TRANSPORT DEVELOPMENT TENDENCIES AND REVOLUTION IN ROAD AND RAILWAY SECTORS
Faculty of Civil Engineering- Roads and Railways, Ss. Cyril and Methodius University, Macedonia
Email: [email protected]
The significance of the transport systems operations and transport infrastructures used as a tool to promote socioeconomic development is very evident from an economic perspective, regarding the benefits such as: increased productivity, discovery of new markets, and increased economic growth driven by trade competitiveness. Accordingly, transport infrastructure facilitates to improve the life quality of people, and build a foundation for socio-economic development of community. The most usable transport modes in daily life are roads and railways. In this research the focus will be on comparative analysis between the usage of roads and railways transportation mode on global level.
First part of the research includes usage of primary data sources in the relevant international institutions and also already done researches for road and railway mode. These documents will be used to compare the tendency in the past through the appropriated indicators for road and railway transport. As for the second part of the research, it is proposed to use some new indicators to get the answers for some questions about environmental aspect, transport infrastructure, surface and demography, economic indicators linking with transport activities and transport infrastructure.
The tendency of the research is to find the answer of these two questions using the comparative method and the method of induction: Are railway up to 600km/h (Swiss metro-or magnet railways “Maglev”) or Nanotech road going to be the future of the most used and cost-effective way of transport? and Are “smart materials” going to build the most efficient and secure nano-infrastructure?. Having all this information from statistical analysis, we are closer to the conclusion which type of transportation is more practical and cost-effective regarding the specificity of country and also we would notify the future strategies and probable innovations for improvement of both studied transport modes. Transport is on the brink of a new era of “smart mobility” where infrastructure, transport means, travelers and goods will be increasingly interconnected to achieve optimized door-to door mobility, higher safety, less environmental impact and lower operation costs.
Key words: infrastructure, transport, road, railway, nanotechnology.
The important increase in people and freight mobility observed in many countries results in a saturation of the infrastructures for air, rail and road transportation. During the last few years, different approaches appeared to counterbalance the negative impact of this global rise in mobility. Within this, the development of new environmental friendly, economical and ecological high-performance transport systems is vital. The Swiss metro Maglev vehicle takes a leader position in this movement. The concept of Swiss metro is that of a vehicle travelling at high speed in a monodirectional underground tunnel maintained under a partial air vacuum. The infrastructure contains two parallel tunnels, one for each direction, connected by the stations to the surface transport networks. The Swiss metro passenger transport system is based on advanced technologies – such as linear electric motors and magnetic levitation – which allow it to reach speeds of over 600 km/h, guaranteeing economical energy consumption and minimum maintenance, whilst ensuring maximum passenger safety and comfort.
On the other side, the implementation of nanotechnology in many applied fields is receiving widespread attention. It is important to ensure that these applications address real questions to allow the technology to improve general well-being of the public, especially when evaluating application in the area of civil engineering. This chapter focuses on the specific applications of nanotechnology in the field of road pavements. The main objectives of pavements are to provide a safe and durable surface on which vehicles can travel, while protecting the underlying layers of material during all environmental conditions. As such, pavements are thus exposed to two main types of loads, namely traffic and the environment. In spite of the fact that good pavements can be constructed using existing materials and techniques, there are a number of areas where the judicious application of nanotechnology techniques should be able to improve the longevity and performance of the service provided by the pavement facility. These include improved and smart materials and characterization of materials. In this research the specific current needs that are addressed through these applications are discussed.
Having all information using comparative analysis and indicators, we are closer to define the ecologically harmless type of transport and what are the future expectations that could be implemented in both sectors.
Along with the increase of population and expansion in living zones, automobiles and air services cannot afford mass transit anymore. Accordingly, demands for innovative means of public transportation have increased. In order to appropriately serve the public, such a new-generation transportation system must meet certain requirements such as rapidity, reliability, and safety. In addition, it should be convenient, environment-friendly, low maintenance, compact, light-weight, unattained, and suited to mass-transportation. The magnetic levitation (Maglev) train is one of the best candidates to satisfy those requirements. While a conventional train drives forward by using friction between wheels and rails, the Maglev train replaces wheels by electromagnets and levitates on the guideway, producing propulsion force electromechanically without any contact.
The Maglev train offers numerous advantages over the conventional wheel-on-rail system:
1) elimination of wheel and track wear providing a consequent reduction in maintenance costs;
2) distributed weight-load reduces the construction costs of the guideway;
3) owing to its guideway, a Maglev train will never be derailed;
4) the lack of wheels removes much noise and vibration;
5) noncontact system prevents it from slipping and sliding in operation;
6) achieves higher grades and curves in a smaller radius;
7) accomplishes acceleration and deceleration quickly;
8) makes it possible to eliminate gear, coupling, axles, bearings.
2.1 LESS TRAVEL TIME/ MINIMAL HASSLE
In comparison to airplanes, Maglev trains are actually slower, but they still save time due to the minimal hassle it takes to travel in them. With air travel, people still have to take into consideration the time they have to spend at the airports for security, boarding and luggage checking. All this will not be needed for traveling in Maglev trains and so the commute time will still be less.
Maglev trains are designed so they can never derail. They contain systems to always make sure the train is always kept balanced on top of the tracks and never shift off of it. Maglev trains system is also designed to never have accidents with other vehicles. The guideways are kept secured so no foreign vehicles such as cars or trucks can cross them. The system also protects trains from each other. Maglev trains travelling in opposite directions are always on different guideways, so there is never a possibility of head on collisions. And during operation, current is only provided to the part of the track where the trains are located at that specific time. This way they can check to make sure that trains never get to close to each other to have a back end collision. So far, It was never reported collision accident of a maglev train.
2.3 ENVIRONMENTALLY FRIENDLY
Maglev trains are extremely environmentally friendly as they have zero carbon emissions, since they run on electricity. Maglev trains reduce noise pollution compared to usual trains.
2.4 ALL WEATHER CONDITIONS
Another positive side of implementing Maglev trains is that they operate punctually in all weather conditions. Airplanes are constantly delayed for long hours or cancelled during storms and it is nearly impossible to drive in such weather conditions and not get stuck in severe traffic. Trains are not as bad usually, but they still get delayed during bad weather conditions such as heavy snow fall. With Maglev trains, since there is no contact with the tracks, they are functional during any weather condition and will never be delayed.
2.5 DESCRIPTION OF MAGLEV SYSTEM
Maglev, or magnetic levitation, is a transportation system that uses magnets in order to lift and push the train along a guideway. There multiple different variations of the Maglev system based on the propulsion system, levitation system, and type of magnets. Propulsion systems include the linear induction motor and linear synchronous motor. Levitation systems include electromagnetic suspension (EMS), electrodynamic suspension (EDS), permanent and superconducting magnet electrodynamic suspension. The different magnets used for the Maglev are permanent magnets, electromagnets, and superconducting magnets.
2.5.1 ELECTROMAGNETIC SUSPENSION
Electromagnets on the track use alternating current to attract the train above the guideway. The guideway electromagnets ‘attraction pulls the train 10mm above the track. The small air gap allows for decent levitation at low speeds, but at high speeds the air gap must be heavily monitored, so this system requires many sensors and control systems to maintain the required air gap. The EMS systems also have the capacity of stabilizing the train about the guideway, but that is not ideal for high speeds.
2.5.2 ELECTRODYNAMIC SUSPENSION
Unlike the EMS, the EDS places the train car in a U-shaped guideway, so that it sits inside the rail. This system capable of using permanent magnets, electromagnets, and superconducting magnets. These different magnets are placed on the guideway to repel the train above the track. The air gap produced by the magnets is significantly larger than the air gap produced by the EMS system; with an air gap of 100mm. EDS systems also are beneficial because extra control systems are not required because the levitation is controlled by permanent magnets. Even if the system uses electromagnets or superconducting magnets, the EDS system still show a higher stability than an EMS system. The only issue surrounding EDS systems is that they are unable to levitate under static conditions (no movement), so Maglevs with an EDS systems require rubber wheels for low speed travel.
The Maglev train receives its propulsion force from a linear motor, which is different from a conventional rotary motor; it does not use the mechanical coupling for the rectilinear movement. Therefore, its structure is simple and robust as compared with the rotary motor. It is a conventional rotary motor whose stator, rotor and windings have been cut open, flattened, and placed on the guideway. Even though the operating principle is exactly the same as the rotary motor, the linear motor has a finite length of a primary or secondary part and it causes “end effect”. Moreover, the large air gap lowers the efficiency. However, the linear motor is superior to the rotary motor in the case of rectilinear motion, because of the less significant amount of vibration and noise that are generated directly from the mechanical contact of components such as the screw, chain and gearbox.
Concept of the linear motor derived from the rotary motor
The two types of propulsion systems LIM and LSM are similar, since they are linear motors, but they each have their advantages and disadvantages. LIM (linear induction motors) use the concept of induced EMF coming from the guideway that produces an eddy current in the undercarriage of the train to produce a force (Lorentz force) that pushes the train down the guideway. Two different types of LIM systems include the short primary type and long primary type. The long primary type is more expensive to construct, but can achieve higher speeds that the short primary type. The LSM (linear synchronous motor) is different from the LIM because there is a magnetic source within itself. Using LSM the Maglev speed can be controlled by the controller’s frequency of the current. There are currently two types of LMS that are used in today’s Maglevs, the electromagents with iron-core and the superconducting magnets with air-core. This LSM is popular with Maglev trains because they have a higher efficiency and power factor than the LIM systems.
Linear synchronous motor
Linear induction motor (LP type).
The ultimate goal is to make the Maglev train system as cost and energy effective as possible. There are many components of a Maglev system. The project observes only the components that will affect the effectiveness of the entire system, which also accounts for the economic costs. Therefore, the system can be broken down into four major components; propulsion, levitation, station stops, and guideway type. The propulsion and levitation systems have a direct impact on the costs. The EDS type with superconducting electromagnets requires an additional cooling source, which vastly increases energy consumption, thereby costing more. The additional coolant system will also require more maintenance, which proportionally increases the overall cost. The station stops will affect the speed of the train, because depending on the distances, the train will not be able to reach maximum speeds. Increasing the number of stops increases the overall travel time, but increases the amount of money generated by the Maglev system (due to an increase in the number of passengers that could potentially be serviced).
The concept of Swiss metro is that of a vehicle travelling at high speed in a monodirectional underground tunnel maintained under a partial air vacuum. The infrastructure contains two parallel tunnels (one for each direction) connected by the stations to the surface transport networks. The Swiss metro passenger transport system is based on advanced technologies – such as linear electric motors and magnetic levitation – which allow it to reach speeds of over 600 km/h, providing economical energy consumption and minimum maintenance, at the same tine ensuring maximum passenger safety and comfort. The research deals with a general overview of the Swiss metro passenger transport system and describes the present situation in terms of industrial development, market opportunities, pilot track, costs and time frame. It also shows how Swiss metro could become an alternative to the classical High-Speed technologies.
3.1 THE SWISSMETRO TECHNOLOGY
The Swiss metro system is based on the application of four complementary technologies:
• an entirely underground infrastructure, comprising two tunnels of about 5 m interior diameter, one for each direction;
• a reduction of air pressure in the tunnels in order to diminish the energy consumption for propulsion of the pressurized vehicles;
• a vehicle propulsion system using linear electric motors, allowing speeds of over 600 km/h;
center262255• a magnetic levitation and guidance system, avoiding direct contact and friction with the track.
Vehicle and tunnel cross-section
3.1.1 ENTIRELY UNDERGROUND INFRASTRACTURE
The underground solution has many advantages:
• it is ideal for protecting the environment and avoiding the generation of noise, vibration, pollution and damage to the landscape;
• there is ease of penetration to the city centers;
• topographical conditions have little effect on construction;
• climatic conditions do not influence the movement of vehicles;
• the use of two separate tunnels, one for each direction, makes collision between two vehicles impossible.
3.1.2 PARTIAL AIR VACUUM
In proposing a vacuum level of about 1/10th of the atmospheric pressure and a small tunnel diameter, an effort was made to strike a compromise between investment costs (small diameter and pressure level as close as possible to atmospheric pressure) and operating costs (minimum energy consumption), while at the same time providing for safety, heat accumulation, construction aspects and other criteria. The retained air pressure level in the tunnels corresponds to pressure at about 15,000 m, the altitude at which Concorde flies. The partial vacuum is created by two vacuum pumps of 300 kW placed every 15 km of double tunnels.
3.1.3 PROPULSION BY LINEAR ELECTRIC MOTORS
The use of linear electric motors allows a frictionless propulsion system. The mechanical constraints, volume and maintenance are reduced. As compared to the electric locomotive with a rotary engine, the linear motor does away with the overhead power line and pantograph arm. Without these elements, the tunnel diameter can also be reduced.
3.1.4 MAGNETIC LEVITATION AND GUIDANCE SYSTEMS
Only magnetic levitation can provide economical and safe guidance at speeds in excess of 350 km/h. It eliminates all wear-and-tear, which results in considerable savings on maintenance and equipment renewal costs. The mechanical stress of the structures is also reduced and the meaningful advantage is that magnetic levitation and guidance generate practically no noise.
The Swiss metro vehicle, today on a design phase, should offers very high performances:
• very low energy costs, as little as half those of a conventional intercity train;
• a maximum speed of over 600 km/h; such a speed is sufficient for sections less than 100 km long, as is the case in the Swiss network; a higher speed can be reached by enlarging the tunnel diameter;
• a frequency of 6 to 10 vehicles per hour and per direction;
• stations designed to keep traveler waiting times to a minimum;
• a high safety level for passengers;
• operation of the system in close co-operation with the local railways and urban transport companies.
With a vehicle carrying 400 seated people every 6 minutes at rush hours, Swissmetro has a transport capacity of 4,000 travelers an hour in each direction, and this capacity could be even further increased by lengthening the vehicles or allowing the transport of standing passengers. Vehicles stop only 3 minutes at stations.
NANOTECHNOLOGY IN ROAD SECTOR
Nanotechnology has been explored to a considerable degree to address the problems in design, construction, and utilization of functional structures with at least one characteristic dimension measured in nanometers. The National Nanotechnology Initiative stipulates that Nanotechnology involves research and technology development at the atomic, molecular, or macromolecular levels, the length scale of approximately 1 to 100 nm (nanometer) range, to provide a fundamental understanding of phenomena and materials at the nano-scale and to create and use structures, devices, and systems that have novel properties and functions because of their small and/ or intermediate size. Nanotechnology therefore allows the design of systems with high functional density, high sensitivity, special surface effects, large surface area, high strain resistance, and catalytic effects. All attributes are directly or indirectly the result of the small dimensions of nano-particles. In spite of the fact that bituminous materials, such as asphalt, are mainly used on a large scale and in huge quantities for road construction, the macroscopic mechanical behavior of these materials still depends to a great extent on microstructure and physical properties on a micro- and nano-scale.
The ability of nanotechnology to constantly monitor materials could offer better prediction of service life and life cycle performance of the road. During construction, nanotechnology could allow for embedding increasingly small sensors throughout a structure or pavement. These sensors could be used for long-term monitoring of corrosion and could offer an invaluable tool in monitoring deterioration and cracking in concrete without physical intervention. Similarly, these sensors could monitor vibrations and loads on bridges and enable researchers to assess weaknesses and fix them long before they are apparent to human inspectors.
It is established that through the application of nanotechnology, the potential for improvements in the engineering properties of constituent materials of hot mix asphalt (HMA) is significant particularly, in resistance to moisture damage, strength and longevity. The ability to target material modifications at the nano level promises the optimization of material behavior and significantly improves mechanical properties of pavements like, durability, skid resistance, binding properties, maintenance and sustainability etc. It has also been experimented that nanoscale which could significantly increase the flexural strength. However, dispersion of nanotubes in cementitious materials remains a major challenge and various processing methods are being explored to optimize the number of nanotubes and their dispersion, which would help to develop cost-effective concrete for the next generation of highways.
Self-sensing nanotechnology composite material has been developed, to provide real-time information on traffic flow sand to monitor stress applications on highways, like vehicular loadings etc. The monitoring of vehicle weights is more convenient and effective as the weighing is performed while the vehicle is moving on the highway. In this way, traffic is not affected and time is saved. Apart from detecting traffic flow and monitoring loads, the self-sensing capability of the nano composite to detect stress levels is also finding applications in monitoring the health of structures. Deformation in the structure is registered as a change in the electrical resistance which is remotely monitored. Several environmental applications of nanotechnology in highways have also been reported from the developed countries. One example is the ability to monitor mobile source pollutants during construction and operations by using nanoscale devices. Low-cost environmental sensors are being used to monitor the air, water and soil quality and mapping the pollution levels.
Nanoclay is clay that can be modified to make the clay compatible with organic monomers and polymers. These nano-composites consist of a blend of one or more polymers with layered silicates that have a layer thickness in the order of one nm and a very high aspect ratio. Common clays are naturally occurring minerals and subject to natural variation in their formation. Separation of clay discs from each other results in a nano-clay with a large active surface area (up to 700-800 m2/g). This results in an intensive interaction between the nanoclay and the bitumen. While the stiffness and viscosity of specific bitumen were not affected by the addition of one specific type of montmorillonite nano-clay, another type of montmorillonite nano-clay did affect stiffness and viscosity. Various physical properties (such as stiffness and tensile strength, tensile modulus, flexural strength and modulus thermal stability) of the bitumen can be enhanced when it is modified with small amounts of nano-clay, on the condition that the clay is dispersed at the nano-scopic level.
Bentonite clay (BT) and naturally changed bentonite (OBT) were utilized to strengthen and modify an asphalt binder. The modified asphalt binders were produced by melt processing under sonication and shearing stresses. The modified asphalts had a higher rutting resistance. Adding BT and OBT significantly improved the low temperature rheological properties and the resistance to cracking of asphalt. The proper selection of modified clay is essential to ensure effective penetration of the polymer into the interlayer spacing of the clay and so resulting in the desired exfoliated or intercalated product. In an intercalate structure, the organic component is inserted between the clay layers in a way that the interlayer spacing is expanded but the layers still bear a well-defined spatial relationship to each other. In an exfoliated structure the layers of the clay have been completely separated and the individual layers are distributed throughout the organic matrix. ,
Schematic of structures of polymer nanocomposites
4.2 CARBON NANOTUBES
A CNT is a one-atom thick sheet of graphite rolled up into a seamless hollow cylinder with a diameter of the order of one nanometer. CNTs are characterized by superior mechanical properties when compared with other construction materials. Depending on the radius of the tube, the Young’s modulus of a CNT can be as high as 1,000 GPa and the tensile strength can reach 150 GPa. Two different types of CNT exist respectively in the form of single tubes (called single-wall CNTs) and coaxial tubes (multiple-wall CNTs). Multi-wall CNTs are less expensive and easier to produce but exhibit lower strength and stiffness than single-wall CNTs. Very few studies have been conducted in the area of bituminous binders and mixtures. When CNTs are added with a sufficiently high percentage (> 1%) to base bitumen, they can significantly affect rheological properties. Using carbon nanotubes equals to 0.001 of weight bitumen in asphalt mixtures, in addition to improving asphalt pavement properties, will decrease thickness of under layers and as a result reduce stone materials consumption. CNTs provide an enhancement of rutting resistance potential and of resistance to thermal cracking. Moreover, susceptibility to oxidative aging is reduced with further advantages that are expected in the long-term performance of bituminous mixtures.
Silica nanoparticles have been used in the industry to reinforce the elastomers as a rheological solute and cement concrete mixtures. Silica nanocomposites have been attracting some scientific interest as well. The advantage of these nanomaterials resides in the low cost of production and in the high performance features. With the addition of nanosilica in the base asphalt binder, the viscosity values of nanomodified asphalt binder decreased slightly. Lower viscosity of the binder indicates that a lower compaction temperature or lower energy consumption of the construction process will be achieved. The addition of nanosilica into the control asphalt improved the recovery ability of asphalt binders. The low-temperature grade of nanosilica modified asphalt binder was the same as the control asphalt binder, and the properties and stress relaxation capacity of nanosilica modified asphalt binder was the same as the control asphalt. The anti-aging performance and fatigue cracking performance of nanosilica modified asphalt binder and mixture were enhanced and the rutting resistance and anti-stripping property of nanosilica modified asphalt mixture were also enhanced significantly. The addition of nanosilica into the control asphalt binder did not greatly affect the low-temperature properties of asphalt binders and mixtures. The asphalt binder modified by 1% nano powdered rubber VP401 has better performance in resistance to low temperature crack and rutting, compared to other nanomaterial modified asphalt binder. Spraying TiO2 and ZnO fog to the surface of asphalt slabs show lower aging rates. The asphalt mixture modified by 5% SBS plus 2% nano-SiO2 powder can increase the physical and mechanical properties of asphalt binder and mixtures. The addition of nanoclay and carbon microfiber would improve a mixture’s moisture susceptibility in most cases under water or de-icing chemicals (NaCl, MgCl2 and CaCl2), and even freeze-thaw cycles.
4.4 BENEFITS OF NANOTECHNOLOGY IN ASPHALT MIXTURES
In general, Nanotechnology will produce benefits in two ways – by making existing products and processes more cost effective, durable and efficient and by creating entirely new products. In particular to asphalt and asphalt mixture properties, Nanotechnology has the following known benefits:
Improve the storage stability in polymer modified asphalt
Increase the resistance to UV aging
Reduce the moisture susceptibility under water, snow and deicers
Improve the properties of asphalt mixtures at low temperature
Improve the durability of asphalt pavements
Save energy and cost
Decrease maintenance requirements
4.5 CONCLUSIONS AND RECOMMENDATIONS
Adding Nanoclay in asphalts usually increases the viscosity of asphalt binders and improves the rutting and fatigue resistance of asphalt mixtures. One specific type of montmorillonite nano-clay doesn’t affect the stiffness and viscosity of asphalt binder. Applying Nanoclay can improve the aging resistance of asphalt mixes.
Polymer nano composites are one of the most exciting materials because of the nano-particle addition and nanoscale dispersion. Using Nano-particles can improve the storage stability of polymer modified asphalts.
The anti-aging performance, fatigue cracking performance, rutting resistance, and anti-stripping property of nanosilica modified asphalt binder and mixture are enhanced. Meanwhile, the addition of nanosilica into the control asphalt binder did not extremely affect the low-temperature properties of asphalt binders and mixtures.
Road transport is the most commonly used mode of transport for the movement of goods connecting customers to cargo and vice versa.
Rail transport is a commonly used mode of transport especially in countries and continents with long transit such as across China, Russia, USA and parts of Europe.
Freight trains are capable of carrying various types of cargoes such as freight containers, vehicles, livestock, commodities such as grains, coal, minerals and metals etc.
But both modes of transport have its own pros and cons. ,
Road Freight can be delivered quickly as per a set schedule Limitations such as cargo size and weights maybe applicable for road weight across various states
Cost effective and economical especially over short distances May not be a cost-effective option across longer distances
Used for long haul, short haul, local and over border movements Slower than rail over long distances
Full door to door movement Limitations due to weather and road conditions
Easier option for tracking of cargo movement through GPS and satellite tracking Not as environmentally friendly as rail
Rail Greener option for transport as trains burn less fuel per ton mile than road vehicles Additional costs to move a container from rail head to final destination, mostly using road freight.
Freight trains carry more freight at the same time compared to road transport Possible delays in cross border due to change of train operators
On average, long distance freight movement is cheaper and quicker by rail Not economically viable across shorter distances
Freight trains have proven to be transit sensitive even more than ocean freight delivering cargo from China to Europe in as less as 18 days compared to 44 days by sea Abnormal cargoes cannot be moved in normal rail wagons
5.1.1 Phase I
From the table below, it is clearly seen that for the freight and passenger transport in all countries is used the road transport. Proportionally to these results, in the third table are presented information for the road and rail investment which is clearly seen that the investments for roads are 2.7 times more than rail`s, creating a network that results in good trade which strengthens the local and international economy between countries.
Table1: Rail/Road passenger transport20320234119
27305287655Table 2: Rail/Road freight transport
730241917Table 3: Rail/Road infrastructure investment
Table 3: % of Rail/Road infrastructure from the total area of the coutry
550295225442Table 5: Rail/Road (km) per 1000 citizens
These two tables above show the results obtained using new indicators that measure the extent to which road and rail infrastructure representation is compared to the total territorial area of the countries involved in this research. The Czech Republic and France have the most significant percentage of railway infrastructure representation in relation to other countries, while the same countries have a significant high percentage in the road infrastructure as well as Finland and Sweden.
Regarding the road and railway infrastructure in km belonging to 1000 citizens of the total number of citizens in the respective countries, the results between these two sectors are drastically different between them, differing from 10-50 times higher in road infrastructure compared to the railway sector.
These results give a clear picture that in almost all countries, the road infrastructure is significantly more prevalent than the rail resulting from the large investments invested in this sector, while in the rail sector they are 2- 5 times smaller.
SMART MATERIALS FOR NEXT GENERATION INFRASTRUCTURE
The flexibility of building and civil engineering structures is typically associated with the design of individual elements such that they have sufficient capacity or potential to react in an appropriate manner to adverse events. Traditionally this has been achieved by using ‘robust’ design procedures that focus on defining safety factors for individual adverse events and providing overabundance. More recently, based on a better understanding and knowledge of microbiological systems, materials that have the ability to adapt and respond to their environment have been developed. This fundamental change has the potential to facilitate the creation of a wide range of ‘smart’ materials and intelligent structures, including both autogenous and autonomic self?healing materials and adaptable, self?sensing and self?repairing structures, which can transform our infrastructure by embedding resilience in the materials and components of these structures so that rather than being defined by individual events, they can evolve over their lifespan.
6.1 SELF HEALING INFRASTRUCTURE MATERIALS
Self-healing development in cementitious systems are broadly divided into two categories: autogenous and autonomic. Autogenous self-healing refers to self. Residual life models for concrete repairs. Biomimetic multi-scale damage immunity for concrete. Autonomic self-healing refers to actions that use components that do not naturally exist in the cementitious composite, i.e. ‘engineered’ additions that are usually employed to deal with larger crack sizes. Examples of both systems are shown schematically in the picture below. Some autogenous and autonomic self-healing systems work in combination so that the autonomic system works to reduce the crack size to enable autogenic processes to complete the self-healing.
-2540002372995The autonomic self-healing systems we have developed to date include the following: Micron size capsules that contain a healing agent. For cementitious systems the challenge is to use suitable and compatible materials for both, that will enable survivability during the mixing, effective bonding between the shell and the cementitious matrix, longevity within the matrix, appropriate rupture when intersected by a crack and adequate release of the healing agent. The healing agent in turn needs to have a long shelf-life, to effectively flow out of the fractured capsule and to be capable of forming effective sealing and healing products. The most promising developments to date have included microcapsules with polymeric, gelatin/gum Arabic or polyurea, shells and a sodium silicate. These have been developed in collaboration and have been shown to be capable of withstanding high shear mixing. Work has been carried out on size and quantity of microcapsules for different cementitious composites.
Autogenous self-healingAutonomic self-healing
6.2 CALCIUM CARBONATE- PRECIPITATING BACTERIA
The bacteria-based approach works by encapsulating bacteria spores and a calcium precursor within the material. On appearance of a crack the bacteria germinate and by metabolic actions precipitate calcium carbonate within the crack. Research has led to the creation of a bespoke combination of alkaliphilic Bacillus bacteria, nutrients and precursors that rapidly precipitate calcium carbonate and return the permeability of concrete to that prior to cracking. The first ever critical analysis of the kinetics of bacterial calcium carbonate formation demonstrated that it was possible to tailor the nutrients to maximize mineralizing capacity using a selection of microbiological aids that were compatible with concrete hydration.
6.3 SHAPE MEMORY POLYMERS
The SMP system employs pre-drawn PET tendons to close cracks in concrete structural elements. These tendons are cast into a concrete structural element and electrically activated after cracking occurs. They are anchored at discrete locations so that when they are activated, a released restrained shrinkage potential applies an internal compressive force to the structural element. This compressive force tends to close any cracks that have formed within the cementitious material. The ability of the tendons to maintain a significant post-activation crack closure force is important to the viability of the self-healing system. A series of tests explored the long-term relaxation of the restrained shrinkage stress within SMP tendons and research was undertaken to scale up this technology and develop higher performance tendons, producing a new tendon assembly that comprised multiple SMP filaments, an outer spiral wire for electrical activation and a plastic sheath for protection.
Sensors have been developed and used in construction to monitor and control the environment condition and the materials / structure performance. One advantage of these sensors is their dimension (10 – 9 m to 10 – 5 m). These sensors could be embedded into the structure during the construction process. A low cost ceramic-based multi-functional device has been applied to monitor early age concrete properties such as moisture, temperature, relative humidity and early age strength development. The sensors can also be used to monitor concrete and bitumen road corrosion and cracking. The smart aggregate can also be used for structure health monitoring. The disclosed system can monitor internal stresses, cracks and other physical forces in the structures during the structures life. It is capable of providing an early indication of the health of the structure before a failure of the structure can occur. Some of the sensors can also help to reduce sound and air pollution from road.
The trade-off analysis focuses on three system aspects: cost, speed, and safety. These performance metrics were chosen because they are the basic characteristics of a train system. Cost of train systems are always compared to one another and used as a measure of whether or not a transportation project is feasible. The cost metric takes into consideration all of the components in the Maglev system and its construction, but not the cost of purchasing land for the guideways or building station along the track. The measure for cost in the trade-off analysis is in billion dollars scale. Speed is the most common standard used to compare transportation systems and is directly related to the time needed to travel. For the Maglev, speed is an extremely appealing attribute since it can travel over a hundred miles per hour faster than the current high-speed rail. Lastly, reliability is the most crucial parameter because knowledge of a transportation system’s safety is the determining factor whether or not the system is viable. Passenger safety requires transportation reliability, which is paramount to all other system aspects. But testing and measuring how reliable a transportation system can become highly complex.
While nano-materials are making roads into certain construction applications in pavements and highway structures, many difficulties remain in the path of widespread adoption of this technology due to the conservative nature of contractors and high expectations of consumers. In addition, material and manufacturing costs are an issue in cost sensitive, large volume applications while concerns over health and safety are also yet to be proved.
On the margins of functionality and technological development, as well as the application and representation of the road and rail sector, it can be said that these two sectors are developing in parallel. The application of nanotechnology on the one hand and the fast trains on the other side promise improvement of their infrastructure, but still some of the theses and examinations are not fully applicable. As the results of the comparative analysis using primary and secondary sources have shown, road traffic is most common in all countries taken in this research with a proportional investment item due to their accessibility and the transport network they own. The positive side tended towards rail traffic is mostly from an environmental point of view using underground railways and electromagnetic fields for the movement of high-speed trains, while nanotechnology roads are still unknow to the environment. In the future, road traffic will still have a high percentage of representation, but the speed of the Maglev and the Swiss metro trains will become competitive to air transport.
Review of Maglev Train Technologies “Korea Railroad Research Institute, Uiwang 437-757”, “Korea
Department of Electrical Engineering”, Hanyang University, Seoul 133-791, Korea
2 https://science.howstuffworks.com/transport/engines-equipment/maglev-train.htm3 https://www.quora.com/How-do-magnetic-levitation-trains-work4 Swissmetro: a revolution in the high-speed passenger transport systems Michele Mossi, GESTE Engineering SA, Lausanne Pierre Rossel, EPFL-ESST, Lausanne Conference paper STRC 2001 Session Concepts
5 http://www.swissmetro.com/6 Modernized but still integrated: The Swiss Federal Railways on the path towards the future (1950s to 2000)1 Gisela Huerlimann Research Center for Social and Economic History at the University of Zurich
7 https://www.maglevboard.net/en/8 Nanotechnology in Civil Engineering, V Kartik Ganesh, Department of Civil Engineering, SRM University Kattankulathur, Chennai-603203, INDIA
11 13th COTA International Conference of Transportation Professionals (CICTP 2013) A review of advances of Nanotechnology in asphalt mixtures Jun Yanga,b,* Susan Tigheb a School of Transporation, Southeast University, Nanjing, 210096, P.R. China b Civil Engineering ; Environmental Department, University of Waterloo, Waterloo, N2L 3G1, Canada
12 NANOTECHNOLOGY SYNTHESIS STUDY-RESEARCH REPORT, Project performed in cooperation with the Texas Department of Transportation and the Federal Highway Administration.
14 Overview of Nanotechnology in Road Engineering Arpit Singh1,*, Dr. Sangita1, Arpan Singh2 1 CSIR-CRRI, Delhi Mathura Road, New Delhi, 110020 India 2 Northern India Engineering College, Shastri Park, New Delhi, 110053 India (Received 01 February 2015; published online 10 June 2015)