Class 1 level reference Points

For Taiwan class 1 level reference net, there are 2,065 new class 1 level reference points planned. Among them, in year 1999 and 2000, the class 1 grade 1 level reference net for Taiwan island loop were established first. There are 1,010 units of class 1 level reference point survey work (level reference route total length is around 2,020 km). In year 2001 and 2002, the class 1 grade 2 level reference net, totaling 1,055 units of class 1 level reference point survey work (level reference route total length is around 2,110 km).

The level reference points are set up along the level reference routes. The set up procedures are, in sequence, selection of points, and lay stone at the selected points.

The principles of selection points for the level reference points are:

  1. For the new level reference points along the level reference routes, the set up principle is average 1 point for every 2 km.
  2. For the new level reference point, as much as possible to select the points with a distance over 200 m from the existing level reference points set up by other organizations.
  3. The point shall not interfere with the safety of man and vehicle traffic.
  4. The point shall be not registered public land that is geological stable and no partial slide. The priority of selections are governmental organization, school, group, park, square, green area, monument, interchanger, or rest area etc. suitable areas. If the level reference route shall pass through military barricade, the points shall be over 200 m from the barricade.
  5. The areas surrounding the point shall be able to maintain existing status for a long period of time, and will not be used for any other purposes.
  6. The point shall not be directly on the road surface. If they are to be located on the median stripe or sidewalk, their width shall be over 1 m, and there shall be no under ground piping and trench. If the level reference passes through narrow mountain roads, they shall be set up on the empty lots on the roadsides.
  7. Easy to access, for convenient to survey or used by all engineering applications.
  8. Investigate the landownership information of the points, and acquire agreement from the landowners or land management organizations.
  9. Good aerial visibility, the cover of angle of altitude for the point, in the 360 degree horizontal angle, at least 60% shall be less than 40 degree.
  10. Keep away from radio stations, television broadcasting station, radar station, microwave station, high voltage wires and other electromagnetic wave sources. This is to avoid wireless wave interfere with the receiving of satellite signals.
  11. Within short distances, there are no electromagnetic wave reflective bodies (such as metal plates, barbed wires and flat type reflective body) to reduce multi-route effects.
  12. When making point selection, if the requirements from item 9 to item 11 could not be satisfied, they may be loosen. However, for every 4 points, at least one shall meet all requirements.
  13. The nodes for the level reference net shall be set up in accordance to the level reference points point selection principle item 2 to item 11 requirements.

When lay stone for the level reference point, please pay attention to the following items:
  1. When lay the points, use #316 stainless steel materials. The normal surface (include dirt surface and hard surface) points laying method is as shown Figure 2. The upper most movable cover shall be casted with organization full name, class and installation date. The indentation of the removable cover shall be located toward north. The material of the movable cover shall be brass or stainless steel. The diameter is 16.5 cm. The frame outside diameter is 22.5 cm. The internal diameter is 14.5 cm. The thickness is over 10 cm. The words are engraved with Chinese Kai style number 50 (around 1.7 cm square). The engraving width and depth is 0.2 cm. The laying methods for bedrock and bridge points are as shown in Figure 3. However, if the points are located on the bridge, they shall be located at the abutments at the ends of the bridge.
  2. The complete stainless steel mark (use #316 stainless steel material, 8 cm diameter, the maximum thickness of the center extended area is at least 2.2 cm. The edge thickness is 1.0 cm) shall be formed in one piece as spherical arc. On the center is a cross. The cross length is 1.5 cm. Both width and depth are 0.1 cm. The cross is painted in red. The words on the stainless steel mark are engraved with Chinese Kai type No. 28 (around 0.8 cm square). The engraving width and depth are 0.1 cm and paint in red. The specifications for the stainless steel mark and stainless steel rod are as shown in Figure 4. The material shall have testing certificates from Industrial Technology Research Institute Industrial Material Research Laboratories.
  3. When carrying out the stone laying, cover the stainless steel rod (use #316 stainless steel material, diameter is 6/8¡¨, around 1.90 cm.) with copper casing. Uses hammer over 8 pounds, starting from the head of the installer down to knock on the rod. Continue until that the stainless steel could not go down deeper any more with ten consecutive knocks. Between two stainless steel rods and the joints between stainless steel mark and stainless rod, they shall be glued together with AB glue. Record the number and length of the stainless steel rods.
  4. The concrete used shall have cement, sand and stone ratio as 1:2:3. Or, the concrete strength is over 3000 psi (210 kg/cm2). The installation shall be in stages. After the concrete at the bottom level solidified (wait at least 12 hours), refill with earth. Lay a layer of thin plastics, the upper layer is then covered with concrete and fix the movable cover.
  5. After the point installation is completed, install a large pebble at each of the four corners of the point location. (The length shall not be less than 35 cm. The maximum width shall be at least 15 cm.) This is to protect the safety of the point location. The surface of the large pebble and concrete shall be painted with yellow waterproof paint.
  6. Between the first and second installation period, there shall be safety sign set up to protect the safety of pedestrians. After the installation is completed, all the construction debris shall be removed and cleaned out. Finally, beautify the point location and surrounding areas (within 2 m).

(1)Point installation side view

Point installation side view

(2)Location installation front view

Location installation front view

(3)Bedrock and bridge point installation methods

Bedrock and bridge point installation methods

(4)Schematics of stainless steel mark and stainless steel

Schematics of stainless steel mark and stainless steel

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