Railway operators manage far-flung fleets of highly mobile assets running on thousands of kilometres of maintenance-intensive infrastructure. Geospatial systems are helping them reduce costs and increase utilisation of tracks and facilities
In the post-recession economy, most businesses operate under parameters they cannot control. The transportation segment feels the external pressures more than most. To understand why, we need only to look at the macro forces that are affecting the railway industry. Commodity prices are rising, affecting both supply and demand for goods that travel by rail. Fuel prices are fluctuating along a relentlessly upward trend and railway networks are under pressure from increased freight usage and passengers. Demand for environmental protection is increasing, as are requirements for social responsibility. Some regions are experiencing a high rate of retirement of experienced railway workers.
On the other hand, because of their inherent advantage in fuel efficiency per ton-kilometre, railways could see more cargo move from trucks onto trains. Increased use of high-speed passenger rail can reduce congestion at airports and on highways. For the railways serving the port cities, the growing ocean traffic presents an opportunity to upgrade their infrastructure to handle the flood of cargo and containers. But the broader use of trains presents new challenges. The railway infrastructure is already busy and more capacity will be needed.
For most railway operators, these are compelling forces to better utilise existing assets, primarily the thousands of kilometres of track. Trackage is a finite resource and railway companies need to run larger trains at more frequent intervals. Where possible, they want the trains to move at higher speeds. This introduces a paradox in railway maintenance operations-more traffic on a line results in increased need for maintenance. At the same time, the available maintenance windows (downtime available to perform the maintenance) are shrinking because of the traffic load. It's a familiar problem: do more in less time. One of the most effective approaches is to improve the speed and productivity of inspections and the resulting maintenance and repairs.
Geospatial technology contributes to this effort in two ways. First, it can gather large amounts of data on the railway assets and then analyse the data to produce actionable information. Second, it can help speed up maintenance and repair activities to ensure more efficient use of labour and materials.
THE GEOSPATIAL IMPACT
To see how the various geospatial technologies can be used in railway development and operation, we can break a railway project into four phases: pre-design; design; construction operations, maintenance and safety. While a new railway will go through all four phases, we can also apply the last three to existing networks.
Pre-design and decision phase
New rail lines are emerging in many regions. Developing nations use railways to provide basic transport for people and goods whereas economic growth in developed regions often calls for new or expanded service. To provide the capacity, railways can enlarge existing lines or develop new routes. Both approaches call for extensive planning.
In the pre-design phase, planners conduct feasibility and other analyses to determine the physical, financial and socio-economic impacts. Geospatial technology delivers much of the data needed for these studies, including aerial imagery, cadastral information and environmental data. The results include large-scale maps and terrain models. Mapping and GIS systems can provide good vehicles for preliminary route selection, but detailed feasibility studies must go much deeper as routing options are narrowed down.
As part of the process, geospatial alignment planning software uses the multi-source data to develop optimal routes. For example, consider a project to build a new rail line from a new mine to an ocean port. Alignment planning software considers construction and operating costs, environmental impact, land acquisition and other factors. A tunnel might cost more to construct, but it will result in a shorter route that reduces transit time and fuel costs. The software develops and tests multiple route alternatives and makes recommendations based on optimising the interrelated variables.
Design
When the project moves to the design phase, the volume and detail of geospatial data increase. The objective is to collect and manage accurate information on the physical and cadastral conditions over the project area.
In addition to aerial imagery, the engineering and design work requires ground-based measurements to produce the needed precision and detail. Topographic information and existing circumstances, including ownership, crossing roads, utilities and infrastructure, all play key roles in the design phase. Surveygrade optical and GNSS equipment are common tools at this stage and ground or airborne LiDAR is used as well. Environmental impact data can be gathered using GIS data collection equipment.
During this stage, one of the most important activities for railway operators is to plan and implement their infrastructure for measurement and positioning. The reference framework for 3D optical and GNSS positioning is essential for accurate design, and for the construction and life-cycle phases yet to come. Networks of GNSS reference stations are becoming common around the world. Often established as part of a construction plan, a GNSS network can provide positioning for the railway as well as a wide array of government and commercial applications and users. Reference monuments for optical work can be installed during the design phases as well. As construction progresses, new monuments can be placed where needed to ensure good accessibility for as-built surveys and during the maintenance and operations stages of the projects.
Construction
The role of geospatial technology during railway construction is similar to that of any large engineering project. Functions such as earthwork and grading utilise survey- grade GNSS and optical systems for layout, automated machine control, inspections and quality control.
Geospatial technology is especially important in projects such as tunnels and complex earthworks. Precise surveys provide control and alignment verification, quality inspections and data for volume calculations. Throughout construction, the geospatial systems collect as-built data on the final location of the track and new facilities. The data become part of the railway database which serves as the basis for maintenance and life-cycle projects.
During construction, GNSS and optical sensorsincluding 3D scanners-can be used to monitor deformation and subsidence around large excavations, in slide areas and in and above tunnels.
In addition to laying track, railway construction often includes new stations, maintenance facilities and other buildings. These projects use geospatial technology in the same way as other building construction. Large, complex rail stations (the new La Sagrera station in Barcelona covers more than 295,000 m2) benefit from the use of BIM (building information models) to manage the three- and four-dimensional information about the building. BIM information includes structural components, mechanical systems, utilities and other aspects. Geospatial systems provide layout and quality control during construction and gather as-built information that the BIM uses for operations and maintenance.
Operations, maintenance and safety
While geospatial systems deliver enormous benefits during the feasibility, design and construction phases, they can play an even bigger role during the operational phase of a railway. This is because the operational phase is the largest and most costly part of the railway life cycle (Figure 1). And in a business that is based on moving objects from one place to another, the value of geospatial technology springs from its core ability to do its work while in motion.
For obvious safety reasons, most maintenance of way (MOW) work requires train traffic to be stopped. Operators must plan their work to limit MOW stoppages to periods of low activity.
Figure 1: Typical distribution of costs of railway facilities in the life cycle. The time frame is 30 to 50 years.
Source: Service Track Management, Balfour Beatty Rail, 2010
We can break the safety and maintenance (or operational) phase into three components: fixed and mobile asset management, inspection and documentation and deformation monitoring. Each of these areas can benefit from geospatial technology. It all begins with georeferenced spatial information. Visits to railway companies often reveal ongoing efforts to digitise old, paper track charts and get them georeferenced and moved into a GIS. From there, companies can use airborne systems to scan or photograph their lines and extract the various features into GIS or BIM applications to manage the fixed assets.
The next level of fixed asset management provides more precise information on existing tracks. To collect this data, surveyors can use a small trolley that is simply pushed along the tracks by a single operator. GNSS or optical systems measure the trolley's position and other sensors on the trolley capture the cant and gauge of the track. Over the longer term, we can expect customised mobile mapping equipment and software to handle the bulk of the inspection and documentation load.
Even something that seems as simple as weed control can benefit from geospatial technology. In Europe, a national railway authority uses weed-spraying systems that automatically sense weeds and deliver the spray. The system utilises GNSS to capture the locations of the spraying and avoid environmentally sensitive areas. Even more complex than managing fixed assets is managing a railway's rolling stock that involves tracking the position and status of complex, highly mobile equipment.
Finally, deformation monitoring is an important part of safety and maintenance operations. As in the construction phase, precise sensors can detect motion in structures and landforms. Control software analyses the data from the various sensors and issues alerts when movements exceed specified levels. The monitoring systems can be tuned to detect movement ranging from slow motion over long periods to abrupt, rapid motion that might indicate a structural problem. Monitoring systems can be set up using combinations of total stations, GNSS and geotechnical sensors.
It is difficult to overstate the importance of the spatial reference framework for railway management. Because every feature in the railway's geographic database is tied to spatial data, the positioning information must be completely reliable. The ideal positioning infrastructure blends an active real-time GNSS network with fixed stations and reference points for optical measurements. The planning, installation and maintenance of the positioning framework should receive the same care and attention as the rail beds, bridges and other critical structures.
GATHERING STEAM
For the railway operators looking forward, the contribution of geospatial technologies will grow. Large-area remote sensing and mapping will aid in feasibility and planning. Positioning networks will support the spatial activities for the railways and surrounding communities, including design, construction and monitoring. Mobile mapping, imaging, feature extraction and geospatial data management will become key parts of maintenance and operations.
The common element among these solutions is the ability to collect, fuse and utilise the information from the growing array of geospatial sensors. We should expect to see specialised data acquisition platforms ranging from handheld computers to customised railcars and unmanned aerial vehicles. Data management will ensure the flow of information between systems for GIS, design and maintenance. Enterprise management can improve by tying spatial components into the decision and transaction processes.
The essential geospatial element is the positioning technology, which is the fundamental tool for a railway to address shrinking maintenance windows. By ensuring that the proper positioning infrastructure is in place, railway operators can achieve increased performance and efficiency over the immediate and long-term time frames.
