Module 2: Highway Alignment, Surveys & Road Types in the Philippines PDF

NCE_3101 | Highway and Railroad Engineering o Economical - alignment should be MODULE 2 economical during construction,...

NCE_3101 | Highway and Railroad Engineering o Economical - alignment should be MODULE 2 economical during construction, operation, and maintenance. HIGHWAY ALIGNMENT, SURVEYS AND o Short - distance between the initial DIFFERENT TYPES OF ROADS IN THE and final point need to be short so PHILIPPINES AND ABROAD as to reduce the construction cost. o Easy – construction materials if - Roads in the Philippines are categorized present at the place of according to their purposes and construction makes the connectivity. construction easier. Similarly, it - It is essential to comprehend these should be easy during the divisions because every kind of road has a operation of vehicles with easy distinct function in the transportation gradients and curves. system, there are many varieties. o Comfort - alignment should be - Every kind of road is essential for fixed such that it provides comfort promoting social development, economic to the drivers and the passengers. expansion, and regional connectivity. DIFFERENT ROAD CLASSIFICATIONS IN THE HIGHWAY ALIGNMENT PHILIPPINES - Location of the highway's center line on National Primary Roads the earth. Both vertical and horizontal - National primary roads directly link major alignment are components of highway cities with population of atleast 100,000 alignment. people. - Highway alignment projections in two - Functions: planes are referred to as horizontal o Connects major cities and urban alignment and vertical alignment, centers. respectively, when they are in the o Facilitates long-distance travel. horizontal or vertical directions. o Support national economic - Selection of alignment must minimize development. overall costs during construction, National Secondary Roads operation, and maintenance. - National secondary road connect cities to - Requirements of Highway Alignment: national primary roads, major ports, o Safe - alignment need to be safe airport and tour service center. during construction, operation and - Functions: maintenance especially at slopes, o Supports intercity and embankments and cutting. interregional connectivity Reviewer | SYR NCE_3101 | Highway and Railroad Engineering o Enhance access to national o Enhances urban mobility and infrastructure. accessibility. o Facilitates movements of goods Barangay Roads and people across the region. - Barangay roads refer to the local roads National Tertiary Roads within barangays, providing essential - Encompass local roads under the connectivity within communities. Department of Public Works and - Functions: Highways. (DPWH) o Connects barangays to municipal - Functions: and city centers. o Provides access to rural o Supports local transportation communities and villages needs. o Supports local transportation o Facilitates access to community needs. services. o Enhance connectivity within Expressways provinces. - Expressways are high-speed highways Provincial Roads within limited access, featuring - Provincial roads connects cities and interchanges and tolls for passage. municipalities through rural areas without - Functions: crossing national roads. o Facilitates rapid long-distance - Functions: travel. o Links cities and municipalities o Enhances traffic flow and safety. within provinces. o Supports economic development o Supports agricultural activities and along corridors. rural development. Bypasses o Enhances accessibilities to remote - Bypasses are roads or highway designed areas. to divert traffic away from built-up areas, Municipal and City Roads reducing congestion and improving road - Are connector of provincial and national safety. roads, facilitating local mobility and - Functions: access to services by enhancing access to o Allows through traffic to bypass services by enhancing accessibilities to urban centers. major municipal and inter-barangay o Reduces congestion and travel travel. time for long-distance commuters. - Functions: o Enhances safety by seperating o Provides intra-city transportation. local and through traffic. o Connects residential, commercial and government areas. DIFFERENT ROAD CLASSIFICATIONS ABROAD Reviewer | SYR NCE_3101 | Highway and Railroad Engineering Interstate Highway - Traffic Surveys - are essential for - One of the main roads that are part of a US understanding traffic patterns, managing system of large roads that go across congestion, and improving road safety. states to connect many cities - Road Safety Surveys - are vital for - Functions: identifying hazards, understanding o Fastes road to use in Abroad to accident patterns, and improving road cross different cities. safety. These surveys help in formulating State Highway strategies to reduce accidents and - They are roads that connect the capital enhance the overall safety of the road city of a state with its district network. headquarters, major towns and other - Road Network Surveys - are crucial for highways. assessing and managing the road - Functions: infrastructure. They provide valuable o Basic road to access to one insights into the structure, connectivity, property to another. and functionality of the road network. Country Road - Economic and Social Impact Survey - - Country road is a usually unpaved rural assess the broader effects of road road off the main highway. infrastructure on communities and - Functions: economies. These surveys are crucial for o Offers better transportation understanding how road projects facilities. influence local development, property Local Road values, social interactions, and overall - Local road which has been dedicated to quality of life. the public people to use in traveling. - Infrastructure Quality Survey - focus on - Functions: evaluating the condition and performance o Provides a high level of safety and of infrastructure assets, including roads, access to neighborhoods services bridges, tunnels and etc. These surveys and facilities. are essential for ensuring that infrastructure meets safety standards, SURVEYS OF DIFFERENT TYPES OF ROADS IN performs effectively, and requires THE PHILIPPINES appropriate maintenance or upgrades. - Road Condition Survey – are critical for maintaining and improving the quality of SURVEY OF DIFFERENT TYPES OF ROADS IN road infrastructure. In the Philippines, ABROAD these surveys help in identifying road - Interstate Highway Survey - examines issues and planning necessary the condition and functionality of interventions. highways connecting different states. This Reviewer | SYR NCE_3101 | Highway and Railroad Engineering helps identify areas needing improvement events, ensuring safety and reducing and ensures the roads remain safe and damage during tremors. effective for travelers. - Structural Health Monitoring - involves - Pedestrian and Cyclist Flow Survey - regularly inspecting and assessing the tracks the movement and volume of condition of bridges, tunnels, and other pedestrians and cyclists in specific areas. infrastructure to detect any signs of This information helps in designing better damage or deterioration. This helps infrastructure and safety measures for ensure safety and prolong the lifespan of nonmotorized road users. these critical structures. - Road User Survey - collect data on how drivers, passengers,and other road users interact with the road system. This helps planners and engineers understand traffic patterns and identify areas needing improvement. - Ice and Snow Traction Survey - evaluate how well different road surfaces and vehicles perform in icy and snowy conditions. This information helps in designing better winter road maintenance strategies and improving safety for drivers. - Winter Road Maintennce Effectiveness Survey – assess how well various treatments and techniques, like salt spreading and snow plowing, keep roads safe during winter. They help transportation agencies fine-tune their methods for clearing ice and snow, ensuring roads remain navigable and reducing accidents. - Seismic Impact Survey - evaluate how earthquakes and ground vibrations affect roadways and bridges. They help engineers design and reinforce infrastructure to withstand seismic Reviewer | SYR NCE_3101 | Highway and Railroad Engineering - Components: MODULE 3 o Radius – Directly influences the sharpness of the curve; a smaller HORIZONTAL AND VERTICAL ALIGNMENTS IN radius means a sharper curve. HIGHWAY AND RAILWAY DESIGN AND IT’S o Superelevation – Banking if the GEOMETRIC DESIGN road surface to counteract the lateral acceleration forces HORIZONTAL ALIGNMENT experienced by vehicles. - Is a cruicial aspect of road and railway o Sight Distance – Distance a driver design and focuses on the layout of the can see ahead along the curve, path in the horizontal plane. which is critical for safety. - It determines how a route curves and - Curved Design Considerations: follows the terrain, ensuring safety, o Minimum Radius – Determined by comfort, and efficiency in transportation. the design speed and the maximum allowable Design Speed superelevation. - Is the maximum safe speed that can be o Transition Curves – Used to maintained over a specified section of a gradually change the alignment roadway under ideal conditions. from straight to curved, improving - It determines the geometric features of a driver comfort and safety. roadway, including the radius of o Safety – Proper design ensures horizontal curves, super elevation, and vehicles can navigate the curve sight distance. safely at the design speed without - Factors influencing design speed: skidding or rolling over. o Terrain (flat, rolling, or mountainous) VERTICAL ALIGNMENT o Roadway function (urban, rural, - Generally defined as the presence of arterial, collector, local roads) heights and depths in vertical axis with o Anticipated traffic volume and respect to horizontal axis of alignment. type These heights and depths in roads may be - The design speed should match or exceed in the form of gradients (straight lines in a the speed that drivers are expected to vertical plane) or vertical curves. travel under free-flowing traffic - The design vertical alignment involves conditions, ensuring safety and efficiency. selection of suitable grades for the tangent sections and the design of the Horizontal Curve vertical curves. - Is a curved section of a road that changes the alignment or direction of the roadway. Reviewer | SYR NCE_3101 | Highway and Railroad Engineering - Topography of the area which the road - Minimum gradient is used at locations traverses has a significant impact on the where surface drainage is important. design of the vertical alignment. - Camber will take care of the lateral drainage, but the longitudinal drainage GRADIENT along the side drains require some slope - A road gradient is a longitudinal slope for smooth flow of water. Therefore provided to the formation level of a road minimum gradient is provided for drainage along its alignment. purposes and it depends on the rain fall, - “Gradient of Road is defined as the rate of type of soil and other site conditions. rising or falls along the length of the road with respect to the horizontal alignment”. GRADE COMPENSATION - When a horizontal circular curve lies in Ruling Gradient vertical curve, there will be an increased - Ruling gradient or design gradient is the resistance offered bu the circular curve in maximum gradient with which the the form of a curve resistance in addition designer attempts to design the vertical to the component of gravity. profile of the grade, speed, pulling power - IRC (Indian Roads Congress) of the vehicle and the presence of the specifications for grade compensations horizontal curve. are as follow: o For grades flatter than 4%, grade Limiting Gradient compensation is not required due - This gradient is provided as shorter to negligible loss of tractive force. stretches in highways. Whenever ruling o Grade compensation is (30 + R)/R gradient costs high for the hilly terrains o Maximum value of gradient then limiting gradient is provided which compensation = 75/R will reduce the cost. ▪ R = radius of horizontal - This gradient is adopted frequently in curve in meters. terrains with limited stretches. VERTICAL CURVES Exceptional Gradient - Generally two types of vertical curves are - Exceptional gradients are very steeper there to adopt for the vertical alignment. gradients given at unavoidable situations. - They should be limited for short stretches Summit Curve not exceeding about 100 m at a stretch. - Also knows as the crest curve - Are convex upward and concave Minimum Gradient downward. Reviewer | SYR NCE_3101 | Highway and Railroad Engineering - There are four different cases involved in adoption of summit curve as follows. - Deviation Angle (N) – when two gradients meet at each other and forms an angle. o Case 1: When upward gradient GEOMETRIC DESIGN mees a flat gradient. - Involves creating the physical layout of the o Case 2: When upward gradient railway tracks to ensure safe, efficient, meets another upward gradient. and comfortable transportation. It o Case 3: When upward gradient includes determining the alignment, meets downward gradient. grade, curvature, and other parameters o Case 4: When downward gradient that define the path of the railway. meets another downward gradient. - Components: o Horizontal Alignment – Includes straight sections, curves, and transition curves. o Vertical Alignment – Includes gradients, grade compensation , and vertical curves. - Design Parameters: o Track Gauge – Distance between the rails. o Super-elevation – Cant or banking of the track Valley Curve o Track Clearances – Space around - It is a vertical curve provided when the the track for safe train movement. gradient is downward. Generally when o Track Bed and Subgrade – vehicle meets downward gradient it Foundation that provides stabiity accelerates more and discomfort arises. and drainage. So, in the design of valley curve in vertical alignment comfort is considered along Gradient with sight distance. - Any departure of track from the level is - it is convex downward and concave known as grade or gradient. An up or upward. rising gradient is one when the track rises in the direction of movement whereas a falling or down gradient is one when the track falls in direction of the movement. - Purpose of providing gradient: Reviewer | SYR NCE_3101 | Highway and Railroad Engineering o To provide a uniform rate of riser all Momentum Gradient to the track. - The gradient on a section which is steeper o To reducethe cost of earthwork. than the ruling gradient acquires sufficient o To reach different stations at momentum to negotiate them are known different elevations etc. as momentum gradient. - For a momentum grade no obstacle like TYPES OF GRADIENT signal etc , Should be provided at critical - The gradients used on railway track can be points. classified into four categories as follow: - In valleys, a falling gradient is sometimes followed by a rising gradient. In such a : Ruling Gradient situation, a train coming down a falling - The steepest gradient allowed on the track gradient acquires good speed and section. It determines the max load that momentum, which gives additional the locomotive can haul that section. The kinetic energy to the train and allows it to steep gradient needs more powerful negotiate gradients steeper than the ruling locomotives, smaller train loads, lower gradient. speed, resulting in costly hauling. o In sections with momentum - As a rule rising gradients should be gradients there are no obstacles followed by falling gradients. With this provided in the form of signals, arrangement, the amount of energy used etc., which may bring the train to a up in climbing is saved in descending. critical juncture. o In plains: 1 in 150 to 1 in 200 o In hilly regions: 1 in 100 to 1 in 150 Gradient at Station Yards - At stations gradient are provided Pusher Gradient sufficient low due to the following reason: - As stated above a ruling gradient limits the o To prevent movement of standing maximum weight of a train which can be vehicles on the track due to the hauled over the section by a locomotive. effect of gravity combined with a - If the ruling gradient is so severe on a strong wind or gentle push etc. section that it needs the help of an extra o To prevent additional resistance engine to pull the same load then this due to grade on the starting gradient is known as the pusher of helper vehicles which is about twice at the gradient. start than a vehicle in motion. - In Darjeeling Railways 1 in 37 pusher - On Indian Railways, the maximum gradient is used on Western Ghat BG gradient permitted is 1 in 400 in station Track. yards while in station yards a gradient of 1 in 100 is recommended. Reviewer | SYR NCE_3101 | Highway and Railroad Engineering Reviewer | SYR NCE_3101 | Highway and Railroad Engineering centers at the highest level of service MODULE 4 possible. - Collector – A collector road or distributor CRITERION ON DESIGNING A HIGHWAY AND A road is a low to moderate- capacity road RAILWAY which serves to move traffic from local streets to arterial roads. DESIGN SPEED - Local – A street that is primarily used to - The target speed at which drivers are gain access to the property bordering it. It intended to travel on a street, and not, as often misused, the maximum operating speed. - According to AASHO, Design speed is maximum safe speed that can be maintained over a specified section of highway when conditions are so favorable that the design features of the highway governs. - Factors affecting design speed: o Type of road o Topography of road o Type of intensity of traffic - Generally, the design speeds of highways are chosen by administrative decision. Consequently, the design speed for a particular type of highway will vary from runs parallel to an expressway and allows country to country. local traffic to gain access to property. Ranges for Design Speed ROAD SHOULDER - Freeway – A divided major roadway with - Road shoulder or verge is defined as that full control of access and with no portion of the road-way between the edge crossings at grade. This definition applies of the traffic lane and the edge of the to toll as well as non-toll roads. ditch, gutters, curb or side slope. AASHTO - Arterial – An arterial road, or arterial requires that its usable pavement width thoroughfare, is a high-capacity urban shall be strong enough to support a road. The primary function of an arterial vehicle. road is to deliver traffic from collector - Importance of Road Shoulders: roads to freeways, and between urban Reviewer | SYR NCE_3101 | Highway and Railroad Engineering o serves as a place for vehicles to - Designers create drawings called cut and stop when disabled, or for some fill diagrams. These diagrams illustrate other purposes. all the areas where cut or fill are required o Shoulder should be continuous along the full length of the Reasons for Creating Fills roadway. It also adds structural - Reduction of grade along a route or strength to the road pavement. elevation of the route above water o Shoulder increases the horizontal - Swampy ground sight distance on curves. - Areas where snow drifts frequently collect and used to cover tree stumps, rocks, or CUT OR FILL SLOPES unstable soil. - The lateral slopes of a highway geomtery are sometimes called FILLS or CUTS Fill Diagrams where these techniques have been used - 2 Dimensional Diagrams to create them. Known as excavation and - 3 Dimensional Diagrams embankment. - Smaller Scale Projects – With limited cut - It’s a process procedure at construction and fill needs may not require more than sites to level slopes and create cuttings, 2-dimensional diagrams. canals, and embankments by removing - Larger and more Expensive – Will usually large masses of dirt and stone from one require the accuracy provided by 3- point and using it as a fill in another. dimensional diagrams. - Fill – Earth that is brought into an area is considered “fill”or embankment earth. METHODS TO CALCULATE CUT OR FILL - Cut – Earth that is removed from an area VALUES is considered “cut” or excavated earth. Cross-Section Method - Sections are drawn at equal intervals through the project. For each section line, the cut area and the fill area is determined. - Project planners use detailed and intelligent cut and fill maps to avoid such problems, providing exhaustive plants to help guide excavation teams to the most efficient use of mass and labor. Reviewer | SYR NCE_3101 | Highway and Railroad Engineering - The volume between two sections is - Types of Lanes: determined as the average area of the two o Traffic Lane or Travel Lane sections multiplied by the distence o Through Lane or Thru Lane between them. By adding together, the o Express Lane volumes between all of the sections the o Dedicated Lanes total cut and fill volumes are obtained. - The number of lanes in a segment of the highway is determined from the estimated Grid Method traffic volume for the design year (AADT) - The average cut or fill depths are and highway lane capacity at epected determined for each cell in the grid. level of service. AASHTO policies accept a - From these depths the volumes of each dually divided 16 lanes roadway with four grid cell can be calculated, and by adding lanes in each direction for an inner the cell volumes together the total cut and freeway and four more lanes in each fill volumes are obtained direction on the outside. There are some instances where a reversible lane is located at the center of freeways with unbalanced heavy traffic flow. - Design standards also help to determine the actual alignment of the road by specifying, for each design speed, the minimum radius of horizontal curves, the maximum vertical gradient, the clearnace Automated Method under bridges, and the distance a driver - Automated systems are often use more must be able to see the pavement ahead sophisticated calculation methods, such in order to stop or turn aside. as the triangular prism method. All the - Lane markings are mostly lines painted on features of both surfaces will be the road by a road marking machine, represented in the calculations. NUMBER OF LANES - A lane is part of carriageway that is designated to be used by a single line of vehicles to control and guide drivers and reduce traffic conflicts. - Most public roads (highways) have at least two lanes, one for traffic in each direction, separated by lane markings. Reviewer | SYR NCE_3101 | Highway and Railroad Engineering which can adjust the marking widths concrete barrier or a landscaped island, is according to the lane type. recommended for all new or rebuilt multi- lane highways. HIGHWAY MEDIAN Median MEDIAN OPENINGS - Medians are used to separate lanes of - No median opening traffic moving in opposite directions. - Median crossover without left turn bay - They can be depressed, raised, or flush - Median crossover with a left turn bay with the road surface. - Directional median opening crossover - Medians are required on the following - Two-way left turn lane types of roads: o Freeways o Any street or highway, rural or urban, with 4 or more travel lanes and a design speed of 40 mph or higher. - The type and extent of median separation depend on: o Design speed MEDIAN WIDTH o Traffic volume - The general range of median widths is o Adjacent land use from a min. 6 ft to a desirable dimension o Frequency of access 84 ft or more on freeways and rural areas, - Urban Land Service Highways TYPE OF ROAD MEDIAN o 32 feet wide to accommodate Transversable future widening (12-foot lane, 3- - A median designed to allow vehicles to foot shoulder in each direction, 2- easily enter or cross over it includes foot median concrete barrier curb). options like painted medians and o 16 feet wide where no future continuous two-way left-turn lanes. widening is anticipated. - Types Of Transversable Median: - Rural Land Service Highways o Raised Median o 46 feet wide for future 12-foot lane o Flushed Median and 5-foot shoulder in each o Depressed Median direction with a 12-foot grass median. Non-Transversable o 36 feet wide for future 12-foot lane - A physical barrier on the road that divides and 5-foot shoulder in each traffic moving in opposite directions, like a Reviewer | SYR NCE_3101 | Highway and Railroad Engineering direction with a 2-foot median - Width of Formation concrete barrier curb. - Height of Embankment o Grass median may have sloping - Side Slopes curb on both sides. - Drainage System - Future Extension ADVANTAGES OF MEDIANS - Effective means of reducing headlight STOPPING AND PASSING SIGHT DISTANCES glares, conflicts and accident between SIGHT DISTANCE opposing streams of traffic. - is the length of road ahead visible to a - Median offer refuge between opposing driver, which is critical for the safe and traffic stream of cross traffic and efficient operation of vehicles on a pedestrians could traverse each stream at roadway. separate maneuvers. - Provides available space for left turn STOPPING SIGHT DISTANCE (SSD) lanes. - To allow drivers to perceive, react, and - Making smooth and safe turning operation safely stop. a minimum stopping sight because it clears the through lanes and distance must be available. increase road cap - Stopping sight distance is defined as the sum of two distances. RIGHT OF WAY - A right-of-way (ROW) is a right to make a 2 Components of Stopping Sight way over a piece of land, usually to and Distance from another piece of land. - Reaction Distance - how far your car - A right of way is a type of easement travels in the time it takes the driver to granted or reserved over the land for react to a hazard and step on the brake. transportation purposes, such as a - Braking Distance - is how far your car highway, public footpath, rail transport, travels from the time the brakes are canal, as well as electrical transmission applied until it comes to a complete stop. lines, oil and gas pipelines. - RoW is the area of the road acquired for Primary Stopping Sight Distance Factors: carriages way + other necessities + future - The determination of stopping sight extension, along its alignment. Good distance requires the definition and practice is to acquire RoW wide enough to consideration of seven design variables: accommodate the ultimate development o Perception-reaction time and all components of the road. o Driver eye height o Object height FACTORS AFFECTING RIGHT OF WAY o Vehicle operating speed Reviewer | SYR NCE_3101 | Highway and Railroad Engineering o Pavement coefficient of friction - Excavation o Deceleration rates o Roadway grade Stopping Sight Distance Formula: - Embankment - Subgrade Preparation - Base Layer Construction - Surface Layer Construction PASSING SIGHT DISTANCE (PSD) - Minimum sight distance required on a two-lane, two-way highway that will permit a driver to complete a passing maneuver without colliding with an opposing vehicle and without cutting off the passed vehicle 5 Passing Sight Distance Factors: - Velocities of the passing vehicle passed vehicle and of the vehicle coming in the opposite direction. - Spacing between vehicles, which in-turn depends on the speed - Skill and reaction time of the driver - Rate of the acceleration of passing vehicle - Gradient of the road Minimum Passing Sight Distance Formula STEPS IN CONSTRUCTING OF ROADBEDS - Clearing and Grubbing Reviewer | SYR