Traffic Engineering - PDF

TRAFFIC ENGINEERING: TRAFFIC CHARACTERISTICS – TRAFFIC STUDIES SPEED, VOLUME, SPEED AND DELAY, ORIGIN DESTINATION, PARKING AND ACCIDENT STUDIES; CAPACITY OF URBAN ROADS AND HIGHWAYS; TRAFFIC OPERATION REGULATION AND CONTROL; DESIGN OF INTERSECTIONS AT GRADE AND GRADE SEPA...

TRAFFIC ENGINEERING: TRAFFIC CHARACTERISTICS – TRAFFIC STUDIES SPEED, VOLUME, SPEED AND DELAY, ORIGIN DESTINATION, PARKING AND ACCIDENT STUDIES; CAPACITY OF URBAN ROADS AND HIGHWAYS; TRAFFIC OPERATION REGULATION AND CONTROL; DESIGN OF INTERSECTIONS AT GRADE AND GRADE SEPARATED TOPIC  Traffic Engineering s.  Traffic Engineering Traffic engineering is a branch of civil engineering that uses engineering techniques to achieve the safe and efficient movement of people and goods on roadways. It focuses mainly on research for safe and efficient traffic flow, such as road geometry, sidewalks and crosswalks, cycling infrastructure, traffic signs, road surface markings and traffic lights.  IMPORTANCE OF TRAFFIC ENGINEERING 0 02 03 Safety Reduction of Urban 1 Improvemen Congestion Planning and t Growth Management  Safety Importance Traffic engineering helps reduce accidents by designing safer roads, intersections, and pedestrian pathways. It incorporates safety measures like traffic signals, road signs, and appropriate speed limits, and ensures that road designs minimize potential hazards.  Reduction of Congestion Efficient traffic engineering minimizes traffic congestion, which reduces travel delays, fuel consumption, and vehicle emissions. By analyzing traffic patterns and optimizing road layouts, intersections, and signal timing, engineers can keep traffic flowing smoothly, even during peak hours  Urban Planning and Growth Management Traffic engineering supports urban planning by designing infrastructure that accommodates current needs while planning for future population growth. Properly engineered traffic systems can facilitate orderly urban expansion and the development of sustainable communities. Responsibiliti es of Traffic Engineers  Traffic Engineering Flows Designing Road Road Safety and Intersection Layouts Traffic Control Data Collection Devices and Analysis Traffic Flows Management Analyzing Traffic Patterns - Study and monitor traffic patterns, vehicle flows, pedestrian activity, and road usage to identify areas with congestion or safety concerns. Improving Traffic Flow - Develop strategies to manage and improve traffic flow, such as optimizing signal timings, road widening, or implementing traffic control measures Road Safety Accident Prevention - Identify accident-prone areas and design solutions to reduce crash frequency and severity, such as installing traffic signals, speed humps, or guardrails. Safety Audits - Conduct safety audits of existing roads and intersections to ensure they comply with safety standards and make necessary improvements. Pedestrian and Cyclist Safety - Ensure that roads are safe for all users, including pedestrians and cyclists, by designing crosswalks, bike lanes, and safe walkways.  Designing Road and Intersection Layouts Road Design - Design roads that balance vehicle capacity, safety, and environmental factors. This includes planning for appropriate lane widths, curves, grades, and shoulders. Intersection Design - Plan and design intersections, roundabouts, or other traffic nodes to minimize congestion and delays while improving safety for both vehicles and pedestrians. Signal Systems - Design traffic signal systems that optimize vehicle movement and reduce delays while ensuring pedestrian safety. Traffic Control Devices Implementing Signs and Signals - Plan, install, and manage traffic control devices such as stop signs, speed limits, traffic signals, road markings, and lane signs. Maintaining Devices - Ensure proper functioning of traffic signals, signs, and road markings, and carry out regular maintenance to avoid operational disruptions. Data Collection and Analysis Traffic Surveys and Studies - Conduct traffic studies and surveys, including traffic counts, speed studies, and accident reports, to gather data on current conditions and predict future traffic trends. Modeling and Simulation - Use traffic modeling and simulation software to analyze the impact of proposed changes on traffic flow and to predict how new developments or policies will affect congestion and safety.  TRAFFIC CHARACTERISTICS Five critical components that interact in a traffic system: Road Users Vehicles Streets and Traffic control highways devices The general environment Road User Characteristics The human element is involved in all actions of the road user either as pedestrian, cyclist, cart driver or motorist. The physical, mental and emotional characteristics of human beings effect their ability to operate motor vehicle safely or to service as a pedestrian. 4 Characterisctics 1. Physical 2. Mental 3. Psychological and 4. Environmental  Physical Characteristics The permanent characteristics are the vision, hearing, strength and the general reaction to traffic situations. Vision plays the most important of all these. These include the acuity vision, peripheral vision and eye movement; glare vision, glare recovery and depth judgment. Hearing helps drivers in a way, though it is more important for pedestrians and cyclists. The reaction to traffic situation depends on the time required to perceive and understand the traffic situation and to take the appropriate action. The temporary physical characteristics of the road affecting their efficiency are fatigue, alcohol or drugs and illness. All these reduce alertness and increase the reaction time and also affect quality of judgment in some situations.  Mental Characteristics Knowledge, skill, intelligence, experience and literacy can affect the road user characteristics. Knowledge of the vehicle characteristics, traffic behavior, driving practice, rules of road and psychology of road users will be quite useful for safe traffic operations. Reactions to certain traffic situations become more spontaneous with experience. Understanding the traffic regulation and special instruction and timely action depends on intelligence and literacy. Gallery What can you say about your projects? Share it here!  Psychological factors These affect reaction to traffic situations of road users to a great extent. The emotional factors such as attentiveness, fear, anger, superstition, impatience, general attitude towards traffic and regulations and maturity also comes under this. Distractions by non- traffic events and worries reduce attentiveness to traffic situations. Dangerous actions are likely due to impatience. Some road users do not pay due regard to the traffic regulations and do not have the right attitude towards the traffic. Environmental Factors The various environmental conditions affecting the behavior of road users are traffic stream characteristics, facilities to the traffic, atmospheric conditions and the locality. The traffic stream may consist of mixed traffic or heavy traffic whereas the facilities to overtake for faster vehicles may be limited.  VEHICULAR CHARACTERISTICS It is quite important to study the various vehicular characteristics which effect the design and traffic performance because it is possible to design a road for any vehicle but not for an indefinite vehicle. The basic criterion of highway engineering is to cater for the needs of existing and anticipated traffic. It will not be economically feasible to keep on increasing the geometric standards and thickness of pavements from time to time to meet the needs of a few vehicles whose dimensions and weight are increased. The various vehicular characteristics affecting the road design may be classified as static and dynamic characteristic of the vehicle.  Static Characteristics Vehicle characteristics that affect the road design are the dimensions, weight and maximum turning angle. Dynamic Characteristics Vehicle characteristics that affect the road design are speed, acceleration and breaking characteristics and some aspects of vehicle body design. Vehicle Categories ➔ Passenger Type ➔ Bus ➔ Trucks ➔ Recreational Vehicles  Road Characteristics Road Surface The type of pavement is determined by the volume and composition of traffic, the availability of materials, and available funds. Some of the factors relating to road surface like road roughness, tire wear, tractive resistance, noise, light reflection, electrostatic properties etc. should be given special attention in the design, construction and maintenance of highways for their safe and economical operation.  Lightning Illumination is used to illuminate the physical features of the road way and to aid in the driving task. A luminaire is a complete lighting device that distributes light into patterns much as a garden hose nozzle distributes water. Proper distribution of the light flux from luminaires is one of the essential factors in efficient roadway lighting. It is important that roadway lighting be planned on the basis of many traffic information such as night vehicular traffic, pedestrian volumes and accident experience  Roughness This is one of the main factors that an engineer should give importance during the design, construction, and maintenance of a highway system. Drivers tend to seek smoother surface when given a choice. On four- lane highways where the texture of the surface of the inner-lane is rougher than that of the outside lane, passing vehicles tend to return to the outside lane after execution of the passing maneuver. Shoulders or even speed-change lanes may be deliberately roughened as a means of delineation.  Pavement Colors When the pavements are light colored (for example, cement concrete pavements) there is better visibility during day time whereas during night dark colored pavements like bituminous pavements provide more visibility. Contrasting pavements may be used to indicate preferential use of traffic lanes. A driver tends to follow the same pavement color having driven some distance on a light or dark surface, he expects to remain on a surface of that same color until he arrives a major junction point.  Night Visibility Since most accidents occur at night because of reduced visibility, the traffic designer must strive to improve night time visibility in every way he can. An important factor is the amount of light which is reflected by the road surface to the drivers' eyes. Glare caused by the reflection of oncoming vehicles is negligible on a dry pavement but is an important factor when the pavement is wet.  Geometric Aspects The roadway elements such as pavement slope, gradient, right of way etc., affect transportation in various ways. Central portion of the pavement is slightly raised and is sloped to either sides so as to prevent the ponding of water on the road surface. This will deteriorate the riding quality since the pavement will be subjected to many failures like potholes etc. Traffic Studies and Analysis Project Proposal Traffic studies and analysis are crucial components of highway and railroad engineering, as they provide essential insights into the functioning and efficiency of transportation systems. This discussion will delve into various aspects of traffic studies and analysis, including speed, volume, speed and delay, origin-destination studies, parking studies, accident studies, and the capacity of urban roads and highways.  SPEED Speed is the rate of travel expressed in kmph or m/s. Over a particular route, the actual speed of vehicle may vary. Speed of vehicle depends upon several factors such as geometric features, traffic conditions, time, place, driver and environment.  Types of Speed AVERAGE SPOT SPEED SPEED RUNNING JOURNEY SPEED SPEED SPOT SPEED – refers to an instantaneous speed of vehicle at particular instant of time or section of road. It is measured by enoscope, pressure contact tube, loop detector. AVERAGE SPEED Speed is the rate of travel expressed in kmph or m/s. Over a particular route, the actual speed of vehicle may vary. Speed of vehicle depends upon several factors such as geometric features, traffic conditions, time, place, driver and environment. Two Types of Average Speed SPOT SPEED AVERAGE SPEED RUNNING SPEED -the average speed maintained by a vehicle over a given course while the vehicle is in motion. Running Speed = length of course / running time (Running Time = Journey Time – Delay) Running Speed = length of course / (Journey Time – Delay) JOURNEY SPEED -also known as Overall Travel Speed. It is the effective speed between two points. It is the distance between two points divided by total time taken by the vehicle to complete the journey, including all delays. Journey Speed = Distance / Total Journey Time (including delays) TRAFFIC VOLUME Traffic Volume is the number of vehicles crossing a section of road per unit time at any selected period. It is used as a quantity measure of flow: the commonly used units are vehicles/day or vehicles/hour.  Object and Uses of Traffic Volume Study It is generally accepted as -It is used in planning, -It is used in analysis of - Pedestrian traffic volume a true measure of the traffic operation and traffic patterns and trends. study is used for planning relative importance of control of existing facilities sidewalk, cross walks, roads and in deciding the and also for planning the -Useful in structural subway, and pedestrian priority for improvement new facilities. design of pavement. signals. and expansion.  MAIN METHOD IN COUNTING MANUAL COUNTING AUTOMATIC COUNTING METHOD METHOD MANUAL COUNTING METHOD – counts are typically used to gather data for determination of vehicle classification, turning movements, direction of travel, pedestrian movements, or vehicles occupancy. Most applications of manual counts require small samples of data at any given location. Manual counts are sometimes uses when the effort and expense of automated equipment are not justified. These are necessary when automatic equipment are not available. A Manual Classified Count (MCC) involves counting all the vehicles passing a selected location on a road for a pre-determined period of time. The count records individual vehicles by categories (i.e. a truck or car) and the direction they are traveling in. Advantages of Manual Disadvantages of Counting Method Manual Counting Details such as vehicle classification and number of occupants Method can be obtained. Records turning movement data of vehicles at intersections. Counts of remote areas is possible by Analyzing traffic characteristics in unusual conditions such as automatic devices. adverse weather conditions, traffic breakdowns, temporary Not practicable to have manual count for 24 closure of any lane of highway etc. hours of the day and throughout the year. Comparatively cheaper method of counting Data accumulated by manual method are easy to analyze. AUTOMATIC COUNTING METHOD In this method, vehicles are counted automatically without any human involvement. The automatic count method provides a means for gathering large amounts of traffic data. Automatic counts are usually taken in 1-hour interval for each 24-hour period. The counts may extend for a week, month, or year. When the counts are recorded for each 24-hour time period, the peak flow period can be identified. Automatic counts are recorded using one of the three methods: Automatic counts are records using one of the three methods: PORTABLE PERMANENT COUNTER COUNTER VIDEOTAPE PORTABLE COUNTERS – is a form of manual observation. It serves the same purpose as manual counts but with automatic counting equipment. The period of data collection using this method is usually longer than when using the manual counts. It is mainly used for 24-hour counts. Pneumatic road tubes are used to conduct this method of automatic counts.  PERMANENT COUNTERS – are used when long-term counts are to be conducted. The counts could be performed every day for a year or more. The data collected may be used to monitor and evaluate traffic volumes and trends over a long period of time. VIDEOTAPE – observers can record count data by videotaping traffic. Traffic volumes can be counted by viewing videotapes record with a camera at collection site. A digital clock in the video image can prove useful in noting time intervals.  Speed and Delay, Origin Destination, Parking and Accident ESPIÑA Studies  Speed And Speed and delay studies give the running speeds, overall speeds, fluctuations in Delay speed and delay between two stations of a road spaced far apart. They also give the information such as amount, location, duration, frequency, and causes of the delay in the traffic stream.Various methods to carry out speed and delay survey are: One Two FLOATING CAR LICENSE PLATE METHOD METHOD Three Four INTERVIEW PHOTOGRAPHY AND TECHNIQUE VIDEOGRAPHY  FLOATING CAR It synchronized stopwatches or voice recording METHOD equipment are used. Observers are stationed at the entrance and exit of a test section where information of the travel time is required. The timing and vehicle numbers are noted by the observers of the selected sample FLOATING CAR METHOD FORMULA where: t = average journey time in minute q= flow of vehicle(average volume) in one Traffic direction of the stream Time na = average number of vehicles counted in the direction of the Stream when the rest vehicle travels in the opposite directions ny = the average no. of vehicles overtaking the test vehicle minus the no. of vehicles overtaken when the test is in the direction of "q" Traffic tw = average journey time, in minute when the test Flow vehicle is travelling with the stream 'q ta = average journey time, in minute when test vehicle is running against the stream 'q  Sample A traffic surveyor analyze a 4-kilometer stretch of Solution: Problem road. The following data has been collected; - Time with the traffic flow (tw): 8 minutes Calculate Traffic Flow (q) - Number of vehicles overtaken (no): 3 q = (na + ny)/(ta + tw) - Number of vehicles that passed the test car (ny): 2 q = (10 + 2)/(7 + 8) = 12/15 = 0.8 (vehicles per minute) - Number of vehicles moving in the opposite direction (na): 10 Now, multiply by 60 to convert it to vehicles per hour: - Time moving against the traffic flow (ta): 7 minutes q = 0.8 × 60 = 48 ( vehicles per hour) We are asked to: 1. Determine the travel time (t) using the floating Calculate Travel Time (t) car method. 2. Estimate the traffic flow (q). t = tw - (ny/q) t = 8 - (2/48) = 8 - 0.0417 = 7.9583(minutes) t = 7.96(minutes) - The "travel time" (t) is approximately 7.96 minutes. - The "traffic flow" (q) is 48 vehicles per hour.  LICENSE PLATE It synchronized stopwatches or voice recording equipment are used. METHOD Observers are stationed at the entrance and exit of a test section where information of the travel time is required. The timing and vehicle numbers are noted by the observers of the selected sample Method for speed and delay By Interview the work can be completed in a short time by interviewing and collecting details from the Intervie road user spot. However, the data collected may not provide with all the details correctly. w Techniqu e Photograph By Photography and Videography, this is useful for studying short test section like intersection. y and Videograph y  Origin In transportation study, it is often necessary to know the exact origin and destination of the trips. The information yielded by Destination Origin-Destination survey includes land-use of the zones of the origin and destination, household characteristics of the trip making family, time of the day when journeys are made, trip purpose and mode of travel.  Origin Origin-Destination studies are an important tool for transportation Destination professionals. OD studies are conducted to understand the pattern of the movement of persons and goods in a particular area of interest during a particular period of time. Origin Defined as the place where the trip begins Destination Defined as the place where the trip ends Parking Studies Parking studies are conducted to inform decisions about land use, transportation infrastructure, and parking management. Parking Effects Congestion Accident parking takes considerable careless maneuvering of parking street space leading to the leads to accidents which are lowering of the road capacity referred to as parking accidents. Obstruction to Effect on Firefighting cause pollution to the Environment environment because stopping Operations parked vehicles may and starting of vehicles while obstruct the movement parking and unpacking results of firefighting vehicles. in noise and fumes. Parking System On-Street Parking Means the vehicles are parked on the sides of the street itself. The classification is based on the angle in which the vehicles are parked with respect to the road alignment. Common Types of On-Street Parking Parallel Parking – the vehicles are parked along the length of the road. 30° Parking – the vehicles are parked at 30° with respect to the road alignment. 45° Parking – as the angle of parking it increases the number of vehicles that can be parked. 60° Parking – the vehicles are parked at sixty-degree to the direction of road. Right Angle (90°) Parking – in right angle parking, the vehicles are parked perpendicular to the direction of the road.  0 Parallel 1 Parking  0 30° Parking 2  0 45° Parking 3  0 60° Parking 4  0 RIGHT 5 ANGLE(90°) Parking Off-Parking System In may urban centers, some areas are exclusively allotted for parking which will be at some distance away from the mainstream of traffic. Such a parking is referred to as off-street parking.  Accident Studies One Two Elaborate on what you Elaborate on what you want to discuss. want to discuss. Three Four Elaborate on what you Elaborate on what you want to discuss. want to discuss.  Accident Studies Road accident cannot totally prevented, but by suitable traffic engineering and management measures, the accident rate can be decreased considerably The various objectives of the accident studies may be listed as: To study the cause of accident and to suggest corrective treatment at potential location and to evaluate proposed design To carry out studies before and after for improvement To make financial computations and to give economic justifications for the improvements suggested by the traffic engineer.  Causes of Accident badly located gate of level The road users The vehicles advertised crossing boards,  Causes of Accident The road and Road design incorrect signs Environmental its condition and signals factors  Capacity of Urban Roads and Highways Capacity refers to the maximum traffic flow that can be accommodated on a roadway during a specified time period under prevailing roadway, traffic, and control conditions.  Urban Road Capacity Urban road capacity refers to the maximum number of vehicles that a road can accommodate in a given time period under specific conditions. It’s influenced by factors like road design, traffic signals, vehicle types, and traffic flow characteristics  Key factors influencing urban road capacity include: Lane Width and Traffic Flow: Number: Different flow types (free Wider and more lanes flow, congested flow) typically increase capacity. affect capacity. Traffic Composition: Intersection Design: The types of vehicles using Efficient intersections the road (cars, trucks, (like roundabouts) can buses) impact capacity. enhance capacity. Environmental Factors: Weather conditions, road conditions, and urban infrastructure (like public transit) can impact capacity.  Highway Capacity Highway Capacity is a key concept in transportation engineering that refers to the maximum number of vehicles that can pass a specific point on a roadway within a designated timeframe, usually measured in vehicles per hour.  The Highway Capacity Manual (HCM) established a framework for understanding highway capacity, introducing three distinct categories of capacity as defined by O.K. Normann: 0 02 03 Basic Possible Practical 1 Capacity Capacity Capacity  Basic capacity is the theoretical maximum Basic 01 number of vehicles that can traverse a specific point on a lane or roadway in one hour, Capacity assuming ideal roadway and traffic conditions. Possible capacity is the maximum number of Possibl vehicles that can pass a specific point on a 02 e Capacit lane or roadway during one hour, considering the prevailing roadway and traffic conditions. y Practical capacity is the maximum number of Practica 03 vehicles that can pass a point on a lane or roadway in one hour while maintaining l acceptable levels of traffic density, delay, and Capacit safety. y Importance of Urban Road and Highways Capacity Traffic Flow: Reduces congestion and travel times. Economic Efficiency: Facilitates goods movement, boosting productivity. Safety: Lowers accident rates with smoother traffic. Environmental Impact: Decreases emissions by reducing idling. Public Transport Integration: Enhances efficiency of public transit systems. Urban Planning: Guides sustainable development and zoning. Emergency Response: Ensures quick access for emergency services. Quality of Life: Reduces travel stress, allowing more leisure time.  Road Maintenance and Rehabilitation Project Proposal  7.4 TRAFFIC OPERATION, REGULATION AND CONTROL  TRAFFIC OPERATION 1. Traffic Flow Management: Techniques to optimize the movement of vehicles, including signal timing adjustments and real-time traffic monitoring. 2. Signal Control: The use of traffic signals to regulate when vehicles and pedestrians can move, often adjusted based on traffic volume and time of day. 3. Incident Management: Systems and protocols for responding to accidents or breakdowns, including quick clearance and detour planning. 4. Roadway Design: Planning and designing roadways to facilitate safe and efficient traffic flow, including lane configurations and signage. 5. Traffic Enforcement: The role of law enforcement is ensuring compliance with traffic laws and regulations, including monitoring speed limits and enforcing parking rules. 6. Public Transportation Coordination: Integrating bus and transit services with road traffic to enhance overall mobility and reduce congestion.  TRAFFIC REGULATION AND CONTROL 1. Traffic Signs and Signals Regulatory Signs: Indicate laws (e.g., speed limits, no parking). Warning Signs: Alert drivers to potential hazards (e.g., sharp turns, pedestrian crossings). Guide Signs: Provide directional and informational assistance (e.g., highway exits, services). 2. Traffic Laws Enforced by law enforcement agencies, these laws govern driver behavior, including speed limits, right-of-way rules, and DUI regulations. 3. Traffic Control Devices Traffic Lights: Control the flow of vehicles and pedestrians at intersections. Roundabouts: Manage traffic flow without the need for signals, reducing delays and accidents. 4. Road Markings Lines, symbols, and colors on the road surface help guide drivers and indicate lane usage, stopping points, and other critical information. 5. Speed Control Measures Techniques like speed bumps, traffic calming measures, and enforcement cameras to encourage adherence to speed limits.  DESIGN OF INTERSECTION ROADS AT-GRADE INTERSECTIONS At-grade intersections occur when two or more roads cross at the same elevation. They are the most common type of intersection and include signalized and unsignalized configurations. The following are the three basic forms of intersections at grade: 1. Unchannelised and Unflared intersections (Type BA) This type of intersection is normally adequate where minor roads meet and where major road intersects with a minor road. In urban areas, many intersections remain unchannelised, sometimes for economic reasons, even though the volume of turning traffic may otherwise need special treatment. In such cases, traffic is often controlled by traffic signals or regulatory signs, such as STOP or GIVE WAY signs, on minor roads. 2. Unchannelised and flared intersections (Type AU) Simple unchannelised intersections may be flared to provide additional through lanes or auxiliary lanes, such as speed- change lanes or passing lanes Speed change lanes allow left or right- turning vehicles to reduce or increase speed when leaving or entering the through road without aversely the speed of through traffic. Passing lanes permit through vehicles to pass on the left side of another vehicle waiting to complete a right turn at an intersection. 3. Channelised intersections (Type CH) A channelised intersection is one where paths of travel for various movements are separated and delineated. Raised traffic islands, raised markers, painting markings and safety bars can be used for channelisation. A roundabout is a channelised intersection where traffic moves clockwise around a central island. GRADE-SEPARATED INTERSECTIONS OR INTERCHANGES - Also known as grade-separated intersections, the roads are separated and constructed at different elevations, obviating the need for crossing at the same elevation. Grade separation may be achieved by the construction of an over-bridge or an under-bridge. TWO TYPES OF GRADE-SEPARATED INTERSECTIONS (a) Grade-Separated Junction without Interchange: - This is a system wherein the traffic at different levels moves separately without a provision for an interchange between them; the separation is achieved by means of an over-bridge, fly-over, or an underpass. (b) Grade-Separated Junction with Interchange: - This is a system wherein the traffic, besides moving separately in streams at different levels, can get interchanged from one stream to another via an interchange facility. A proper design of the system facilitates an orderly and safe movement of traffic. This is a high-end facility for large volumes of traffic on two or more roads involved with a heavy proportion of turning traffic.  Interchanges can be considered on the basis of the number of legs served by the intersection and classified as three-leg, four-leg, and multi-leg intersections with the following sub­divisions: (1) Three-Leg Interchange: A T-interchange is one in which one of the intersection legs meets a highway approximately at right angles, but does not cross it, and it is provided with an interchange facility. A Y-interchange is similar to a T-interchange, but for the intersection angle which is acute or obtuse (2) Four-Leg Interchange: This is an interchange with four intersecting legs. The simplest of these is the diamond interchange. When the crossing involves major and minor roads in an urban area, a diamond interchange is popular. (3) Half Clover-Leaf Interchange: Also called a partial clover-leaf interchange, this type is suitable when a major road crosses a minor one with not more than two lanes (4) Clover-Leaf Interchange: The clover-leaf interchange is four-leg interchange which fulfills all the requirements of turning traffic with simple traffic manoeuvres. This is perhaps the best solution when two highways with heavy traffic volume and high speed intersect each other (5) Grade-Separated Rotary Interchange: This can serve as a four-leg interchange or as a multi-leg interchange; a typical form of the latter. (6) irectional Interchange: A directional interchange facilitates direct or semi-direct connections for major right-turning movements; but these interchanges are rather complex and require multi-level support structures.