It is a component of permanent way laid transversely under the rails and performing the following functions.
To support the rails firmly and evenly
To maintain the gauge of the back correctly
To distribute the weight common on the rails over a sufficiently large areas of the ballast
To act as an elastic medium between the rail and the ballast and to absorb the vibrations of the trains.
To maintain the track at proper grads
To align the rail properly
2. Characteristics of Ideal Railway Sleepers
Initial cost and maintenance cost should be low
They should resist weathering, corrosion, decay and other deterioration
They should bear the wheel load efficiently and satisfactorily
They should maintain the correct gauge
They should absorb shocks or vibrations due to moving vehicles
It should distribute the load properly and uniformly over the ballast
Fastenings of rail with sleepers should be strong and simple
They should not break while packing of ballast
Weight should not be low or high
3. Types of Railway Sleepers
Depending upon the position in a railway track, sleepers may be classified as:
1. Longitudinal Sleepers
2. Transverse Sleepers
i. Timber / wooden sleepers
ii. Steel Sleepers
iii. Cast Iron Sleepers
iv. Concrete Sleepers
4. Treatment of Wooden Sleepers
Untreated railway sleepers are prone to attack by decay and vermin. The life of untreated wooden sleepers is thus very less. The life of untreated sleepers can be prolonged considerably by treatment. An extra life of 30-50% is estimated for treated sleepers over untreated railway sleepers.
The fibers of wood contain millions of minute cells containing juices. When these juices ferment, they lead to decay of timber. In the treatment process these juices are removed as much as possible and cells are filled with some preserving solutions may be an oil or some salt solution.
5. Railway Sleeper Density
The number of sleepers required to be placed under the track per rail length is called as its sleepers density.
It is generally given by the formula Sleeper density = n + x
There are three distinct methods of construction of railway track. These are:
Telescopic Method
Tramline Method
Mechanical Method
1. Telescopic Method of Construction of Railway Track
In this method, rails, sleepers and fastenings are unloaded from the material train as close to the rail head as possible. The sleepers are carried by carts or men along the adjoining service road and spread on the ballast. The rails are then carried on pairs to the end of last pair of connected rails and linked.
To carry rails manually over a long distance is a tedious job. So certain carriers called Anderson rail. Carriers are used to carry rails to the ends of the rail head.
It can also take rails up to a head last pair linked with the help of temporary track consisting of 3″ x 3″ angle irons of the same length as rails and fastened to the sleepers.
A further consignment of the material is deposited at the advances rails head and the procedure is repeated.
2. Tramline Method Railway Track Construction
This method is used where tram carrier are installed for carrying earthwork or in rainy season due to difficulty in movement of cart. Some tramline is established on with a gauge of 2′-2′-6″. The basic difference between this and telescopic method lies in the conveyance and spreading of the sleepers.
The track can be assembled at more than one points simultaneously, which is the great advantage of this method. Sometimes an additional track is laid on the side of existing track for which this method is best.
3. Mechanical Method Railway Track Construction
This method is extensively used in Britain and America by using special track laying machine. There are two types of machines available. In first type of machine, the track material carried by the material. Train is delivered at the rail head and laid in the required position by means of projecting arm or mounted on the truck nearest to the rail head. The material train moves forward on the assembled track and operation is repeated.
In the second type of machines a long cantilevered arm projecting beyond. The wagon on which is fitted. A panel of assembled track consists of pair of rail with appropriate number of sleepers on the ballast layer. This panel is conveyed by special trolley running over the wagons of material train to the jibs. It is lowered by the jib in the required position and connected to the previous panel. The track laying machine then movies forwarded and operation is repeated.
New Bridge Composite Twice as Strong as Concrete and Steel
The University of Maine’s Advanced Structures and Composites Center tests the strength of their new composite girders at a ceremony on July 12th. (Image courtesy of University of Maine.)
Researchers at the University of Maine have developed a lightweight composite bridge that is twice as strong as steel and concrete bridge girders.
In a mid-July demonstration, the university’s Advanced Structures and Composites Center tested a 21-foot span of the composite with computer-controlled hydraulic equipment that can simulate the weight of highway traffic. The test was necessary to ensure that the bridge passed American Association of State Highway and Transportation Officials (AASHTO) Bridge Design Specifications, and it succeeded with flying colours.
“Today’s bridge test exceeded our expectations,” said Habib Dagher, executive director of the Center. “The composite bridge withstood forces equivalent to more than 80 cars stacked on top of each other, and more than 5 times the HL 93 design load specified by AASHTO. The composite bridge girder exceeded twice the collapse strength of steel and concrete girders.”
The design is made up of lightweight composite FRP girders connected to precast concrete panels, a system which the team says can allow a bridge to be built in as little as three days. The composite is an undisclosed blend that involves thermoset resin, glass fiber and carbon fiber, which means that the girders are relatively light (approximately 1-2 tons for 40- to 80-foot spans). The lighter weight makes the bridge easier to ship, as does the “stackable” shape of the girders. To Dagher and his team, the ease of transport was an important consideration: “Our design philosophy has been to look at the entire lifecycle.”
The test came a little over a month after the US Department of Transportation announced that they would grant UMaine up to $14.2 million to lead a push to improve the durability of New England’s transportation infrastructure. And it looks like the bridge will stand up to the challenge. According to the team, the girders are designed to last for up to 100 years, and the panels are relatively easy to replace. “The unique connection system we’ve developed allows you to come in 50 years later, essentially pull the deck out and then put the new deck on without having to jackhammer the concrete deck like you typically would,” Dagher said.
The Center is also responsible for the famous Bridge-In-A-Backpack, a lightweight FRP composite structure to reinforce arch bridges. And Advanced Infrastructure Technologies, the company that licensed Bridge-in-a-Backpack, is looking forward to licencing the new composite after another round of trials in August.
“As the commercialization partner of the Center’s composite arch bridge system, today’s event allowed us to showcase this new technology with potential investors as well as DOT partners and executives,” said Brit Svoboda, chairman and CEO of AIT Bridges, on the day of the trial. “We’re ready to go to market.”
Dams can fail for one or a combination of the following reasons:
1. Overtopping caused by water spilling over the top of a dam. Overtopping of a dam is often a precursor of dam failure. National statistics show that overtopping due to inadequate spillway design, debris blockage of spillways, or settlement of the dam crest account for approximately 34% of all U.S. dam failures.
2. Foundation Defects, including settlement and slope instability, cause about 30% of all dam failures.
3. Cracking caused by movements like the natural settling of a dam.
4. Inadequate maintenance and upkeep.
5. Piping is when seepage through a dam is not properly filtered and soil particles continue to progress and form sink holes in the dam. [See an animation of a piping failure.] Another 20% of U.S. dam failures have been caused by piping (internal erosion caused by seepage). Seepage often occurs around hydraulic structures, such as pipes and spillways; through animal burrows; around roots of woody vegetation; and through cracks in dams, dam appurtenances, and dam foundations.
II. History of dam failures around the world
Here are some cases of dam failures around the world
1. Malpasset arch dam failure in France in 1959 (421 deaths)
The causes:
High uplift pressures following heavy rainfall & a weakness in the left abutment rock
Lessons learnt:
Appropriate SI and assessment by experts in all areas of dam design
2. Vaiont dam overtopping incident in Italy in 1963 (2600 deaths)
The causes:
Instability of reservoir slopes causing a landslip & 125m high wave over the dam
Lessons learnt:
Measure pore water pressures & movements at depth as well as at the surface
3. Dale Dyke dam breach in 1864 ( 244 deaths )
The causes:
Internal erosion possibly caused by hydraulic fracture of the core
Lessons learnt :
Designs include wider cores, use of cohesive & compacted fill and placing pipes in tunnels through natural ground
4. Eigiau & Coedty dam failures in 1925 (16 deaths)
The causes :
Foundation failure of Eigiau & overtopping failure of Coedty
Lessons learnt :
Dams need to be designed, supervised and inspected by qualified engineers
Slide Failure at Dam – Association of State Dam Safety Officials (ASDSO)
Cement is the basic ingredient of construction and the most widely used construction material. It is a very critical ingredient, because only cement has the ability of enhancing viscosity of concrete which in returns provides the better locking of sand and gravels together in a concrete mix.
CEMENT MANUFACTURING PROCESS PHASES
Production of cement completes after passing of raw materials from the following six phases. These are;
Raw material extraction/ Quarry
Grinding, Proportioning and Blending
Pre-heater Phase
Kiln Phase
Cooling and Final Grinding
Packing & Shipping
CEMENT MANUFACTURING PROCESS PHASE 1: RAW MATERIAL EXTRACTION
Cement uses raw materials that cover calcium, silicon, iron and aluminum. Such raw materials are limestone, clay and sand. Limestone is for calcium. It is combined with much smaller proportions of sand and clay. Sand & clay fulfill the need of silicon, iron and aluminum.
Extraction of raw material and crushing of material
Generally cement plants are fixed where the quarry of limestone is near bye. This saves the extra fuel cost and makes cement somehow economical. Raw materials are extracted from the quarry and by means of conveyor belt material is transported to the cement plant.
There are also various other raw materials used for cement manufacturing. For example shale, fly ash, mill scale and bauxite. These raw materials are directly brought from other sources because of small requirements.
Before transportation of raw materials to the cement plant, large size rocks are crushed into smaller size rocks with the help of crusher at quarry. Crusher reduces the size of large rocks to the size of gravels.
CEMENT MANUFACTURING PROCESS PHASE II: PROPORTIONING, BLENDING & GRINDING
The raw materials from quarry are now routed in plant laboratory where, they are analyzed and proper proportioning of limestone and clay are making possible before the beginning of grinding. Generally, limestone is 80% and remaining 20% is the clay.
Proportioning of raw material at cement plant laboratory
Now cement plant grind the raw mix with the help of heavy wheel type rollers and rotating table. Rotating table rotates continuously under the roller and brought the raw mix in contact with the roller. Roller crushes the material to a fine powder and finishes the job. Raw mix is stored in a pre-homogenization pile after grinding raw mix to fine powder.
CEMENT MANUFACTURING PROCESS PHASE III: PRE-HEATING RAW MATERIAL
After final grinding, the material is ready to face the pre-heating chamber. Pre-heater chamber consists of series of vertical cyclone from where the raw material passes before facing the kiln. Pre-heating chamber utilizes the emitting hot gases from kiln. Pre-heating of the material saves the energy and make plant environmental friendly.
Preheating of raw material | Vertical cyclone
CEMENT MANUFACTURING PROCESS PHASE IV: KILN PHASE
Kiln is a huge rotating furnace also called as the heart of cement making process. Here, raw material is heated up to 1450 ⁰C. This temperature begins a chemical reaction so called decarbonation. In this reaction material (like limestone) releases the carbon dioxide. High temperature of kiln makes slurry of the material.
Rotary kiln
The series of chemical reactions between calcium and silicon dioxide compounds form the primary constituents of cement i.e., calcium silicate. Kiln is heating up from the exit side by the use of natural gas and coal. When material reaches the lower part of the kiln, it forms the shape of clinker.
CEMENT MANUFACTURING PROCESS PHASE V: COOLING AND FINAL GRINDING
After passing out from the kiln, clinkers are cooled by mean of forced air. Clinker released the absorb heat and cool down to lower temperature. Released heat by clinker is reused by recirculating it back to the kiln. This too saves energy.
Clinker cooling | Cement making process
Final process of 5th phase is the final grinding. There is a horizontal filled with steel balls. Clinker reach in this rotating drum after cooling. Here, steel balls tumble and crush the clinker into a very fine powder. This fine powder is considered as cement. During grinding gypsum is also added to the mix in small percentage that controls the setting of cement.
Rotating ball mill
CEMENT MANUFACTURING PROCESS PHASE VI: PACKING AND SHIPPING
Transportation of cement from silos
Material is directly conveyed to the silos (silos are the large storage tanks of cement) from the grinding mills. Further, it is packed to about 20-40 kg bags. Only a small percent of cement is packed in the bags only for those customers whom need is very small. The remaining cement is shipped in bulk quantities by mean of trucks, rails or ships.
CEMENT MANUFACTURING PROCESS FLOW CHART
After explaining the complete process of cement making, flow chart would be like that. flow chart present the summary of whole process as shown below.
There are a lot of quotes related to civil engineering on the internet. We have gathered together all the inspirational, funny, motivating, interesting quotes related to civil engineering here. You will get all the best civil engineering quotes in the following list.
Inspirational Famous Civil Engineering Quotes
The followings are the inspirational quotes for civil engineers.
We shape our buildings, thereafter they shape us.
There can be little doubt that in many ways the story of bridge building is the story of civilisation. By it we can readily measure an important part of a people’s progress.
When engineers and quantity surveyors discuss aesthetics and architects study what cranes do we are on the right road.
This is not the age of pamphleteers. It is the age of engineers. The spark-gap is mightier than the pen. Democracy will not be salvaged by men who talk fluently, debate forcefully and quote aptly.
The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong, it usually turns out to be impossible to get at and repair.
The joy of engineering is to find a straight line on a double logarithmic diagram.
One has to watch out for engineers – they begin with the sewing machine and end up with the atomic bomb.
Nothing is so inspiring as seeing big works well laid out and planned and a real engineering organisation.
Nothing can be of great worth or holy which is the work of builders and mechanics.
No greater care is required upon any works than upon such as are to withstand the action of water; for this reason, all parts of the work need to be done exactly according to the rules of the art which all workmen know, but few observe.
Men build bridges and throw railroads across deserts, and yet they contend successfully that the job of sewing on a button is beyond them. Accordingly, they don’t have to sew buttons.
It takes an engineer to undertake the training of an engineer and not, as often happens, a theoretical engineer who is clever on a blackboard with mathematical formulae but useless as far as production is concerned.
His father loved him dearly, but his work, that of a civil engineer, had left him with but little time for his family. Energetic, active, and always taken up with some responsible work, he did not spoil his children with excessive tenderness.
Go for civil engineering, because civil engineering is the branch of engineering which teaches you the most about managing people. Managing people is a skill which is very, very useful and applies almost regardless of what you do.
From the laying out of a line of a tunnel to its final completion, the work may be either a series of experiments made at the expense of the proprietors of the project, or a series of judicious applications of the results of previous experience.
Engineers … are not mere technicians and should not approve or lend their name to any project that does not promise to be beneficent to man and the advancement of civilization
Engineering refers to the practice of organizing the design and construction [and, I would add operation] of any artifice which transforms the physical world around us to meet some recognized need.
Engineering is the art of modelling materials we do not wholly understand, into shapes we cannot precisely analyse so as to withstand forces we cannot properly assess, in such a way that the public has no reason to suspect the extent of our ignorance.
Architects and engineers are among the most fortunate of men since they build their own monuments with public consent, public approval and often public money.
A great bridge is a great monument which should serve to make known the splendour and genius of a nation; one should not occupy oneself with efforts to perfect it architecturally, for taste is always susceptible to change, but to conserve always in its form and decoration the character of solidity which is proper.
A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible
A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.
Scientists dream about doing great things. Engineers do them.
Scientists investigate that which already is; Engineers create that which has never been.
Each type of knowledge has value; however, from an engineering point of view, practical knowledge seems to be more valuable than theoretical knowledge.
Funny Civil Engineering Quotes
An engineer is someone who is good with figures, but doesn’t have the personality of an accountant.
Life is like a gas turbine, After every compressor, there is always a turbine!;
Engineering is the art and science of nuts and bolts.
Interesting Civil Engineering Quotes
“One man’s “magic” is another man’s engineering. “Supernatural” is a null word.”
In engineering, the joints are the most crucial. They have to be both firm and flexible, exactly like the joints in our body.;
Earlier this month, Russian President Vladimir Putin got behind the wheel of a bright orange dump truck and led a convoy across the Crimea Bridge, a new bridge that links Russia to the Crimean Peninsula. The bridge, which stretches12 miles across the Kerch Strait, is now Europe’s longest bridge.
But media coverage of the bridge hasn’t focused on its length, or any of its physical properties. That’s because the new bridge connects Russia to territory it annexed from the Ukraine in 2014—an action Western governments have called illegal. To many observers, especially those in the Ukraine, the bridge was a political power move, designed to seal Russia’s hold on the region.
While the politics of the bridge are complicated, its engineering is fascinating. A bridge across the Kerch Strait has been under consideration for more than a century, but has been blocked by brutal geological and environmental conditions. Experts in the area aren’t sure how long the bridge will stand.
History
The first Russian plans for the bridge were put forward by Tsar Nicholas II in 1903, but were then sidelined by wars and economic concerns soon afterward. German engineer Albert Speer picked up the idea for the bridge in 1943, envisioning that it would aid in the Nazi takeover of Soviet Russia. Bridge construction started that year, but was halted by Soviet attacks, and much of the remaining bridge was blown up by the German army during its retreat from the region.
The next year, the Soviet Army used the leftover building materials to build a single-track railway bridge across the strait for the wartime Yalta Conference. Part of the conference delegation managed to take the train across the bridge, but seasonal ice floes took out several of the structure’s supports in early 1945, and the bridge was not repaired. More permanent plans were put on hold due to the cost of the project and the difficult building conditions across the strait.
After the Soviet Union collapsed, politics became yet another barrier to bridge building. In 1954, Soviet Russia had transferred control of the Crimean Peninsula to Soviet Ukraine, so Russia no longer had control of Crimea when the USSR disbanded. Proposed projects in the 1990s and 2000s collapsed, but in 2010, the two countries finally signed an agreement to build a bridge together.
But Russia’s annexation of Crimea in 2014 severely strained relations between the two countries. The Ukraine imposed sanctions on Crimea, effectively cutting off most of its trade and forcing it to conduct trade across the strait with Russia by ferry. These sanctions made goods expensive in Crimea, as well as limited the number of Russia tourists crossing the strait to vacation there. So, in 2015, Putin announced that Russia would build a bridge to the peninsula on its own.
Building Bridges
In early 2015, the Russian government awarded the 228billion-ruble ($3.7 billion) bridge contract to infrastructure construction firm Stroygazmontazh Ltd. (SGM), a company that specialized in pipelines but which had not previously built any major bridges. The risk of international sanctions made it difficult to attract foreign investment or obtain insurance to cover the project, and SGM eventually used a small Crimean insurance company to underwrite a potential $3 billion loss.
The physical environment also presented several barriers to bridge construction. The site’s historic significance briefly worked against the project: divers searching the sea floor in preparation for the construction found over 200 bombs and a downed WWII-era plane. The weather also posed problems in the early stages of the project. Leonid Ryzhenkin, the project’s construction director, told NPR in 2016 that poor weather had interfered with the work, making it impossible for construction vessels to leave port. To limit weather disruption, SGM put up three temporary bridges to transport workers, supplies and heavy machinery like mobile cranes and piling rigs to the build sites.
Despite these disruptions, the project was finished ahead of schedule. And while officials projected that the road portion of the bridge would be finished by the end of 2018, it’s already open to light traffic.
The finished road bridge has four lanes, with a two-lane railroad bridge planned for the end of 2019. It stretches from the town of Taman in Russia to the city of Kerch on the Crimean Peninsula, passing through Tuzla Island along the way. It covers 4 miles of open water between Taman and Tuzla, 4 miles across the sandy island, and 3.4 more miles of water from Tuzla to Crimea.
Composite satellite image of the completed bridge, stretching from the Crimean Peninsula (left) to Russia’s Taman Peninsula (right). Approximately one-third of the bridge passes over Tuzla, an island that legally belongs to Crimea (Image courtesy of Google Maps.)
Between Tuzla and Crimea, there is a 745-foot double shipping channel arch, with one arch on the road bridge and one on the forthcoming rail bridge. Both arches have a 115-foot clearance for boats to pass underneath. The arches were built on land and towed out to sea by boat.
The road bridge is completed, and the rail bridge is on track to be finished soon. International disapproval hasn’t stopped the project’s construction—or even slowed it. But while the political and economic challenges facing the bridge have largely been overcome, there are other possible threats lurking under the waterline.
Shaky Ground
The Kerch Strait is known to be geologically unstable. A tectonic fault passes through the ocean floor under the strait, and the bedrock is covered in a layer of silt up to 197 feet thick that must be dug through to get a stable foundation. Further complicating matters is that the strait’s seismic activity can make mud volcanoes from the silt. Mud volcanoes are formed when water heated deep in the Earth’s crust mixes with underground mineral deposits, and the mixture is forced upward through a geological fault. As of 2010, Ukraine’s Department of Marine Geology and Sedimentary Ore Formation reported almost 70 mud volcanoes found in the Azov-Black Sea Basin where the Kerch Strait is located.
The bridge is supported by over 7,000 piles of three different varieties: bored piles (reinforced concrete piles poured into depressions on-site), prismatic piles (blunt, wedge-shaped supports), and tubular steel piles. These piles were driven up to 300 feet below water level because of concerns about stability.
The site’s tubular pillars are arranged in a fan shape, with many of the supports set at an angle, making the bridge more stable in case of seismic activity.
But not everyone thinks these measures will be enough to keep the bridge steady on its perilous ground. Civil engineer Georgy Rosnovsky, who previously designed two other possible versions of the Kerch Bridge, is troubled by the current design. He believes that the bridge is necessary, but has stated that he thinks it’s being built “in the wrong place and the wrong way.” He believes the pilings need to be at least 100 meters (328 feet) long, and worries that they are not sunk deep enough into the bedrock to be stable.
Rosnovsky also thinks that the bridge’s spans (the distance between supports) aren’t long to allow ice floes through. He planned his 1993 bridge with spans of 230-660 meters (755-2,170 feet), but said that any spans over 200 meters would be safe from ice. The current design’s longest span is 227 meters, but most of the spans are much shorter than that. According to Rosnovsky, this design puts the bridge at risk of suffering the same fate as the temporary bridge that was destroyed by ice floes in 1945.
Yuri Medovar, of the Russian Academy of Sciences, is another critic of the bridge. Talking to news agency Sotavision in late 2016, Medovar expressed concern that the area hadn’t been sufficiently mapped, and that the complex geology and weather conditions would make the structure risky. He warned of the costs of poorly built bridges, citing the 2013 bridge collapse in Borisoglebsk that killed two people. “You can build everything, ” he concluded, “but how much it will cost, and how [long will it] stand?”
Despite the difficult building conditions, the bridge’s creators aren’t worried about the possibility of collapse. “It will stay intact for 100 years, Rotenberg said in an interview with the Itogi Nedeli weekly news roundup after the bridge’s inaugural drive. “At least. We guarantee that. Everything is done perfectly well.” But critics like Rosenberg aren’t satisfied. “It’s a rich firm, but it’s not built by experts. They think that money is everything,” Rosnovsky told FOCUS in 2016. “The bridges are built from the calculation of the service life of a hundred years, but I think that this bridge will be short-lived.”
Building Information Modelling (BIM) is being used to help deliver large scale water projects more efficiently, economically and more quickly. In this article consultancy Atkins explains why it is a key part of the digital revolution and how it was used to deliver the £150 million expansion programme at United Utilities’ Liverpool Wastewater Treatment Works.
As we move towards a digital revolution for our buildings and infrastructure, information is playing an increasingly significant role. Building Information Modelling (BIM) is an important step towards realising this vision – redefining and challenging how we deliver projects in our industry, changing everything from the tools we use, the skills we require and our relationships with clients.
BIM enables teams to work together on infrastructure to predict its performance before it’s actually built. By fully understanding how infrastructure will work at the design stage through analysis, simulation and visualisation, better decisions can be made.
Treating waste in Liverpool
BIM is delivering multiple benefits for utility United Utilities at Liverpool Wastewater Treatment Works, a £150 million expansion programme where consultancy Atkins is working in a joint venture partnership with Galliford Try and Costain (GCAJV). The finished project will serve the needs of more than 600,000 people and have the capacity to deal with 960,000 m3/day. Specifically set up to deliver detailed design and construction for United Utilities Asset Management Programmes, the joint venture has been in partnership with the company for over 12 years.
Atkins was responsible for the detailed design of a 16-cell, two-level sequence batch reactor (SBR), complete with pumping station, sludge treatment plant, distribution chambers, blower building and control centre. The facility has been constructed inside the previously operational Wellington Dock, adjacent to UU’s existing Sandon Dock Treatment Works.
Implementing a BIM strategy to deliver a 3D model to act as a ‘single source of truth’ and the core of the design process promoted a culture of collaboration and integration. The project team had the freedom to explore alternative concepts, conduct value engineering, optimise designs, and plan and rehearse construction. Designers, constructors, process partners, supply chain and client behaved far more efficiently than ever, which led to improved cost-effective coordination, buildability, operability and maintainablility.
The federated model of the entire new build brought together over 400 individual models from all disciplines and the supply chain. This showed the value of having a virtual model to highlight opportunities for change, leading to quick and easy comment and sign off. Value-engineered design improvements could also be communicated to the client more effectively.
For example, the 3D model was also used to explain how raising part of the basement level in the pumping station would greatly reduce the size of the cofferdam and decrease the amount of concrete required. In practical terms, the use of BIM optimised the internal flooring, improving access to equipment and enhancing safety. It also highlights the extent to which waste can be reduced in the design phase.
Although BIM has been evolving for over 40 years, only relatively recently has software been capable of producing 4D timeline tools to plan and track various stages in a building’s lifecycle, from concept to construction.
The granularity of the model ensured it could be aligned to the construction programme, facilitating 4D timelining to monitor progress, and planning construction activities to avoid clashes in the schedule. Costs and embedded carbon were also added to give the team a complete picture of the work in progress.
BIM station drives collaboration
A BIM station was set up in the common area of the site offices. Site personnel were able to navigate around the model to their designated work areas and check for safety concerns and access routes, or simply orientate themselves within the structure and ongoing construction areas.
Client operatives visited the station to view a facility that would not be handed over to them for at least another 12 to 18 months, but gave them the chance to offer feedback to aid design. The model was also used by the safety, health and environment department to aid inductions, tool box talks and risk assessments.
Feeding discipline-specific applications into the model, and providing an informed work environment to support the design and documentation process reduced errors, and helped deliver the project on time and under budget.
Enhanced safety
Visualising infrastructure while it is being built is another advantage of BIM, and health and safety reviews are far more effective because a model is easier to interpret than a series of 2D drawings. So in the context of Liverpool, the model was used to show operatives the damage that would occur to the large diameter steel pipe if it was cut on-site using hand tools.
BIM technology enables teams to build the infrastructure twice; once, virtually, and the second time for installation. With greater collaboration comes greater accuracy and fewer design corrections. For example, clash avoidance minimised the risk of expensive and time-consuming re-work, with the model synchronised periodically to ensure all elements are compatible. These benefits extend to the build phase, where fewer alterations also saves time and money.
But the value of BIM extends well beyond the design and build stage to the entire lifecycle of assets – and this really is the whole point of it. The information contained in the model is available to the client to help them make the best decisions possible to maintain and operate assets during their life and at the decommissioning stage, which inevitably involves saving money. And although BIM is still in its infancy across industry, we are using it to help a range of clients realise the benefits of delivering asset planning, design, implementation and management across the entire lifecycle.
The eight2O alliance
Thames Water’s eight2O alliance has adopted BIM as part of their AMP6 commitment to effective management of whole lifecycle cost (TOTEX). BIM supports this in a number of ways, from creating and managing digital asset information to construction, commissioning and into asset management.
Turning that vision into reality has required significant changes to the way projects are delivered and the way digital information is created and managed. An incremental approach is maximising early benefits, and delivering ‘asset ready design’ that can be used throughout the asset lifecycle.
Thames Water Standards have been enhanced to align with the processes defined in UK Government BIM and Information Management guidance; a Common Data Environment has been configured; and new design and authoring tools adopted for the programme. A Thames asset tagging standard has been created to ensure digital information is produced in a consistent way, one which is complementary to Thames’s systems of record and asset management processes.
Project teams are choosing to design projects virtually and in 3D wherever possible. There is a focus on using standard designs and off-site manufacture to reduce time on site. Early engagement with the supply chain and operations is reducing costly change during construction. With these ‘foundations for success’ in place we will look to see how we can embrace new technology in the field to drive further efficiency and improve Thames Water’s asset data. This is particularly exciting in the water and wastewater infrastructure quadrants where new technology is being deployed to improve the quality of information captured during the work, reduce the length of disruption being experienced by customers and improving satisfaction scores, an important metric for OFWAT.
Aboard the BIM Bus
To aid greater collaboration among designers and stakeholders, eight2O is using a mobile design & solution studio, aka BIM Bus, which is fitted with multiple screens, seating areas and workstations.
The idea is to save time and money by using virtual-world design tools to resolve as many challenges as possible during the pre-construction phase. This supports the drive to use modular and standardised products and off-site construction wherever possible.
This latest approach to collaboration is driven by the need to achieve end user and customer satisfaction, protect the environment, and deliver a satisfactory financial outcome for the eight2O alliance partners.
Charing Cross geometry
High definition surveying (HDS) – aerial, mobile and static – is increasingly being used for many types of measured survey. This presents new opportunities for ‘accurate as built’ 3D models to be produced which can be used for digital 3D design, validation, virtual/augmented reality and ongoing maintenance. This delivers a quicker, more cost effective solution for the client, and in the case of Charing Cross, with no disruption to the operational working of the station.
Our geomatics team undertook high definition surveying and BIM modelling, which involved using static laser scanning to create a detailed and accurate ‘point cloud’ of the areas. Even in a live and busy station environment, HDS could survey the interior and external structural elements in less than a week.
Don Martindale, geomatics project manager, says: “Laser scanning helps minimise site time, reducing the health and safety risk. And the potential for re-visits is heavily reduced because once the initial data capture is complete, the survey is a desk-based exercise and any queries can be answered from the 3D laser point cloud.”
Dutch Roads and Waterways Agency
Further afield, we were at the forefront of efforts to persuade the Dutch Roads and Waterways Agency (Rijkswaterstaat Adviesdienst Geo-informatie en ICT) of the benefits of using digital aerial imagery to improve the reliability of mapped data.
Since 1994, we’ve been helping to maintain its mapping database, developing innovative software solutions to convert and supply of large volumes of data, and using photogrammetry techniques and aerial photography at a scale of 1:4000. Atkins has also processed the three-dimensional building models required for noise assessment activities, and consistently scored highly in the client’s supplier performance measurement.
Genoa bridge collapse: ‘That’s WHY the bridge gave out’ Engineer who built bridge explains
THE Genoa bridge collapse was caused by a major flaw in the supporting piles meaning the structure could not support the weight of heavy traffic, engineer Saverio Ferrari claimed.
Saverio Ferrari blamed the Genoa bridge collapse on the decision of the original building team not to build the supporting piles with anti-seismic materials.
Mr Ferrari, who worked as an engineer for the company that built the Morandi bridge, argued the flaw in the structure and the failure of authorities to redirect heavy traffic to alternative routes were the main reasons behind the deadly collapse.
Speaking to Corriere della Sera, the retired engineer said: “I worked with the Condotte company. Everything always collapsed when the failed company was involved.
“When the structure was put up, the supporting piles were not made to sustain earthquakes.”
A state funeral of 19 of the 43 victims was held on August 18 in Genoa at the presence of President Sergio Mattarella and members of the public.
Mr Ferrari claimed civil engineer Riccardo Morandi, who designed the bridge and whose name was given to the structure, had been aware of the decision and had complained to the building team.
He explained the trials to ensure the support capacity of the piles had been rushed and that the Morandi bridge already showcased major issues less than two years after its inauguration.
Mr Ferrari continued: “Mr Morandi got mad at the engineer in charge, he said ‘it needs to have a specific weight base to hold up.’ The piles were not anti-seismic.
“When the carrying capacity is not calculated you need to test the foundations. The test was done over five days. The chemical reaction of concrete cannot be completed within five days yet they kept on building.
Genoa Bridge collapese: Saverio Ferrari claimed the bridge was not made to sustain modern traffic
“In 1969 I stopped near the centre of the central span of the bridge and the oscillation of the structure from right to left was off by seven or eight centesimal.”
He added: “They did not learn how to redirect the heavier traffic from the 1980s onwards. That’s why the bridge gave out.”
Witnesses to the tragedy say the bridge collapsed during heavy rain “like flour” on to the railway lines and buildings below.
Rescue workers searching the rubble confirm 39 people have died and 15 are injured, numbers expected to rise.
A baby is reported to have died as well as two people who were in their homes after the enormous bridge collapsed.
Interior Minister Matteo Salvini, suggested EU budget constraints were the cause of the Genoa bridge collapse.
Speaking to reporters, Mr Salvini said: “If external constraints prevent us from spending to have safe roads and schools, then it really calls into question whether it makes sense to follow these rules.
“There can be no trade-off between fiscal rules and the safety of Italians.”
But while economic constraints are the main cause of the collapse, Mr Salvini’s allegations against the European Union seem to have little foundation.
Brussels has in place a £280.74billion (€315bn) programme designed to improve and renew infrastructure, and the EU issues annual recommendations to national governments about how they could best spend the money.
The advice for 2018 were released after the Italian election, which took place on March 4, and specifically called on the new government to “foster research, innovation, digital skills and infrastructure through better-targeted investment”.
You may not think about the bridges you cross on your way to work, but they’re far more than pretty structures that make your commute manageable. Bridges are crucial transportation links that carry road and rail traffic across rivers, gorges or other roads. When a bridge collapses or closes for repairs, it can cause massive traffic problems or strand people altogether, if they live on an island.
Some of the most massive and expensive engineering projects in history have involved building bridges. Although the general physics of bridge-building have been established for thousands of years, every bridge presents complicated factors that must be taken into consideration, such as the geology of the surrounding area, the amount of traffic, weatherand construction materials. Sometimes these factors are miscalculated, or something occurs that the bridge designers didn’t expect. The result can be tragic.
As we go through this list of 10 reasons why bridges collapse, keep in mind that most bridge collapses are the result of multiple factors. For example, a flood that damages bridge piers might not have caused a collapse — except for a design flaw and poor maintenance. Remove one of those factors and the bridge may have remained upright. On the other hand, sometimes a train smashes into a bridge and it just falls down. We’ll consider the possibilities, starting on the next page.
10. Earthquake
Earthquakes cause damage to all structures, including bridges. Major earthquakes can bring about the collapse of dozens of buildings, but collapsed bridges are often the most visible signs of the havoc an earthquake can wreak. Amidst the rubble and devastation, the sight of a damaged bridge from TV news helicopters stands out and becomes the iconic image of that particular disaster.
Such is the case with the Loma Prieta earthquake that struck the California coastal cities of Oakland and San Francisco in October 1989. The earthquake — named for a nearby mountain — caused 63 deaths, and the majority of them occurred in two bridge collapses: One person died as a section of the San Francisco-Oakland Bay Bridge gave way, and 42 others perished when a large portion of the Cypress Street Viaduct carrying Interstate 880 collapsed [source: USGS].
Fortunately, earthquake-triggered bridge collapses are relatively rare. In addition, builders can construct bridges in earthquake-prone areas to withstand tremors — or at least minimize the loss of life when one occurs.
9. Fire
Fire might be the rarest cause of bridge collapses, but fire has brought a few bridges down in the past. In fact, it used to happen much more often, when bridges were made out of wood. Train bridges were especially susceptible to fire, because the steel wheels of the train on the steel rails of the track frequently sent sparks shooting onto the bridge. If it was very dry or the wind fanned the sparks, the bridge could catch fire and burn completely down [source: Letchworth].
Bridge fires aren’t a thing of the distant past, however. Several modern bridges have also collapsed or been severely damaged due to fire. The cause is typically the crash of a tanker truck carrying a large amount of a highly flammable substance like gasoline. The crash triggers an explosion and a blaze so intense it melts the steel used to build the bridge. Eventually, the softened steel can no longer hold up the structure, and the bridge falls.
This is exactly what happened in 2009 when a tanker truck on I-75 near Detroit suddenly burst into flames directly under a bridge. The resulting inferno destroyed the bridge completely and forced the closing of I-75. Amazingly, no one was killed [source: Guthrie].
8.Train Crash
This type of bridge collapse is extraordinarily rare, but one of the worst rail disasters in history, the Eschede train disaster, was a bridge collapse caused by train impact. In 1998, a high-speed train traveling through Germany suffered a mechanical malfunction of one of the wheels. The broken wheel struck a switch and shifted it, throwing subsequent cars onto a different track. Moving at roughly 124 miles (200 kilometers) per hour, the cars derailed and slammed into the piers of a road bridge that passed over the railroad tracks at that point. The massive impact brought the bridge down directly onto the passenger cars of the train, crushing them. As a result, 101 people died in the accident [source: Oestern]. Eighty-three people lost their lives in a similar tragedy near Sydney, Australia in 1977 [source: ABC News].
A MOST UNUSUAL PLANE CRASH
Even rarer than trains crashing into bridges are airplane crashes that destroy bridges. The 1982 crash of Air Florida Flight 90 hit the 14th Street Bridge over Interstate 395 near Washington National Airport, killing several people in their cars. The bridge did not completely collapse, but did require extensive repairs [source: Wilber].
7. Boat Impact
Many bridges cross rivers and other bodies of water. Boats passing under a bridge are usually moving pretty slow (compared to trains), but boats have incredible mass. This means that even a barge, which typically creeps along at very slow speeds, can impart tremendous force if it collides with bridge pilings or piers. That force is sufficient to knock down the bridge in some cases.
An example of this type of incident is the collapse of the Judge William Seeber Bridge in New Orleans in 1993. The bridge carried road trafficover a canal, and a barge passing under the bridge struck a pier supporting the bridge and severed it. Nearly 150 feet (46 meters) of bridge collapsed as a result. One motorist driving on the bridge at the time died in the accident [source: NTSB]. More than a dozen major bridge collapses have been caused by boat collisions in the last 100 years [source: Wardhana].
6.Flood
Floods cause bridge collapses in a few different ways. Severe floods can cause rivers and creeks to overflow, picking up debris like trees, cars and parts of houses. When the river passes under a bridge, the high water level smashes the debris into the bridge. If the impact doesn’t destroy the bridge immediately, the weight of the piled up combined with the force of the flowing water pushing on it can bring the bridge down. This is what happened to the Conemaugh Viaduct in 1889, when the South Fork Dam in Pennsylvania collapsed, unleashing a massive torrent of water down the Little Conemaugh River [source: NPS].
Flooding can collapse bridges in a far more insidious way — by gradually wearing away the earth around and underneath the bridge piers. This process is known to bridge engineers as scour, and occurs whenever bridge foundations are placed underwater. The natural flow of the water can produce scour over many years, but bridges are built to withstand that type of erosion. Engineering techniques such as laying riprap, or layers of heavy rocks, can prevent scour. However, floods dramatically increase the force and volume of water affecting the bridge, and the damage to sediments can cause a bridge to collapse immediately or even days or months later. A study by the American Society of Civil Engineers determined that 53 percent of all bridge collapses are caused by flood and scour [source: Wardhana].
he Schoharie Creek Bridge is an example of a collapse caused by flood and scour. The bridge carried the New York State Thruway over the creek. In 1987, spring flooding caused high water levels. This washed sediment out from under one of the bridge piers, causing it to fall into a hole nearly 10 feet (3 meters) deep. Ten people died in the resulting bridge collapse [source: Storey & Delatte].
5. Construction Accidents
The Quebec Bridge collapsed twice during construction before finally being built.
A surprising number of bridges collapse as they’re being built. You might think these types of collapses aren’t as serious because no one was driving on the bridge at the time of the collapse. Unfortunately, some of the deadliest bridge collapses in history have occurred during the bridge’s construction. While a functional bridge may only have a few vehicles on it when it collapses, it takes hundreds of workers to build a bridge — all of whom may be in dangerous positions in case of collapse.
The 1907 collapse of the Quebec Bridge crossing the St. Lawrence River at Quebec City shows how engineering miscalculations can lead to disaster. The bridge was only partially constructed, but parts were already bending and breaking from the weight of the bridge itself. Engineers were concerned, but unable to take action swiftly enough. When it collapsed, 74 workers were killed [source: Structurae]. Amazingly, when the bridge was being rebuilt in 1916, it collapsed again, killing 13 more workers. It was finally completed in 1917 and remains in use today.
4. Manufacturing Defect
Some bridge collapses are mysteries when they first happen. It isn’t until a detailed investigation is completed that the true cause is revealed. Combing over the wreckage, engineers and accident investigators piece together the bridge’s history, looking at inspection reports and witness accounts of the collapse. At times, the simple failure of a small piece of the bridge caused the entire collapse. Sometimes low-grade or faulty materials were used, rendering the entire bridge too weak to withstand the rigors of time.
The 1967 collapse of the Silver Bridge over the Ohio River at Point Pleasant, W. Va. has become infamous for its connections to Mothman, a strange creature supposedly sighted near Point Pleasant in the months prior to the collapse (The 2002 Richard Gere film “The Mothman Prophecies,” chronicled the story). In truth, the collapse was due to a manufacturing defect in one of the steel eyebars that held the bridge up. Years of corrosion worsened the defect until it eventually failed, resulting in the deaths of 46 people [source: LeRose].
The 1994 collapse of the Seongsu Bridge in Korea was due to poor quality steel in some parts of the bridge and improper welding techniques in the bridge’s construction. 32 people were killed in the collapse [source: Korea National Emergency Management Agency]. The De la Concorde overpass in Laval, Quebec, Canada collapsed in 2006, killing five. The investigation revealed that some aspects of the bridge’s construction were done incorrectly and not according to the design, and that inferior quality concrete became too weak to support the structure.
3. Design Defect
Sometimes, bridges collapse due to design flaws
There are bridges whose collapse was inevitable before the bridge was ever built. The fault lies not with the construction of the bridge, but the design itself. The bridge is doomed to failure from the moment it was laid out on a blueprint.
One of the worst accidents in U.S. history is the collapse of the walkways in the Kansas City Hyatt Regency hotel. The walkways connected various parts of the second, third and fourth floors, overlooking the hotel lobby below — they were essentially pedestrian bridges inside the hotel. On July 17, 1981, the fourth-floor walkway collapsed, crashing onto the second-floor walkway which was directly below it. Both walkways then fell onto the lobby. Both the lobby and walkways were crowded with people watching or participating in an evening dance contest. The collapse killed 114 people [source: Associated Press].
Why did it happen? A redesign of the original plan caused the walkways to be constructed in such a way that structural elements ended up supporting the weight of both the second and fourth floor walkways simultaneously, doubling the load on them. Investigation revealed that even the original design was far too weak to support significant loads — and the redesign made the problem much worse [source: Martin]. It was nearly inevitable that they would collapse at the worst possible moment.
The 2007 collapse of the I-35 Bridge over the Mississippi River in Minneapolis, Minn. was also due to a design flaw. Steel gusset plates which bound key parts of the bridge structure together weren’t large enough. Additional weight placed on the bridge by concrete resurfacing and construction equipment caused the plates to buckle, and the entire bridge collapsed, killing 13 [source: NTSB].
2. Poor Maintenance
Poor maintenance is a difficult problem to diagnose in the wake of a bridge collapse. Many bridge collapses could have been prevented with more stringent inspection and maintenance routines, and lots of collapses that occur for other reasons are exacerbated by poor maintenance. When a bridge is designed, the engineers assume a certain level of maintenance that is necessary for the bridge to live out its intended lifespan. Rusted parts must be replaced, drainage areas cleared, new coats of paint applied and reinforcements added if traffic levels have increased.
A bridge carrying the Connecticut Turnpike over the Mianus River collapsed in the middle of the night in June 1983. The collapse was due to the failure of steel pins that had corroded. Investigators ruled that the bridge’s design and construction weren’t at fault — the collapse was blamed on deferred maintenance that would have spotted and replaced the rusted pins [source: NYCRoads].
1. Odd Occurrences
Some bridge collapses just can’t be explained at all.
We’ve discussed many causes of bridge collapse, but there are collapses that weren’t caused by any of the usual factors — rather, they were caused by events that can only be described as unusual.
In 1958, Cuba held the second Cuban Grand Prix. Legendary racer Juan Fangio was actually kidnapped by socialist revolutionaries before the race, but that wasn’t the worst thing about the event. The course was lined not with guard rails or safety fences, but with spectators standing right at the edge of the track. During the race, driver Armando Garcia Cifuentes lost control of his Ferrari and plowed into the crowd, destroying a temporary pedestrian bridge in the process. Seven people were killed [source: Edmondson].
The Lacey V. Murrow Memorial Bridge in Seattle crosses Lake Washington. It’s a floating bridge, suspended on pontoons. In 1990, a bizarre series of construction errors filled the pontoons with water used in resurfacing the bridge along with rain and lake water from a storm. Over the course of several hours, the bridge sank to the bottom of the lake.
The Winkley Bridge was a pedestrian suspension bridge in Arkansas. It was known for swaying significantly under load. In 1989, a group crossing the bridge started intentionally swinging it. They caused the bridge to sway so fiercely that the support structures failed and the bridge collapsed, killing five [source: Bridgehunter].
