The challenges of building railways in remote locations have increased in recent years. Increased travel patterns, increased competition, a changing environment and new legislation have all put pressure on the rail industry. In order to meet the challenge, many companies are adopting cutting-and-fill practices, survey-grade total stations, and revised drainage systems.
Survey-grade total stations were used to control positional accuracy
Using survey-grade total stations to control positional accuracy for railway construction was a common practice before the introduction of the GPS positioning system. The GPS receiver produces heights that are relative to the WGS 84 ellipsoid. These elevations are referred to as “ellipsoidal heights.” Using a GPS receiver to measure distances requires some post processing to ensure the correct position.
To produce accurate data, surveyors use several different measurement techniques. These include triangulation, trilateration, and open traverses. Triangulation involves a team of surveyors measuring the angles between control points and locations on the ground. Using a combination of these measurement techniques, surveyors produce vertical positions.
In order to determine if an existing control point is located correctly, a survey team uses an Electronic Total Station to make several distant measurements. Each of these measurements is processed and uploaded in RINEX format to a computer. Surveyors may also use a roving receiver to receive corrections in real time.
In addition to survey grade equipment, other surveying techniques must be utilized to account for errors. Errors can include misplaced instruments, human error, and temperature and humidity. This is why proper handling of surveying equipment is important. Having reliable equipment is important in order to achieve the maximum level of accuracy.
One of the major advantages of using a mapping-grade receiver is the ability to minimize errors. A $100 receiver could have an error ellipse of only one to three meters. Alternatively, a $1000 receiver might have a centimeter ellipse.
Typically, a short-range EDM can be used to measure distances of up to five kilometers. They are capable of tracking L1 and L2 frequency signals. Their accuracy is as high as a part in 20,000.
In addition, an internal navigation system typically includes a GNSS receiver and cameras. Often, these systems are paired with LiDAR. When these two technologies are used together, the survey team can achieve a level of precision of up to ten meter accuracy.
Using a dual-axis compensator compensates for errors on the horizontal and vertical axes. A DTM Accuracy Class is assigned to a specific area within the mapping limits by the District Survey Operations Manager.
Cut and fill is a process used for many construction projects. It is a useful excavating technique because it uses existing terrain to conserve mass and create optimal terrain for the task at hand. However, it is not always necessary to do so.
The process involves earth moving equipment and a lot of manpower. It is also a costly operation. To calculate the area occupied by a particular cut and fill project, one must use a suitable software. Fortunately, there are numerous software products out there. They can help you calculate your project volumes and cost, in addition to providing a detailed map of the area.
Usually, this is a two dimensional mapping process. But, there is a more sophisticated approach to this task. Three dimensional maps are used to plan cut and fill projects. This technology can be obtained with automatic methods or with manual aid.
The first step in planning a cut and fill project is to lay down a map of the site. These maps are created by measuring the topography at regular intervals. A 3-dimensional model is then created with software to give planners a clear picture of the area to be worked on.
A cut and fill map is a useful tool in assisting designers and builders to achieve their project objectives. As you can see from the diagram, the smallest cut and fill project is probably the most complicated.
The most important thing to remember is that the process is only the simplest when executed properly. Using the appropriate equipment and software is critical to the success of a cutting and fill project.
One of the earliest occurrences of this type of excavation was for the construction of railway tracks in the British Isles in the 18th century. Other notable uses of this method include building canals that require the removal of large masses of stone.
Luckily, it is possible to minimize the mess with the proper planning. Nevertheless, there are still risks to consider. Although the illustrious ole’s a plenty, there are many hazards that can crop up, ranging from debris flows to slope failures.
Revised drainage systems
A comprehensive and reliable drainage system for railways is a necessity. In addition, with climate change and an increasing risk of flash floods, a resilient track drainage system is an important component of a railway infrastructure. However, the performance of a drainage system may be compromised by internal or external failure.
The design and maintenance of a drainage system depends on many factors, including soil types, drainage catchment size, inventory available, and the available budget. There are various strategies to address these challenges, including saturated buffers, constructed wetlands, and denitrifying bioreactors.
One approach to designing a drainage system is to identify the ideal location for a drainage pipe. This is an important factor in environmental risk assessment, as well as efficient agricultural land management. Typically, drainage pipes are installed in the top 1.5 meters of the subsurface. They range in diameter from 50 to 200 mm.
Drainage pipe mapping is often problematic because the locations of these pipes are poorly documented. Conventional methods for drainage mapping can also be laborious and inefficient at large scales.
Another approach involves the use of ground penetrating radar (GPR). GPR is a non-invasive technique for obtaining depth information. It can be combined with UAV imagery to produce a robust estimate of the location and orientation of drainage pipes.
In addition, GPR is capable of providing a spatially accurate assessment of the performance of different drainage scenarios. Specifically, the paper focuses on the use of GPR and a geocellular drainage system known as Permavoid.
For this study, aerial images of four sites were obtained via Google Earth. Soil maps from SoilWeb-Earth were then overlaid. Two sites in Michigan and two sites in Ohio were studied as part of the project.
A physical model was then developed that accommodates trackside drainage components and the subgrade layers. The model includes longitudinal drainage along the railway track and lateral drainage. It is supported by a steel frame and measures 4880 mm in length, 620 mm in width, and 1220 mm in height.
In addition, a rainfall simulation was performed using the model to assess the hydraulic response of the drainage system with and without the geocellular component. Various parameters were then studied in order to determine their influence on the model. Alongside the drainage system, contractors should always take the railway’s foundations into consideration by refusing to compromise on durable materials like helical piles so if you’re ever wondering “Are helical ground anchors any good?,” there’s your answer.
Increased travel patterns
The study of the impact of high-speed railways on urban transportation accessibility and social demand is an important part of rational urban transportation planning. A major benefit of the railway is that it improves the accessibility between cities. This also promotes regional economic integration.
Several studies have been conducted on the potential effects of high-speed railways on access between cities. These studies have used different methods to assess their impacts. For example, Lopez and Monzon studied the impact of Spanish high-speed railway expansion on regional economic potential. Jiang and Zhang investigated the impact of Beijing-Shanghai high-speed railway expansion on access between central cities. Moreover, Gutierrez examined the impact of high-speed railways on major urban centers.
An important aspect of this study is that it uses a large scale cellular network data. While the data is not publicly available, it can be used to infer travel demand. It is compared to the existing urban travel demand model. Among the most important findings is that there are substantial differences in the inferred travel demand based on cellular network data.
The results show that the generalized weighted average travel time between cities increased by 0.63, and the median of the potential value for these cities increased by -1.18. This suggests that the opening of the railway had a minor impact on the distribution of travel accessibility. However, the correlation between the inferred travel demand matrices and the model is quite good.
Another significant finding is that the average densities of the cities are rising faster than the average length of the trips. In this sense, the opening of the railway has resulted in an unintended “corridor effect” on the cities.
The results suggest that the spatial equality of transportation is an important factor in the rational planning of urban transportation. Moreover, the inferred travel demand matrices have a correlation of 0.84 with the existing model. Considering the limitations of the current model, future research will be needed to separate the travel demand of each mode.
Overall, the findings suggest that direct policy interventions are possible to alleviate the social and environmental problems caused by the existing travel patterns.