in the proper locations authorized in the plot plan or site plan. As – built survey is usually done 2-3 times during the building of a house, once the foundation has been poured, one after the walls are put up, and at the completion of construction. 5. Bathymetric survey: This is a survey carried out to map the seabed profile. 6. Boundary survey: A boundary survey to establish the boundary of a parcel using its legal description which typically involves the corners or restoration of monuments or markers at the corners or along the lines of the parcel, often in the ground, or nails set in concrete or asphalt in the past, wooden posts, blazes in trees, piled stone corners or other types of monuments have also been used. A map or plat is then drafted from the field data to provide a representation of the parcel surveyed. 7. Construction Survey: This is otherwise described as “Lay-out” or “setting out”. It is the process of establishing or marking the position and detailed layout of new structures such as roads, or buildings for subsequent construction. Surveying is regarded as a sub-discipline of civil engineering all over the world. All degree and diploma level engineering institutes world wide have detailed items of surveying in the curriculum for undergraduate courses in the discipline of civil engineering. 8. Deformation Survey: This is a survey carried out to determine if a structure or object is changing shape or moving. The three dimensional positions of specific points on an object are determined. A period of time is allowed to pass and these positions are then re- measured and calculated, and a comparison between the two sets of positions is made. 9. Erosion and sediment control plan: This is a plan that is drawn in conjunction with a sub division plan that denotes how up coming construction activities will affect the movement of storm water and sediments across the construction site and into abutting properties and how developers will adjust grading activities to limit the depositing of more storm water and sediment into abutting properties than was done prior to construction 10. Foundation survey: A survey done to collect the positional data on the foundation that has been poured and is curved. This is done to ensure that the foundation was constructed in the location authorized in the plot plan, site plan, or sub division plan. When the location of the finished foundation is checked and approved, the building of the remainder of the structure can commence. This should not be confused with an As-built survey which is not to be done until a particular lend of work is completed on the required stage. 11. Geological Survey: It is a generic term for a survey conducted for the purpose of recording the geologically significant features of the area under investigation. In the past in the remote areas, there was often no base topographic map available, so, the geologist also needed to be a competent survey or to produce a map to the terrain, on which the geological information could then be draped. More recently, satellite imagery or aerial photograph is used as a base, where no published map exists. Such a survey may also be highly specialist for instance focusing primarily on hydro-geological, geochemical or geomagnetic themes. 12. Hydrographic Survey: Hydrographic survey is a survey conducted with the purpose of mapping the coast line and seabed for navigation, engineering, or resource management purposes. Products of such surveys are nautical charts. 13. Mortgage survey or physical survey: It is a simple survey that generally determines land boundaries and building locations. Mortgage surveys are required by title companies and lending institutions when they provide financing to show that there are no structure encroaching on the property and that the position of structures is generally within zoning and building code requirements. Some jurisdictions allow mortgage surveys to be done to a lesser standard, however most modern Nigerian minimum standards require the same standard of care for mortgage surveys as any other survey. The resulting high price of mortgage surveys has led some lending institutions to accept mortgage inspections not signed or sealed by the surveyor. 14. Plot plan or site plan: It is a proposal plan for a construction site that include all existing and proposed conditions on a given site. The existing and propose conditions always, include hydrology, drainage flows, endangered species habitat, among others. 15. Soil survey: This is also called soil mapping. It is the process of determining the soil types or other properties of the soil covered over a landscape, and mapping them for others to understand and use. 16. Subdivision Plan: It is a plot or map based on a survey of a parcel of land. Boundaries lines are drawn inside the larger parcel to indicate the creation of new boundary lines and roads. The number and location of plats, or the newly created parcels, are usually discussed back and forth between the developer and the surveyor until they are agreed upon. At this point, monuments, usually in the form of square concrete blocks or iron rods or pins are driven in to the ground to mark the lot corners and curve ends, and the plat is recorded in the cadastre or land registry. In some jurisdictions, the recording or filling of a subdivision plat becomes, in effect a contract between the developer and the city or country, determining what can be built on the property and under what conditions. Always upon finally completion of a subdivision, an As-built plan is required by the local government. This is done so that the roadway constructed therein will pass ownership from the developer to say local government by way of a contract called a covenant. When this stage is completed, the roadways will now be maintained, repaved, swept, and plowed (if necessary) by the local government. 17. Tape survey: This type of survey is the most basic and inexpensive type of land survey. Popular in middle part of the 20th century, tape surveys while being accurate for distance, lack substantially in their accuracy of measuring angle and bearing. Considering that a survey is the documentation of half (1/2) distance and half (1/2) bearing, this type of survey is no longer accepted among local, state or federal regulatory committees for any substantial construction work. 18. Topographic survey: This is surveys that measures the elevation of point on a particular piece of land, and present them as contour lines on a paper. 19. Wetland Delineation and location survey: This is a survey that is completed when construction is to be done on or near a site containing defined wetlands. Depending on the local state, and federal regulations, wetlands are usually classified as areas that are completely inundated with water more than two weeks during growing season. The boundary of the wetlands is determined by observing the soil color, vegetation, erosion patterns, scour marks, hydrology and morphology. Typically blue or pink coloured flags are then placed in key locations to denote the boundary of the wetland. A survey is done to collect data on location of the placed flags and a plan is drawn to reference the boundary of the surrounding plots or parcels of land and the construction work proposed within. BUILDING SURVEYING Building surveying emerged in the 1970s as a profession in the United Kingdom by a group of technically minded general practice surveyors. Building surveying is a recognized profession within Britain and Australia. In Nigeria in particular, due to risk mitigation/ limitation factors, the employment of surveyors undertaken in Nigeria are broad but include: Construction design and building works Project management and monitoring Property Legislation Adviser Insurance assessment and claims assistance Defect investigation and maintenance adviser Building surveys and measured surveys Handling planning applications Building inspection to ensure compliance with building regulations. Undertaking pre-requisition surveys Negotiating dilapidations claims Design Maintenance Repair Refurbishment Restoration of constructed works.

Lesson Note On Maintenance of Surveying Equipments

Maintenance of Surveying Equipment
	Surveying equipment is being used under most stressful conditions. The equipment is exposed to extreme weather conditions, used in dusty construction areas and is subject to bumpy transportation. Proper care in the method by which equipment is used, stored, transported, and adjusted is a major factor in the successful completion of the survey. Lack of good maintenance practices not only causes unjustified replacement costs, but also can serious the efficiency and accuracy of the entire survey. General Care and Maintenance of Surveying Equipment and Tools Surveying instruments, which include theodolites, levels, total stations, electronic measuring devices, and GPS receivers, are designed and constructed to provide years of reliable use. The shafts, spindles, pendulums, and electronics of precision instruments, although constructed for rugged field conditions, can be damaged by one careless act, or continued negation prescribed procedures for use, care, and adjustment of the instrument.
Each new instrument is furnished with an operator’s manual. The manual contains a description of the instrument, specifications of its various components and capabilities, and applications. The manual also contains basic instructions for use of the instrument and describes recommended servicing and adjusting methods. The operator’s manual should be kept with the instrument at all times. Each operator should thoroughly study the manual prior to use of he instrument, particularly whenever prescribed field adjustments are to be made. If the manual is lost, stolen, or damaged beyond use, a replacement copy should be obtained as soon as practicable. The following general principles of care and servicing should be applied as a routine matter for all survey equipment and supplies. §  All equipment and tools should be kept as clean and dry as practicable, particularly if they are to be transported or stored for any length of time. §  Wooden surfaces should be wiped clean of caked mud or moisture prior to returning the equipment to the vehicle. The original painted or varnished surfaces should be repaired as often as needed to keep moisture from entering the wood. §  Metal surfaces should be cleaned and wiped as dry as practicable. A coat of light oil should be applied to tapes and the metal parts of tools to prevent rusting during storage. Excess oil should be wiped off. Routine Care of Surveying Instruments. §  Before making the first set up of the day, visually inspect the instrument for cracks, bumps, and dents. Check the machined surfaces and the polished faces of the lenses and mirrors. Try the clamps and motions for smooth operation (absence of binding or gritty sound). §  Frequently clean the instrument externally. Any accumulation of dirt and dust can scratch the machined or polished surface and cause friction or sticking in the motions. §  Dirt and dust should be removed only with a clean soft cloth or with a camel hair brush. §  Non-optical parts may be cleaned with a soft cloth or clean chamois. §  Clean the external surfaces of lenses with a fine lens brush and , if necessary, use a dry lens tissue. Do not use silicon treated tissues, as they can damage the coated optics. It is permissible to breath on the lens before wiping it, but liquids, such as oil, benzene, water, etc., should never be used for cleaning purposes. DO NOT loosens or attempt to clean the internal surface of any lens. §  Cover an instrument whenever it is uncased and not being used for any length of time, particularly if there is dust or moisture in the air. After an instrument has been used in damp or extremely cold situation, special precautions must be taken to prevent condensation of moisture inside of the instrument. When working with the instrument in cold weather, it should be left in the carrying case in the vehicle overnight. If stored in a heated room overnight, the instrument must be removed from the carrying case. If the instrument is wet or frost covered it should be remove it from its case, and leave it at room temperature to dry out. 3. Care in Transporting Surveying Equipment. Vehicular Transport §  The major damage to equipment and tools occurs when they are being placed into or taken out of the survey vehicle. Other damage occurs during transport, when equipments is jostled against other tools or equipment. Compartments (lined with carpeting, when possible) should be provided to keep equipment and supplies separated. This not only keeps the equipment from being damaged, it facilitates finding such items more rapidly. Heavier items should be carried in the lower parts of vehicles and they should never be in direct contact with other tools or equipment below them. §  The care, organization, and general housekeeping of a vehicle are good indications of the attitude of the entire survey crew. Keep passenger compartments free of unnecessary clutter and equipment. Any equipment or material carried in the passenger compartment should be firmly secured. §  Transport and store instrument in positions that are consistent with the carrying case design. Many instrument cases indicate the position in which they should be transported. Treat optical targets, prisms, and staffs with the same consideration. §  Transport the instruments in their carrying cases placed in a compartment cushioned with firm poly foam or similar material to protect them from jolting or excessive vibrations. §  Remember, loose equipment, out of place tools, and general clutter not only contributes to damage of the items, they also waste crew time in locating them and are a safety hazard. Casing and Uncasing Before removing an instrument, study the way it is placed and secured in the case. The instrument must be replaced in the same position when returned to the case. In removing the instrument from the case, carefully grip it with both hands, but do not grip the vertical circle standard or where pressure will be exerted on tubular or circular level vials. Field Transport of Surveying Instrument Do not “shoulder” or carry a tripod mounted theodolite or electronic distance measuring equipment (EDM). These instruments should always be removed from the tripod and secured in their carrying cases when moved. These precautions are necessary because the center spindle (center spigot or standing axis) of a theodolite is hollow and relatively short. When carried horizontally while on the tripod, the alidade’s weight is an excessive load for the hollow centerpiece to bear. Instrument damage can result if the above precautions are ignored. Also, the instrument fastener can break, causing the theodolite to fall. 4. Care During Instrument Setups Whenever possible, select instrument stations where operation is not dangerous to the instrument operator, the crew, or the instrument. Select stable ground for the tripod feet. Do not set an instrument closely in front of, or behind, a vehicle or equipment which is likely to move. Take a safe route to all setups. At the site, firmly plant the tripod with its legs widespread. Push along the legs, not vertically, downward. On smooth surfaces, use some type of tripod leg restrainer to keep the legs from sliding outward. Always have the tripod firmly set over the point before removing the instrument from its carrying case. Immediately secure the instrument to the tripod with the instrument fastener. Never leave an instrument or its tribrach on the tripod without securing either to the tripod. Moderate pressure on the fastener screw is sufficient. Excessive tightening causes undue pressure on the foot screws and on the tribrach spring plate. Make sure the tribrach clamp is in the lock position. 5. Adjustments of Surveying Instruments. Field Adjustments The crew leader should develop a set of test procedure to be used frequently for elimination of gross errors. Such tests should include a check of items such as the level, optical plummet, and tripod. In the field, adjustments should only be made when the instrument results are poor or require excessive manipulation. Normally, each instrument should be periodically checked at a facility where the best conditions for testing are possible. Only the adjustments described in the manual for the instrument should be made in the field or shop. Do not “field strip” (dismantle) instruments. Major Adjustments When an instrument has been damaged or otherwise requires major adjustments, it will need to be sent to an authorized repair shop. The instrument should be accompanied by a written statement indicating the types of repairs needed. In the case of electronic devices, the request should describe conditions under which the instrument does not function properly, i.e. coldness, dampness, etc. if a “loaner” is needed, this should also be indicated. 6. Care of Tools Improperly maintained tools can be a source of annoyance, as well as being a safety hazard. Each employee is responsible for keeping his or her tools and equipment in good condition. To prevent loss of small equipment and tools, avoid laying them on the ground, on vehicles, or on equipment which might be moved. When not in use, carry them in scabbards and pouches. Repair or replace any driving tool that is burred or fractured on any part of the striking or driving face. Many surveyors have been injured by the “shrapnel” effect from gads and sledges which had ragged edges. The same is true for “bull points” or other tool which are driven. Crooked or warped handles can cause injury as well as mistitling and damage to the tool. Promptly replace such handles and those that are cracked or broken. Handles should be firmly secured in all cutting and driving tools. 7. Care of Theodolites and Total Stations §  Although the instruments are ruggedly built, careless or rough use and unnecessary exposure to the elements can seriously damage them. If handled reasonably, they will provide consistently good result with a minimum of downtime for repair or adjustment. Some general guidelines for the care of instruments are: §  Lifting – instruments should be removed from the case with both hands, gripping the micrometer knob standard and base on the older instruments. Newer instruments are equipped with a carrying handle; the other hand should support the base. One hand should continually support the instrument until the tribrach lock is engaged and the tripod fixing screw secured. §  Carrying Tripod - In most cases, the instrument should be removed and re-cased for transportation to a new point. If the point is nearby, the instrument should be carried in the vertical position (tripod legs pointing straight down). An instrument should never be “shouldered” or carried horizontally. §  Adjusting collimation – The collimation error of theodolites and total stations is determined by following the procedure outlined in the users’ manual. If the collimation error is found to be consistently in excess of ten seconds on the horizontal and twenty seconds on the vertical, the instrument should be adjusted. The collimation adjustment should be made in the field only by a specially trained individual. Otherwise, the instrument should be returned to an authorized repair shop. 8. Care of EDM Devices §  EDMs are designed, contracted and tested to withstand normal field conditions. They are however, precision instruments and should be handled with the same degree of care required for other types of precision survey equipment. §  Secure EDM in vehicles in padded compartments with substantial the downs so movement and jarring are minimized. Cushion with firm polyfoam or similar material. Do not use soft foam rubber. The instruments should be stored and transported in the position indicated on the case. §  Required maintenance of most EDMs is minimal. However, protection from the elements and routine external cleaning is necessary. §  NEVER point an EDM directly at the sun. The focused rays of the sun can damage sensitive internal parts. §  Protect EDMs from excessive heat. Heat can cause erratic readings and deterioration of components. Do not leave instruments in closed vehicles that are parked in the sun. Avoid rapid changing temperature, particularly from extreme cold to warm, which can cause condensation in the internal parts of the instruments. Condensation can normally be avoided by leaving the instrument in its carrying case for at least 10 minutes and then opening the case to allow any trapped moisture to evaporate. An instrument taken from a warm office or vehicle to an extremely cold operating environment may require some time to adjust itself. The same type of precautions should be taken to let the instrument cool off slowly. §  Although EDM instruments are water resistant and well shielded, keep them as dry as practicable. The case should be opened and the instrument allowed to dry in a warm dry room when not in sue. §  Frequent partial discharge and charge of batteries could cause the battery to lose its ability to hold power. Periodically, batteries should be discharged completely and then recharged overnight, or for the specified charge time. Effective usage of batteries will also decrease at low temperatures. An EDM in the tracking mode position will discharge the battery will also decrease at low temperatures. An EDM in the tracking mode position will discharge the battery quite rapidly, so it is important to be able to charge batteries to their maximum capacity. In general, one should follow the user’s manual instructions on how to maintain the batteries for top performance. If the batteries still fail to hold power, they should be re-celled or replaced. 9. Care of Tapes §  Routine care extends tape life. The following are basic guidelines for the care of tapes. §  Do not place a tape where it can be stepped on or run over, unless the tape is flat, taut, and fully supported on a smooth surface. Keep the tape straight when is used. When pulling a slack tape, a loop can develop into a kink and easily break the tape. Avoid pulling a tape around poles or other object, as a hard pull can stretch or break the tape. §  Do not wind tapes overly tight on their reels, as it can cause unwanted stresses and lead to stretching of the tape. §  After the day’s work, clean tapes that are soiled. In wet weather, dry before storing. Clean rusty tapes with fine steel wool and cleaning solvent or kerosene. Use soap and water when tape is dirty or muddy. To prevent rust after cleaning, oil lightly and then dry the tape. §  Avoid storing in damp places. 10. Care of Tribrachs Tribrachs are an integral part of the precision equipment and should be handled according. They should be transported in separate compartments or other containers to prevent damage to the base surface, bulls eye level, and optical plummet eye piece. Over tightening of the tripod fastener screw can put undue pressure on the leveling plate. 11. Care of Tripods A stable tripod is required for precision in measuring angles. A tripod should not have any loose joints or parts which might cause instability. Some suggestions for proper tripod care are: Maintain firm snugness in all metal fittings, but never tighten them to the point where they will unduly compress or injure the wood, strip threads or twist off bolts or screws. Tighten leg hinges only enough for each leg to just sustain its own weight when legs are spread out in their normal working position. Keep metal tripod shoes tight and free of dirt. Keep wooden parts of tripods well painted or varnished to reduce moisture absorption and swelling or drying out and shrinking. Replace top caps on tripods when not in use. 12. Care of Levels Review the previously stated guidelines for the care of instruments. These guidelines are also generally true for the proper care of pendulum levels. Additional guidelines are. Do not spin or bounce pendulum levels, as such movement can damage the compensator. Protect the level from dust. Dust or foreign matter inside the scope can cause the compensator’s damping device to hang-up. Frequently check the adjustment of the bull’s eye bubble. Adjust the bull’s eye to the center, not almost to the center. Make certain it is adjusted along the line of sight and transversely as well. Proper adjustment reduces the possibility of compensator hang up. To check for compensator hang up, slightly tap the telescope with a pencil or operate the fine movement screw jerkily to and fro. If the instrument has a push button release, use it, if the compensator is malfunctioning, send the instrument to an approved repair service for servicing. Do not attempt compensator repair in the field. 13. Care of Leveling Rods. Leveling rods should be maintained and checked as any other precision equipment. Accurate leveling is as dependent on the condition of the rods as on the condition of the levels. Reserve an old rod for rough work, such as measuring sewer inverts, mud levels, etc. The care requirements common to all types of rods are:- Protect from moisture, dirt dust and abrasion Clean graduated faces with a damp cloth and wipe dry. Touch graduated faces only when necessary and avoid laying the rod where the graduated face will come into contact with other tools, objects, matter, or materials where damage might result. Do not abuse a rod by placing it where it might fall, throwing, and dropping, dragging, or using it as a vaulting pole. Keep the metal shoe clean and avoid using it to scrape foreign matter off a bench or other survey points. If possible, leave a wet rod uncovered, unclosed, and extended until it is thoroughly dry. Store rods, either vertically (not leaning) or horizontally with at least three point support, in a dry place and in their protective cases. Periodically check all screws and hardware for snugness and operation Periodically check accuracy by extending the rod to its full length and checking its scale with an accurate tape. This should be done at the beginning of control level surveys. If the rod indicates a tendency to be “off”, it should be checked each time it is extended.