Monday, July 30, 2012

Planning a Route For A New Railway - And How Digital Maps Assist

Whenever a new railway development is being considered, a survey is particularly useful both for the construction and also to plan for ongoing maintenance. Surveyors will spend time mapping out the best possible routes for the railway and will also confer with engineers on details such as gradient, ground type and practicality of the possible route. It is essential that a site visit is carried out before any portrayals are made so that any geographic issues can be seen in order to assess whether they are going to cause an issue.
Blueprints can then be drawn up by the surveyors and given to the engineers and the construction firm. The surveyors are involved at every stage and should continue to be consulted all the way through the whole process so that nothing is left to chance and to ensure that everything from laying the track to positioning of signal poles and stations is done properly.
In a perfect world, the railway line would run in a straight line from start to finish without any changes in gradient. If that were indeed the case, there would be probably be no need for a surveyor in the first place. However, as we do not live in a perfect world, this is not likely and there are certain rules that a railway surveyor needs to follow when planning a new railway route.
The first is that any gradient must be no steeper than two units high for every one hundred units forward. The second is that when it comes to corners, no more than ten degrees can be considered. This is why it is so important to be aware of the lay of the land beforehand. Other relevant information includes the track gauge and the maximum number of carriages to be pulled.
The railway surveyor is mostly concerned with the track and whilst there are other issues to think about such as the height and width of the track, clearance of either side and so on, the system will not be able to work correctly if the rails themselves are not correctly placed. Other aspects of railway design include bridges and tunnels and these can be very challenging. This is where the engineers input is essential as they will be required to build the bridges and tunnels. The surveyor will design cuttings and embankments beside the track and be in charge of ensuring the track remains centered.
Modern mapping technology has made planning new transport routes much simpler. It is now common practice to use aerial photography, Geographic Information Systems, CAD and height data to create a plan for a new transport route. Making use of other information such as green belt data, sites of special interest, local town planning policies and where existing road and rail routes are, all contribute to producing several different types of visual display as well as 2 and 3D models.
When building starts, by making use of laser imagery combined with specialist software, the surveyors can identify the integrity of the materials and ensure that the railway is properly positioned and centered. The laser technology is also useful once the route is in use for maintenance teams who can easily identify areas that require attention. Being able to take advantage of all this modern technology has enabled both surveyors and engineers to create plans for and build accurately new railway routes.

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