1 English for Road and Bridge Engineering Unit 1: BRIDGE TYPES A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle Designs of bridges vary depending on the function of the bridge, the nature of the terrain where the bridge is constructed, the material used to make it and the funds available to build it There are six main types of bridges: beam bridges, truss bridges, arch bridges, cantilever bridges, suspension bridges and cable-stayed bridges Beam bridges Beam bridges are horizontal beams supported at each end by abutments, hence their structural name of simply supported When there is more than one span the intermediate supports are known as piers The earliest beam bridges were simple logs that sat across streams and similar simple structures In modern times, beam bridges are large box steel girder bridges Weight on top of the beam pushes straight down on the abutments at either end of the bridge They are made up mostly of wood or metal Beam bridges typically not exceed 76 m long The world's longest beam bridge is Lake Pontchartrain Causeway in southern Louisiana in the United States, at 38.35 km, with individual spans of 17 m Truss bridges A truss bridge is a bridge composed of connected elements (typically straight) which may be stressed from tension, compression, or sometimes both in response to dynamic loads Truss bridges are one of the oldest types of modern bridges The basic types of truss bridges shown in this article have simple designs which could be easily analyzed by nineteenth and early twentieth century engineers A truss bridge is economical to construct owing to its efficient use of materials Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Arch bridges Arch bridges have abutments at each end The earliest known arch bridges were built by the Greeks, and include the Arkadiko Bridge The weight of the bridge is thrust into the abutments at either side Dubai in the United Arab Emirates is currently building the Sheikh Rashid bin Saeed Crossing, which is scheduled for completion in 2012 When completed, it will be the largest arch bridge in the world Cantilever bridges Cantilever bridges are built using cantilevers— horizontal beams supported on only one end Most cantilever bridges use a pair of continuous spans that extend from opposite sides of the supporting piers to meet at the center of the obstacle the bridge crosses Cantilever bridges are constructed using much the same materials & techniques as beam bridges The difference comes in the action of the forces through the bridge The largest cantilever bridge is the 549 m Quebec Bridge in Quebec, Canada Suspension bridges Suspension bridges are suspended from cables The earliest suspension bridges were made of ropes or vines covered with pieces of bamboo In modern bridges, the cables hang from towers that are attached to caissons or cofferdams The caissons or cofferdams are implanted deep into the floor of a lake or river The longest suspension bridge in the world is the 3,909 m Akashi Kaikyo Bridge in Japan Cable-stayed bridges Cable-stayed bridges, like suspension bridges, are held up by cables However, in a cable-stayed bridge, less cable is required and the towers holding Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering the cables are proportionately shorter The first known cable-stayed bridge was designed in 1784 by C.T Loescher The longest cable-stayed bridge is the Sutong Bridge over the Yangtze River in China By use A bridge is designed for trains, pedestrian or road traffic, a pipeline or waterway for water transport or barge traffic An aqueduct is a bridge that carries water, resembling a viaduct, which is a bridge that connects points of equal height A roadrail bridge carries both road and rail traffic Bridges are subject to unplanned uses as well The areas underneath some bridges have become makeshift shelters and homes to homeless people, and the undersides of bridges all around the world are spots of prevalent graffiti Some bridges attract people attempting suicide, and become known as suicide bridges To create a beautiful image, some bridges are built much taller than necessary This type, often found in east-Asian style gardens, is called a Moon bridge, evoking a rising full moon Other garden bridges may cross only a dry bed of stream washed pebbles, intended only to convey an impression of a stream Often in palaces a bridge will be built over an artificial waterway as symbolic of a passage to an important place or state of mind A set of five bridges cross a sinuous waterway in an important courtyard of the Forbidden City in Beijing, the People's Republic of China The central bridge was reserved exclusively for the use of the Emperor, Empress, and their attendants (Source: Wikipedia) Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Match the words in column A with their meanings in column B A B a In theory, the individual parts of this structure only Beam bridge subject to tension and compression forces but not bending forces b The second oldest bridge type This structure doesn’t Truss bridge require piers in the center and uses a curved structure Arch bridge c The support is in the middle of a span, not the end Cantilever bridge d This structure is a continuous girder with one or more towers erected above piers in the middle of the span Suspension bridge e This structure often uses I-beams or box girders in their construction Cable-stayed bridge f This structure allows for the longest spans Word Pronounced beam biːm truss trʌs arch ɑːtʃ cantilever ˈkæntɪliːvə(r) suspension səˈspenʃn cable-stayed ˈkeɪbl-steɪ Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Vocabulary Word Pronounced Meaning span spæn the part of a bridge or an arch between one vertical support and another obstacle ˈɒbstəkl an object that is in your way and that makes it difficult for you to move forward terrain təˈreɪn used to refer to an area of land when you are mentioning its natural features material məˈtɪəriəl a substance that things can be made from fund fʌnd money that is available to be spent abutment əˈbʌtmənt stream striːm a masonry mass supporting and receiving the thrust of part of an arch or vault a continuous flow of liquid or gas box steel girder bɒks stiːl ˈɡɜːrdər element ˈelɪmənt a necessary or typical part of something tension ˈtenʃn the state of being stretched tight compression kəmˈpreʃn an increase in pressure of the charge in an engine or compressor obtained by reducing its volume dynamic load daɪˈnæmɪk ləʊd a force exerted by a moving body on a resisting member, usually in a relatively short time interval thrust θrʌst to push something/somebody suddenly or violently in a particular direction schedule ˈʃedjuːl a plan that lists all the work that you have to and when you must each thing continuous span kənˈtɪnjuəs spæn a span which is formed of a series of consecutive spans (over three or more supports) that are continuously or rigidly connected so that bending moment may be transmitted from one span to the adjacent ones pier pɪə(r) a large strong piece of wood, metal or stone that is used to support a roof, wall, bridge, etc Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering suspend səˈspend to hang something from something else cable ˈkeɪbl a set of wires, covered in plastic or rubber, that carries electricity, telephone signals, etc caisson kəˈsuːn a watertight chamber open at the bottom and containing air under pressure, used to carry out construction work under water cofferdam ˈkɒfəˌdæm a watertight structure, usually of sheet piling, that encloses an area under water, pumped dry to enable construction work to be carried out tower ˈtaʊə(r) a tall narrow building or part of a building, especially of a church or castle train treɪn a railway/railroad engine pulling a number of coaches/cars or trucks, taking people and goods from one place to another pedestrian pəˈdestriən a person walking in the street and not travelling in a vehicle road traffic rəʊd ˈtræfɪk a hard surface built for vehicles to travel on pipeline ˈpaɪplaɪn a series of pipes that are usually underground and are used for carrying oil, gas, etc over long distances waterway ˈwɔːtəweɪ a river, canal, etc along which boats can travel water transport ˈwɔːtə(r) ˈtrænspɔːt barge bɑːdʒ a large boat with a flat bottom, used for carrying goods and people on canals and rivers aqueduct ˈækwɪdʌkt a structure for carrying water, usually one built like a bridge across a valley or low ground road-rail bridge rəʊd-reɪl brɪdʒ makeshift shelter ˈmeɪkʃɪft ˈʃeltə(r) used temporarily for a particular purpose because the real thing is not available prevalent graffiti ˈprevələnt ɡrəˈfiːti Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering suicide ˈsuːɪsaɪd dry bed draɪ bed convey kənˈveɪ the act of killing yourself deliberately to make ideas, feelings, etc known to somebody pebble ˈpebl a smooth, round stone that is found in or near water artificial ˌɑːtɪˈfɪʃl made or produced to copy something natural; not real exclusively ɪkˈskluːsɪvli only given to one particular person or group attendant əˈtendənt a person whose job is to serve or help people in a public place Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Further reading Golden Gate Bridge The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the opening of the San Francisco Bay into the Pacific Ocean As part of both U.S Route 101 and California State Route 1, the structure links the city of San Francisco on the northern tip of the San Francisco Peninsula to Marin County The Golden Gate Bridge was the longest suspension bridge span in the world when it was completed in 1937, and has become one of the most internationally recognized symbols of San Francisco, California, and of the United States Despite its span length being surpassed by eight other bridges since its completion, it still has the second longest suspension bridge main span in the United States, after the VerrazanoNarrows Bridge in New York City It has been declared one of the modern Wonders of the World by the American Society of Civil Engineers The Frommers travel guide considers the Golden Gate Bridge "possibly the most beautiful, certainly the most photographed, bridge in the world" (Source: Wikipedia) Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Sutong Yangtze River Bridge The Sutong Yangtze River Bridge is a cable-stayed bridge that spans the Yangtze River in China between Nantong and Changshu, a satellite city of Suzhou, in Jiangsu province With a span of 1,088 metres (3,570 ft), it is the cable-stayed bridge with the longest main span in the world as of 2011 Its two side spans are 300 metres (980 ft) each, and there are also four small cable spans The bridge received the 2010 Outstanding Civil Engineering Achievement award (OCEA) from the American Society of Civil Engineers Two towers of the bridge are 306 metres (1,004 ft) high and thus the second tallest in the world The total bridge length is 8,206 metres (26,923 ft) Construction began in June 2003, and the bridge was linked up in June 2007 The bridge was opened to traffic on 25 May 2008 and was officially opened on 30 June 2008 Construction has been estimated to cost about US$1.7 billion The completion of the bridge makes the commute between Shanghai and Nantong, previously a four-hour ferry ride, shorten to about an hour It brings Nantong one step closer to becoming an important part of the Yangtze River Delta economic zone, and has further attracted foreign investors into the city The bridge is also pivotal in the development of poorer northern Jiangsu regions (Source: Wikipedia) Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Unit 2: BASIC BRIDGE TERMS An important first step in understanding the principles and processes of bridge construction is learning basic bridge terminology Although bridges vary widely in material and design, there are many components that are common to all bridges In general, these components may be classified either as parts of a bridge superstructure or as parts of a bridge substructure SUPERSTRUCTURE The superstructure consists of the components that actually span the obstacle the bridge is intended to cross and includes the following: Bridge deck Structural members Parapets (bridge railings), handrails, sidewalk, lighting and some drainage features The deck is the roadway portion of a bridge, including shoulders Most bridge decks are constructed as reinforced concrete slabs, but timber decks are occasionally used in rural areas and open-grid steel decks are used in some movable bridge designs (bascule bridge) As polymers and fiber technologies improve, Fiber Reinforced Polymer (FRP) decks may be used Bridge decks are required to conform to the grade of the approach roadway so that there is no bump or dip as a vehicle crosses onto or off of the bridge The most common causes of premature deck failure are: Insufficient concrete strength from an improper mix design, too much water, improper amounts of air entraining admixtures, segregation, or improper curing Improper concrete placement, such as failure to consolidate the mix as the concrete is placed, pouring the concrete so slowly that the concrete begins the initial set, or not maintaining a placement rate Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Further reading INTERSECTION TYPES Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering INTERSECTION CONFIGURATIONS Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Unit 7: PUBLIC TRANSPORT INTRODUCTION Public transport (also public transportation or public transit) is a shared passenger transportation service which is available for use by the general public, as distinct from modes such as taxicab, car pooling or hired buses which are not shared by strangers without private arrangement Public transport modes include buses, trolleybuses, trams and trains, rapid transit (metro/subways/undergrounds etc) and ferries Public transport between cities is dominated by airlines, coaches, and intercity rail High-speed rail networks are being developed in many parts of the world Most public transport runs to a scheduled timetable with the most frequent services running to a headway Share taxi offers on-demand services in many parts of the world and some services will wait until the vehicle is full before it starts Paratransit is sometimes used in areas of low-demand and for people who need a door-to-door service Urban public transport may be provided by one or more private transport operators or by a transit authority Public transport services are usually funded by government subsidies and fares charged to each passenger Services are normally regulated and possibly subsidized from local or national tax revenue Fully subsidized, zero-fare (free) services operate in some towns and cities For historical and economic reasons, there are differences internationally regarding use and extent of public transport While countries in Old World tend to have extensive and frequent systems serving their old and dense cities, many cities of the New World have more sprawl and much less comprehensive public transport Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering THE ADVANTAGES OF USING PUBLIC TRANSPORT SYSTEMS A public transport system is a shared public mass transportation form that is provided for use to the general public These systems are organized and efficient, and come in many forms, from the Subway or bus to a taxi to trams, coaches, airplanes, and high speed railways Many of us are so reliant upon our own personal vehicles that we rarely give any thought to the benefits of using these public modes of transportation However, if you live in a city or other area where you could easily utilize these daily, you should know that it can actually make your life easier There are many reasons why public transport is a great idea It can save you a lot of money Everyone knows how expensive it is to fill your car up with gas Not to mention the cost of the car itself and insurance protection that you need to cover it Owning your own vehicle is a pretty major expense And while you have to pay to ride public transportation systems, it will likely end up being a whole lot cheaper, especially if you it often It can also offer great convenience Tired of fighting traffic day after day to get to your job? Consider that the subway or tram may just miss all this traffic Not to mention the fact that it allows you more time to be focused on other things Rather than driving, you can be making business calls, planning your day, or jotting down notes All you have to is show up and get on board and you will be escorted to your destination The service could not be better There are some who like to be in control, and feel that they can be more so when they drive their own vehicle However, if you call forking out a lot of money each month and waiting in hour long traffic being in control, then consider the alternative: peacefully relaxing in the back of a cab or flying through the air on a plane, blissfully unaware of traffic accidents below that will have traffic backed up for hours Public transports can also be quite helpful when you are traveling to other countries It is obviously not realistic to consider taking your car overseas, so your only alternatives are to rent a vehicle when you get there or ride the public system When you realize that roadways and signs in other countries are often a little confusing, you may opt for allowing yourself to be escorted from place to place It will make your day more relaxing, too Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering PUBLIC TRANSPORT VERSUS OWNING A CAR Public transport services are offered in most major cities all around the world It offers a cheap alternative to the cost of owning a vehicle or paying for a taxi when you visit outside of your home town Even if you have the money to purchase a car to begin with, you have a number of other expenses to deal with The cost of gas and maintenance fees such as oil changes and new tires can add up to be more than the fees for a monthly pass While it depends on the time of day you are travelling, it can even be a faster way to get into town Otherwise, it's up to you determine if you can have the extra time to spend on travel Parking fees should be considered as well If you aren't paying for hourly parking, you will be looking at high fees for day passes or monthly parking Without your own regular space, you need to spend time and energy finding a place to put your car and hope that you're within a reasonable walking distance to your work or target location You also not have to worry about the extra money needed to repair a car when it breaks down Whether money is tight or not, it is never fun to have to worry about getting your car to a shop and handing over hard earned cash that you would otherwise not have to spend Getting to know public transportation in any city, whether it's in your home town or not, is not always easy Unfortunately, it is not going to be the same everywhere you go However, once you figure out how to use the public transport where you are it can be well worth the effort you put in Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Vocabulary Word Pronounced Meaning public transport public transportation public transit passenger taxicab car pooling hired bus trolleybus tram train metro subway underground ferry scheduled timetable coach intercity rail paratransit transit authority personal vehicle benefit insurance protection peacefully blissfully public transport service maintenance fee parking fee extra money energy Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Further reading HANOI METRO Hanoi Urban Metro (Hanoi Metro) is a metro rail system that will be developed in Hanoi, Vietnam, by 2020 The project is part of an integrated development programme for urban transport in Hanoi and will provide a safe, efficient and clean urban transportation system It is the fourth-biggest project in Vietnam to utilise the Japanese Government’s official development assistance capital Hanoi is the capital of Vietnam and the country's second-largest city, with a population of about six million Many trains, including services to Hai Phong and Ho Chi Minh City, depart from Hanoi station The Union Express travels from Hanoi to Ho Chi Minh City, stopping at cities and towns along the route Commuters in Hanoi use motorbikes, buses, taxis and bicycles The metro project is part of the Vietnam Ministry of Transport's master plan, which aims to reduce the use of private transport and enhance the urban environment The metro system will have five routes The main route - line - will be the first metro line in Hanoi On completion, the route will provide transport to 200,000 passengers a day It broke ground in September 2010 and is expected to become operational by the end of 2015 The entire project is being carried out by Hanoi Metropolitan Rail Transport Project Board (HRB), formerly known as the Hanoi Authority for Tram and Public Transport Development Management (HATD) Technical studies of the system were completed in 2009 Project The feasibility study for a Hanoi metro pilot route / line was completed in October 2005 and design of the pilot line started in 2007 The pilot route will be an eastwestbound line and will connect 12 stations in the city bewteen Hanoi station and Nhon depot The 12.5km pilot line will incorporate a 5.5km single track U-viaduct and a 4km twin tunnel structure The system will include 9.6km of elevated and 2.9km of Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering underground sections, and will use 20m metro trains top transport 900 passengers in a single trip The trains will run at 80km/h, covering the entire route in 20 minutes International consulting engineers HRB and SYSTRA signed two contracts to construct the pilot line Each contract is worth €36m and the total cost of the pilot line is about €500m SYSTRA will assist with the commissioning, launch and operation of the service and will supervise the construction and manufacture of rolling stock It also provided design studies and assessed bids The metro's infrastructure will include a viaduct, an underground section, stations, a depot and rolling stock maintenance centre and power supply stations The construction of line two will begin in 2011 and is expected to be operational in January 2016 Line routes Hanoi Metro's routes will include Nam Thang Long to Tran Hung Dao, Nhon to Hanoi station, Cat Linh to Ha Dong and Yen Vien to Ngoc Hoi The route connecting Nam Thang Long and Tran Hung Dao will be 11.54km long and serve ten stations The line will include an 8.55km underground section The pilot line (line 3) between Nhon depot and Hanoi station will start at Nhon and travel to Cau Giay via National Highway 32, Ho Tung Mau and Xuan Thuy It will also pass through Kim Ma, Nui Truc and Quoc Tu Giam The 13km-route connecting Cat Linh and Ha Dong will travel from Cat Linh to Thai Thinh via Hao Nam and Hoang Cau From Thai Thinh the line will move towards National Highway 6, connecting Nga Tu So, Nguyen Trai, Tran Phu and Quang Trung Financing The project is being coordinated and financed by several organisations including the World Bank, the Asian Development Bank and the European Investment Bank The latter has granted a €173m loan to help fund the construction of line Part of the project is being financed by Agence Française de Développement (AFD) The money provided by AFD is being used to construct the pilot line's infrastructure The project is being co-financed by bilateral overseas development assistance loans They amount to €280m, of which €200m is tied and €80m is untied Source: railway-technology.com Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Unit 8: ROAD CONSTRUCTION Road construction requires the creation of a continuous right-of-way, overcoming geographic obstacles and having grades low enough to permit vehicle or foot travel and may be required to meet standards set by law or official guidelines The process is often begun with the removal of earth and rock by digging or blasting, construction of embankments, bridges and tunnels, and removal of vegetation (this may involve deforestation) and followed by the laying of pavement material A variety of road building equipment is employed in road building After design, approval, planning, legal and environmental considerations have been addressed alignment of the road is set out by a surveyor The Radii and gradient are designed and staked out to best suit the natural ground levels and minimize the amount of cut and fill Surveyor at work with a leveling Asphalt layer and roller instrument Roads are designed and built for primary use by vehicular and pedestrian traffic Storm drainage and environmental considerations are a major concern Erosion and sediment controls are constructed to prevent detrimental effects Drainage lines are laid with sealed joints in the road easement with runoff coefficients and characteristics adequate for the land zoning and storm water system Drainage systems must be capable of carrying the ultimate design flow from the upstream catchment with approval for the outfall from the appropriate authority to a watercourse, creek, river or the sea for drainage discharge A borrow pit (source for obtaining fill, gravel, and rock) and a water source should be located near or in reasonable distance to the road construction site Approval from local authorities may be required to draw water or for working (crushing and Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering screening) of materials for construction needs The top soil and vegetation is removed from the borrow pit and stockpiled for subsequent rehabilitation of the extraction area Side slopes in the excavation area not steeper than one vertical to two horizontal for safety reasons Old road surfaces, fences, and buildings may need to be removed before construction can begin Trees in the road construction area may be marked for retention These protected trees should not have the topsoil within the area of the tree's drip line removed and the area should be kept clear of construction material and equipment Compensation or replacement may be required if a protected tree is damaged Much of the vegetation may be mulched and put aside for use during reinstatement The topsoil is usually stripped and stockpiled nearby for rehabilitation of newly constructed embankments along the road Stumps and roots are removed and holes filled as required before the earthwork begins Final rehabilitation after road construction is completed will include seeding, planting, watering and other activities to reinstate the area to be consistent with the untouched surrounding areas Processes during earthwork include excavation, removal of material to spoil, filling, compacting, construction and trimming If rock or other unsuitable material is discovered it is removed, moisture content is managed and replaced with standard fill compacted to 90% relative compaction Generally blasting of rock is discouraged in the road bed When a depression must be filled to come up to the road grade the native bed is compacted after the topsoil has been removed The fill is made by the "compacted layer method" where a layer of fill is spread then compacted to specifications, the process is repeated until the desired grade is reached Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Typical pavement strata for a heavily traveled road General fill material should be free of organics, meet minimum California bearing ratio (CBR) results and have a low plasticity index The lower fill generally comprises sand or a sand-rich mixture with fine gravel, which acts as an inhibitor to the growth of plants or other vegetable matter The compacted fill also serves as lower-stratum drainage Select second fill (sieved) should be composed of gravel, decomposed rock or broken rock below a specified Particle size and be free of large lumps of clay Sand clay fill may also be used The road bed must be "proof rolled" after each layer of fill is compacted If a roller passes over an area without creating visible deformation or spring the section is deemed to comply The completed road way is finished by paving or left with a gravel or other natural surface The type of road surface is dependent on economic factors and expected usage Safety improvements like Traffic signs, Crash barriers, Raised pavement markers, and other forms of Road surface marking are installed According to a May 2009 report by the American Association of State Highway and Transportation Officials (AASHTO) and TRIP—a national transportation research organization—driving on rough roads costs the average American motorist approximately $400 a year in extra vehicle operating costs Drivers living in urban areas with populations more than 250,000 are paying upwards of $750 more annually because of accelerated vehicle deterioration, increased maintenance, additional fuel consumption, and tire wear caused by poor road conditions Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering When a single carriageway road is converted into dual carriageway by building a second separate carriageway alongside the first, it is usually referred to as duplication, twinning or doubling The original carriageway is changed from twoway to become one-way, while the new carriageway is one-way in the opposite direction In the same way as converting railway lines from single track to double track, the new carriageway is not always constructed directly alongside the existing carriageway Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Vocabulary Word Pronounced Meaning Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Further reading ROAD MAINTENANCE Like all structures, roads deteriorate over time Deterioration is primarily due to accumulated damage from vehicles, however environmental effects such as frost heaves, thermal cracking and oxidation often contribute According to a series of experiments carried out in the late 1950s, called the AASHO Road Test, it was empirically determined that the effective damage done to the road is roughly proportional to the Fourth power of axle weight A typical tractor-trailer weighing 80,000 pounds (36.287 t) with 8,000 pounds (3.629 t) on the steer axle and 36,000 pounds (16.329 t) on both of the tandem axle groups is expected to 7,800 times more damage than a passenger vehicle with 2,000 pounds (0.907 t) on each axle Potholes on roads are caused by rain damage and vehicle braking or related construction works Pavements are designed for an expected service life or design life In some UK countries the standard design life is 40 years for new bitumen and concrete pavement Maintenance is considered in the whole life cost of the road with service at 10, 20 and 30 year milestones Roads can be and are designed for a variety of lives (8-, 15-, 30-, and 60-year designs) When pavement lasts longer than its intended life, it may have been overbuilt, and the original costs may have been too high When a pavement fails before its intended design life, the owner may have excessive repair and rehabilitation costs Many concrete pavements built since the 1950s have significantly outlived their intended design lives Some roads like Chicago, Illinois's "Wacker Drive", a major two-level viaduct in downtown area are being rebuilt with a designed service life of 100 years Virtually all roads require some form of maintenance before they come to the end of their service life Pro-active agencies use pavement management techniques to continually monitor road conditions and schedule preventive maintenance treatments as needed to prolong the lifespan of their roads Technically advanced agencies monitor the road network surface condition with sophisticated equipment such as laser/inertial Profilometers These measurements include road curvature, Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering cross slope, asperity, roughness, rutting and texture (roads) This data is fed into a pavement management system, which recommends the best maintenance or construction treatment to correct the damage that has occurred Maintenance treatments for asphalt concrete generally include crack sealing, surface rejuvenating, fog sealing, micro-milling and surface treatments Thin surfacing preserves, protects and improves the functional condition of the road while reducing the need for routing maintenance, leading to extended service life without increasing structural capacity Failure to maintain roads properly can create significant costs to society, in a 2009 report released by the American Association of State Highway and Transportation Officials (USA) about 50% of the roads in the USA are in bad condition with urban areas worse The report estimates that urban drivers pay an average of $746/year on vehicle repairs while the average US motorist pays about $335/year In contrast, the average motorist pays about $171/year in road maintenance taxes (based on 600 gallons/year and $0.285/gallon tax) Authors: Do Viet Hai – Phan Hoang Nam [...]... are typically anchored to the substructure by a number of expansion bearings and a single fixed bearing Many bridges have both simple and continuous spans Authors: Do Viet Hai – Phan Hoang Nam 1 English for Road and Bridge Engineering Unit 3: BRIDGE CONSTRUCTION Because each bridge is uniquely designed for a specific site and function, the construction process also varies from one bridge to another... Hai – Phan Hoang Nam 5 English for Road and Bridge Engineering moisture barrier ˈmɔɪstʃə ˈbærɪə rebar ˈriːbɑː skid-resistant skɪd rɪˈzɪstənt rough rʌf burlap ˈbɜːlæp discourage dɪˈsˈkʌrɪdʒ sealant ˈsiːlənt seal siːl Authors: Do Viet Hai – Phan Hoang Nam 6 English for Road and Bridge Engineering Further reading Quality Control The design and construction of a bridge must meet standards developed by several... can either be formed and cast in place, or be precast and lifted into place and attached to the foundation Bridge abutments are prepared on the riverbank where the bridge end will rest A concrete backwall is formed and poured between the top of the bank and the riverbed; this is a retaining wall for the soil beyond the end of the bridge A ledge (seat) for the bridge end to rest on is formed in the... ˈsteɪbɪˌlaɪz Authors: Do Viet Hai – Phan Hoang Nam 9 English for Road and Bridge Engineering Further reading Spans and Span Length The terms bridge and span are used interchangeable; however, to avoid confusion and misunderstanding, Technicians and construction personnel draw a distinction between the two A bridge is made up one or more spans A span is a segment of a bridge that crosses from one substructure... across the girders to form a solid platform, completing the bridge superstructure One manufacturer offers a 4.5 in (11.43 cm) deep corrugated panel of heavy (7-or 9-gauge) steel, for example Authors: Do Viet Hai – Phan Hoang Nam 3 English for Road and Bridge Engineering Another alternative is a stay-in-place steel form for the concrete deck that will be poured later Figure 2 Steel girder bridge construction...2 English for Road and Bridge Engineering 3 Insufficient concrete cover due to improper screed settings or incorrect installation of the deck forms and/ or reinforcement A bridge deck is usually supported by structural members The most common types are: 1 Steel I-beams and girders 2 Precast, prestressed, reinforced concrete bulb T beams 3 Precast, prestressed, reinforced concrete I beams... Cables and Arches, Frames, and Surface Structures Authors: Do Viet Hai – Phan Hoang Nam 2 English for Road and Bridge Engineering Loads Once the dimensional requirement for a structure have been defined, it becomes necessary to determine the loads the structure must support In order to design a structure, it is therefore necessary to first specify the loads that act on it The design loading for a structure... method of sections and method of joints for truss analysis, moment distribution method for small rigid frames, and portal frame and cantilever method for large rigid frames Except for moment distribution, which came into use in the 1930s, these methods were developed in their current forms in the second half of the nineteenth century They are still used for small structures and for preliminary design... Viet Hai – Phan Hoang Nam 8 English for Road and Bridge Engineering Further reading Loads on Architectural and Civil Engineering Structures Building codes require that structures be designed and built to safely resist all actions that they are likely to face during their service life, while remaining fit for use Minimum loads or actions are specified in these building codes for types of structures, geographic... Bridge Engineering Unit 5: ROAD DESIGN Road selection and design depend on the nature of the subgrade; the traffic and drainage conditions; the construction time available; the supply of local and imported materials; and the engineer equipment, personnel, and expertise available The completed design must then meet the requirements for the given load class and allow safe and efficient traffic movement ... island divisional island Authors: Do Viet Hai – Phan Hoang Nam English for Road and Bridge Engineering Further reading INTERSECTION TYPES Authors: Do Viet Hai – Phan Hoang Nam English for Road and. .. Hoang Nam English for Road and Bridge Engineering Unit 2: BASIC BRIDGE TERMS An important first step in understanding the principles and processes of bridge construction is learning basic bridge. .. Hoang Nam English for Road and Bridge Engineering Further reading Spans and Span Length The terms bridge and span are used interchangeable; however, to avoid confusion and misunderstanding, Technicians