The first is several important basic concepts.
The topographic map scales commonly used in road engineering are 1: 2000 and 1: 1 10,000. The former is used in the survey and design stage, that is, preliminary design and construction drawing, while the latter is used in the preliminary work, that is, feasibility and feasibility.
Of course, there are also large-scale ones, such as 1: 500 and 1: 1000, which are generally used for detailed design of important construction sites. Smaller scales, such as1:50,000,1:65438+100,000,1:200,000, are generally used to make large-scale corridors and route schemes in preliminary work. These will be explained in detail in the specific design work later.
Generally speaking, topographic maps with the scale of 1: 1 10,000 and smaller used in preliminary work can be purchased from local provincial surveying and mapping departments. Relevant certification materials, such as project contract, power of attorney, bid-winning notice, etc. , need to provide. And before buying, we must sort out the range of topographic maps that need to be used, and the combing method will be explained in detail in the previous work route design.
Generally, there is no topographic map of 1: 2000 and larger scale used in the survey and design stage. Please ask the surveying and mapping department to provide it after measuring according to your project scope. Generally, the compound has its own surveying and mapping department, and it can also entrust a unit with surveying and mapping qualifications. Major projects may require aerial survey. Generally, every province has a provincial institute of remote sensing information surveying and mapping, and there are a large number of aerial photos of the province. If there is a large aerial photography in the project area, let them do it, which can save the cost of renting a plane to shoot.
Since it is called topographic map, the most important information is of course terrain, and terrain information is mainly reflected by contour lines. Every time we look at the topographic map, we have to imagine the topography of the site through contour lines. In practical work, reading more and using more can quickly establish the connection between the site and the topographic map.
There are generally two kinds of contour lines, the first curve and the second curve. The first curve is the basic curve, which is drawn at vertical intervals and is thinner on the topographic map. Draw a plane curve every five first curves, which is convenient to calculate the elevation and is shown in bold on the topographic map.
Through the contour lines, we can generally clearly judge the basic topographic units such as mountain tops, ridges, saddles, cliffs and valleys.
Ground objects are generally represented by ground object symbols, and the attributes of corresponding ground objects can be easily found through legends. Many features are the control factors of our highway design, so we should identify them carefully and try not to miss them, such as high-voltage towers, which are easy to miss.
Typical terrain category
Plains, hills and mountains
The route selection of highway projects is often controlled by geological factors. In general, geological conditions require professional geologists to go to the site to carry out relevant geological surveys and even drilling work. But some geological factors can also be found from the topographic map. Such as landslides, steep cliffs and karst.
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