| Railroad surveys are conducted either during the | | | | surveyor is mostly concerned about the track, |
| initial design and construction process or to aid in | | | | since no other design elements will be relevant if |
| ongoing maintenance projects. Surveyors assist | | | | the track is unusable. Other than providing location |
| engineers in the mapping of optimal rail routes, | | | | input, the surveyor may also create a 2D or 3D |
| and also determine optimal grades, slopes, and | | | | representation of the site. Often this takes form |
| curves in varying sections of the rail route. | | | | as a cross section, allowing viewers to see how |
| The railroad survey is an essential step before | | | | the railway will look from the site itself. In other |
| any drawings can be made of potential railway | | | | cases, the surveyor's work takes the form of a |
| routes. It is necessary to understand the | | | | 3D computer generated image showing the line's |
| geographic restrictions and the layout of the area | | | | ideal location when current geography is |
| before attempting to determine the best route. In | | | | considered. This image may be manipulated to |
| an ideal world, the rail line would run in a perfectly | | | | allow viewing from any side or angle. |
| straight line from start to finish, with no changes | | | | Perhaps the most challenging part of rail road |
| in slope and no turns, since this would be the | | | | surveying is the necessity of bridges and tunnels. |
| shortest distance. If this were possible, a | | | | The surveyor may be responsible for providing |
| surveyor may not be necessary. However, in the | | | | input on site selection and monitoring the building |
| real world there are geographic obstacles that | | | | process to ensure that the bridge or tunnel is |
| nearly always make this impossible. | | | | located correctly. The surveyor's job is made |
| As the surveyor determines the optimum rail | | | | more difficult when tunnels are involved rather |
| route, there are a few restrictions to keep in | | | | than bridges, as the tunnel must be bored |
| mind. First, the rail line should climb no more than | | | | completely straight through the hill or mountain. |
| two meters in altitude for every 100 meters | | | | Once blueprints for the rail line have been created, |
| traveled. When it comes to curve, gentle curves | | | | the surveyor again plays an important role at the |
| (under 10 degrees) are optimum, though tighter | | | | railway site, in determining that the construction |
| curves may be possible or even necessary in | | | | crew has accurately located the rail line on the |
| some areas. One major difference between | | | | physical land when given the blueprint. From laying |
| highway surveying and railway surveying is in how | | | | the track perfectly level and in the proper location |
| angles are measured. On highways, curves are | | | | to following a blueprint to determine where the |
| defined using the ARC method, while railway | | | | platforms and stations should be placed, a |
| surveyors use the Chord Method. This method | | | | surveyor is involved in every step of the way. |
| allows for easier determination of curves in the | | | | The surveyor's job continues to signal poles, |
| field. When determining optimum route, the | | | | electrical wiring, drainage, and other aspects of |
| surveyor also takes into account the track gauge | | | | the railroad project. Various laser devices are |
| (how far apart one rail is from the other), and | | | | often used to gain an accurate depiction of the |
| regulations such as maximum train length, if any | | | | railway area. In some cases, these lasers can also |
| exist. | | | | evaluate the integrity of the track material itself, |
| During this step of the railroad design process, the | | | | a valuable tool for maintenance crews. |