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Road servicibility level

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Road servicibility level is considered as an Engineering standard used to evaluate road ability to service the traffic safely, comfortably and efficiently. The government will use the road serviceability level records and available data to determine the priorities in maintenance to reduce vehicles wear and prevent traffic jam.  The evaluation of a road will be based mainly on the physical condition of the road pavement and the flow of traffic: 1.Pavement Condition: The Present Serviceability Index (PSI)  The PSI isolate the physical condition of road pavement. This index was developed based on a wide and extensive transport road. It has a numerical scale to evaluate the pavement physical condition and it ranges from 0 to 5. 1-Excellent (5): Excellent pavement surface, smooth and free from defects. This level is ideal therotical because new road rarely get the score of 5 due to construction tolerances.  2-very good (4.0-4.9): New road or newly reinstated roads that provide...
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Traffic Signal Phasing: How Intersections Manage Vehicle and Pedestrian Movement

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 Traffic signal phasing is one of the most important concept in traffic Engineering. The traffic signal phasing concept define how the traffic signal divide the time among the different traffic movement at an intersection. On other word, it determines who moves, when moves and who will wait. Well deisgn signal phasing plan will enhace safety, reduce the delay and improve the traffic flow at an intersection. Furthermore,it will help in organizing the traffic movement at an intersection and prevent the conflict between vehicles, pedestrian and cyclist. -What Is a Traffic Signal Phase? Traffic signal phase is a specific part of the signal cycle which allows one movement or more to take place.  For example, in a four-leg intersection. The traffic could allow the traffic movement from north to south. While the traffic movement must be idle from the east to west. Then another phase would take place and allow the traffic movement from east to west, while traffic movement stopped from...
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Welding Techniques and Quality Inspection for Structural Steel Applications

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Types of Welding There are different types of welding used in steel structures, one of the most common being arc welding . In arc welding, the process uses a welding rod (electrode) to generate heat through an electric arc. The heat melts both the base metal and the tip of the electrode, allowing molten droplets of the electrode to deposit and fuse with the base metal. During this process, the weld area must be protected from atmospheric contamination. This protection is provided by inert gas or a vapor shield produced from the burning of the electrode coating. If this protective gas shield is not present, oxygen and nitrogen from the air may enter the molten weld metal, resulting in porosity , reduced toughness, and a brittle weld . Electrodes used in arc welding are classified into two types: Heavily-coated electrodes : Commonly used for structural welding, as they provide adequate shielding to protect the molten weld pool. Lightly-coated electrodes : Provide minimal shieldi...
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Pressure Reducing (or Pressure Breaking) Valves

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A pressure reducing valve (PRV) , also known as a pressure breaking valve , is used to reduce and regulate fluid pressure to a specific, safe value in order to protect downstream equipment and piping systems. These valves are commonly used in water supply and hydraulic systems , where the inlet pressure may be higher than the pressure rating of the downstream components. In such cases, the pressure reducing valve ensures that the downstream pressure remains within the allowable range of the equipment and pipes, preventing possible damage or system failure. The figure below shows the main components of a pressure reducing valve, which typically include a diaphragm , spring , inlet , and outlet . The valve is set to a preset pressure value . When the inlet pressure exceeds this preset limit, the diaphragm is pushed upward, compressing the spring and closing the valve partially to restrict flow — thereby reducing the downstream pressure. Conversely, when the inlet pressure drops bel...
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Flexible Pavement Layers and Their Components

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Flexible pavement is composed of several layers that work together to distribute traffic loads to the subgrade. These layers are generally divided into aggregate layers and asphaltic layers , each serving a specific function to ensure strength, stability, and durability of the pavement. Aggregate Layers The aggregate portion of the pavement usually consists of the subbase , roadbase , and sometimes a wet mix macadam (WMM) layer. These layers play a crucial role in supporting the asphaltic layers above and ensuring that loads are transferred smoothly to the subgrade without excessive settlement or deformation. 1-Subbase The subbase is a mixture of fine and coarse aggregates placed directly above the existing subgrade. Its main purpose is to improve the pavement’s overall bearing capacity, minimize settlement, and provide a uniform surface for the upper layers. Typically, the subbase should have a California Bearing Ratio (CBR) of not less than 30. The minimum thickness is usually abo...
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Binding wire for steel reinforcement

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  Binding wires are used to tie steel bars together. These wires are playing a significant role in maintaining the reinforcement stability and rigidity. Wires are used to tie the steel bars at intersections points. By tying the steel bars together, we ensure that the steel bars will not move from their locations during construction or during the time of concreting. In slabs, binding wires are used to tie longitudinal and transverse bars together. In columns, it is used to tie vertical bars with stirrups.   Figure 1 There are various types of binding wires such as  Black annealed baling wire, Stainless Steel Binding Wire, and PVC coated binding wires.  Black annealed baling wire used to tie black steel. The popular size for black wire ranges from 16 to 22 gauges. Stainless steel binding wires are used to bind stainless steel reinforcement. Stainless steel reinforcement is used in a harsh environment where the black steel gets rusted quickly. Therefore, stainless ...
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stress-strain diagram for aluminium alloy and rubber

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figure no:1 showing the stress-strain diagram for aluminum alloy. we can notice from the stress-stress diagram that aluminum has a considerable ductility. despite the absence of explicit yield point as in structural steel . the initial portion of the stress-strain curve is linear with a recognizable proportional limit. the proportional limit for aluminum alloy ranges from 70 to 410 Mpa (10 to 60 Ksi). aluminum alloy undergoes large strain before failure. ultimate stress ranges from 140 to 550 Mpa (20 to 80 Ksi). construction management: concrete construction bridge construction:How to become a bridge engineer Figure-1 Yield stress for aluminum alloy can be determined by drawing offset line parrel to the linear portion of the stress-strain curve. the straight line offset by a standard strain such as 0.002. the intersection point with the stress-strain curve is the point of yield stress. figure no:2 illustrates the concept of offset method. yield stress acquire...
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Rebar Splicing and Overlapping — ACI 318-19 Requirements Explained

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Reinforcement splicing or overlapping is a fundamental requirement in reinforced concrete structures. Because reinforcement bars (rebars) are manufactured in limited standard lengths—typically 12 m —it becomes necessary to splice or overlap them to achieve the required continuity in structural members. The main purpose of a splice is to ensure smooth stress transfer between adjacent bars through the surrounding concrete. The overlap length, commonly known as the splice length , must be long enough to safely transfer the tensile stresses from steel to concrete without causing bond failure. It is recommended to avoid splicing in high-stress zones such as areas of maximum moment, and to stagger the splices to prevent congestion and reduce stress concentration. The ACI 318-19 providing the following recommendatin and requirement for the lap splicing: 1. Splice Limitation by Bar Size Lap splicing is not permitted for reinforcement bars larger than 36 mm in diameter. 2. Non-Contact L...
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Pile cap

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Pile cap used to transfer the loads from superstructure to the piling. The pile cap is thick concrete mat rests on piles. It is part of the foundation and used to distribute the loads over the piles. Piles used when the soil bearing is not enough to carry loads of the structure. Figure 1  construction management: concrete construction bridge construction:How to become a bridge engineer Pile cap construction procedure Excavation around piles: After 7 days of the casting of the pile the concrete will gain approximately, 70% of it is compressive strength. The soil around piles will be removed to the required levels and dimension that allows construction of the pile cap. A step shall be made if the excavation is more than 1.5 m to prevent soil collapse. Figure 2 Pile head cutting: Concrete will be removed up to cut off level. If concrete under the cut off level is unsound. It shall be removed, and the pile will be repaired...
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Non-Working Pile Testing and Static Compression Load Test

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Purpose of Non-Working Piles Non-working piles are constructed at the beginning of the project to evaluate soil bearing capacity and determine the maximum settlement. These piles are loaded up to twice the working load. Based on the test results, the pile length may be adjusted. If the measured settlement exceeds the allowable limit, the pile length will be increased accordingly. construction management: concrete construction bridge construction:How to become a bridge engineer Static Compression Load Test The static compression load test provides insight into how the pile responds to loading. Settlement is measured at different load increments to determine the appropriate pile design length. The maximum applied load is typically twice the working load (2 × working load) or as specified by local standards. The following steps outline the testing procedure: A. Steel Cage Preparation The steel reinforcement cage is prepared in accordance with the approved shop drawings. ...
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Concrete repair-selecting the repair method

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Repairing concrete structure passes through various stages. Selecting the correct repair method will depend on completing the previous steps, such as determining the cause of concrete damage, evaluate the extent of the damage, and assess the need for repair. The completion of these steps will define the type of conditions the repair must resist, the available repair construction time period, and when repairs must be accomplished. The data collected from performing these steps will help in selecting which of the 15 standard methods is suitable and durable for repairing the damaged concrete structure. Figure 1 In general, the old concrete surface should be prepared before beginning with the repairing process. It is essential to remove all unsound concrete before applying the repairing. Improper preparing of damaged concrete structure will result in unsatisfactory repair with low durability. The first step in preparing the old concrete surface is the saw cutting of repairin...
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Prestressing stands debonding

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  Prestressing bridge concrete beams contributes to resisting the tensile stresses caused by the traffic loads and the beam's weight. Stressing concrete has various benefits, such as increasing concrete members' capacity, reducing the concrete member section, and increasing the span lengths for structures such as bridges and buildings. However,  The stressing of bridge beam ends can result in unwanted cracks. Therefore AASHTO calling for debonding a specific portion of strands at the beam end to minimize the stresses and reduce cracks. Figure 1 Debonding is achieved by wrapping the strands at the end of the beam with plastic. Wrapping the strand with plastic wrapping will prevent the strands from bonding with concrete, thus avoid transferring unwanted stress to the beam end. As a result, the unwanted cracks will be prevented by reducing the stress levels at the end of the beam.  
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Fiber Reinforced polymer for strengthening of reinforced concrete

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 Fiber-reinforced plastic (FRP) is a new technique to strengthen structures. Fiber-reinforced plastic has various types, such as a carbon-fiber-reinforced polymer (CFRP), glass fiber reinforced plastic (GFRP), and aramid fiber-reinforced polymer (AFRP).  The below table shows the mechanical properties of different fiber types.     Table 1 we can notice that carbon fiber reinforced polymer possesses better properties compared to other types. For example, the tensile strength of CFRP extra-high strength can reach 6200 MPA compared to a maximum tensile strength of 4135 MPA of other fiber types.   The FRP has various uses such as: Improved seismic performance of masonry walls Replacing missing steel reinforcement Increasing the strength and ductility of columns Increasing the loading capacity of structural elements Correcting structural design and/or construction defects Increasing resistance to seismic movement Improving service life and durability ...
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Repairing of concrete bulging

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Improper designing and installation of formwork for a concrete member can result in concrete Bulging. During the placing and compacting of concrete, forms may deflect largely in the weak areas. The deflection of forms will cause concrete to expand at this location, and this known as concrete Bulging. Concrete Bulging will spoil the appearance of a concrete member. Therefore we should always ensure that the forms are appropriately installed, and it is sufficiently supported to resist the concrete during placing and compacting. Bulging should be repaired in case we couldn't avoid it. The solution of concrete Bulging, offset, or surface irregularities are surface grinding. However, excessive surface grinding can weaken the concrete.  Figure 1 If the bulging or surface irregularities are small, grinding of concrete surface will be sufficient to remove surface irregularities. If the Bulging of concrete is significant, then the concrete should be chipped, and the surface...
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Bridge Diaphragm

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The main function of diaphragms is to provide a stiffening effect to deck slab in case bridge webs are not situated directly on top of bearings. Therefore, diaphragms may not be necessary in case bridge bearings are placed directly under the webs because loads in bridge decks can be directly transferred to the bearings.On the other hand, diaphragms also help to improve the load-sharing characteristics of bridges. Diaphragms also contribute to the provision of torsional restraint to the bridge deck. Diaphragm will be used also to resist stresses that occurs during the post-tensioning process. Post-tensioning hardware are casted inside the diaphragm. Figure 1 construction management: concrete construction bridge construction:How to become a bridge engineer Types of diaphragm: Diaphragm at the span end: this type of diaphragms will be located between two bridge spans or at the bridge abutments. Expansion joints will be used to connect bridge spans. This ...
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