CE 2219 Principles of Transportation Engineering PDF

CE 2219 Principles of Transportation Engineering INTRODUCTION TRANSPORTATION ENGINEERING  Institute of Transportation Engineers, 1987  The application of technological and scientific principles to the planning, functional design, operation, and management of facilities for a...

CE 2219 Principles of Transportation Engineering INTRODUCTION TRANSPORTATION ENGINEERING  Institute of Transportation Engineers, 1987  The application of technological and scientific principles to the planning, functional design, operation, and management of facilities for any mode of transportation in order to provide for the safe, rapid, comfortable, convenient, economical, and environmentally compatible movement of people and goods TRAFFIC ENGINEERING  The branch of transportation engineering which deals with planning, geometric design, and traffic operations of roads, streets, and highways, their networks, terminals, abutting lands, and relationships with other modes of transportation  First recognized in the United States in 1921 Milestones in the developing profession of traffic engineering 431341 Tumakbo para free wifi order shawarma 04 07 08 11 15 16 Year Activity 1904 Traffic survey methods were being employed 1907 Pedestrian islands were used in San Francisco 1908 First driver’s license law was adopted 1911 White-painted pavement center lines were first applied 1915 Origin-destination studies and accident spot maps were first used 1916 Speed and delay study was first made by observing traffic from a high building; pedestrian regulation; and “No Left Turns” were prescribed; curb parking was prohibited to facilitate traffic movement Development of traffic signal control Fa Ma IFEF 68 10 22 26 27 28 Year Activity 1868 First traffic signal illuminated by gas in Great Britain 1910 Manually operated semaphore signals 1922 Idea of timing signals for progressive movement 1926 First automatic traffic signals in Great Britain 1927 Earliest known application of time-space diagram for coordination 1928 First traffic-actuated signals INTERDISCIPLINARY BREADTH OF TRANSPORTATION ENGINEERING TRANSPORTATION SYSTEM  Functional system in the context of society as a whole because it provides a service – the movement of goods and people from place to place – that is essential to the functioning of the community as a whole.  A highly developed transportation system makes possible the abundance and variety of goods and the high levels of personal mobility that are hallmarks of a wealthy society. TRANSPORTATION SYSTEM  Consisting of the fixed facilities, the flow entities, and the control system that permit people and goods to overcome the friction of geographical space efficiently in order to participate in a timely manner in some desired activity TRANSPORTATION SYSTEM Fried fish, chicken, order online  Components  Fixed / Physical facilities – physical components of the system that are fixed in space and constitute the network of links (roadway, railway, and pipes) and nodes (intersections, interchanges, terminals, harbors, airports)  Flow entities – units that traverse the fixed facilities, e.g bicycles, vehicles, containers, railroad cars, fleets, vessels, aircrafts  Control system / Operating strategies – consists of vehicular control and flow control; vehicle routing, scheduling, and traffic control  Operating bases and facilities – vehicle maintenance facilities and office spaces  Organizations – classified as facility-oriented organizations (planning designing, constructing, maintaining, and operating fixed facilities) and operating organizations/carriers (operating fleets to provide transportation services) TRANSPORTATION SYSTEM  Human behavior that are affected by transportation  Locomotion (passenger, pedestrian)  Activities (vehicle control, maintenance, community life)  Feelings (comfort, convenience, enjoyment, stress, likes)  Manipulation (modal choice, route selection, vehicle purchase)  Health and safety (accidents, disabilities, fatigue)  Social interaction (privacy, territoriality, conflict, imitation)  Motivation (positive or aversive consequences, potentiation)  Learning (operator training, driver education, merchandising)  Perception (images, mapping, sensory thresholds) TRANSPORTATION SYSTEM  Human behavior that are affected by transportation  Locomotion (passenger, pedestrian)  Activities (vehicle control, maintenance, community life)  Feelings (comfort, convenience, enjoyment, stress, likes)  Manipulation (modal choice, route selection, vehicle purchase)  Health and safety (accidents, disabilities, fatigue)  Social interaction (privacy, territoriality, conflict, imitation)  Motivation (positive or aversive consequences, potentiation)  Learning (operator training, driver education, merchandising)  Perception (images, mapping, sensory thresholds) TRANSPORTATION SYSTEM  Properties of the physical environment that have a direct Sa Cagayan Calayan At Vizcaya impact on human behavior  Spatial organization (shape, scale, definition, bounding surface, internal organization of objects and society, and connections to other spaces and settings)  Circulation and movement (people, goods, and objects used for their movement and the forms of regulating them – corridors, portals, open spaces)  Communication (signs and symbol, behavior, responses and meanings that gives users information and ideas)  Ambience (microclimate, light, sound, and odor – physiological and psychological functioning of the human organism)  Visual Properties (color, shape, and other visual modalities) TRANSPORTATION SYSTEM Rakrakan Sa Aurora Cordon Pati Tuao  Properties of the physical environment that have a direct impact on human behavior  Resources (physical components and amenities of a transportation system – paths, terminals, vehicles – dimensions as the number of lanes or the square footage of the terminals)  Symbolic properties (social values, attitudes, and cultural norms that are represented or expressed by the environment)  Architectonic properties (sensory or aesthetic properties of the environment)  Consequation (strengthens or weakens behavior – costs, risks, and congestion)  Protection (safety factors)  Timing (scheduled cyclical rhythms – daily, hourly, weekly) TRANSPORTATION SYSTEM  Impact of the environment on aspects of human behavior relevant to transportation Social Interaction Health & Safety Human Behavior Manipulation Locomotion Perception Motivation Activities Learning Feelings Environmental Aspects Spatial Organization X X X Circulation & Movement X X X X X Communication X X X X Ambience X X X X X Visual Properties X X Resources X X X X X Symbolic Resources X X X X X Architectural Properties X X X X X X X Consequation X X X X Protection X X Timing X X TRANSPORTATION SYSTEM  Impact of the environment on aspects of human behavior relevant to transportation Impact of environment on human behavior relevant to transpo Safety SSCCCSA Security Convenience Continuity Comfort System coherence Attractiveness MOVEMENT AND TRANSPORTATION  Interaction between activities is manifested by the movement of people, goods, and information  Reason: 1. Complementarity – relative attractiveness between two or more destinations 2. Transferability – the desire to overcome distance; time, money, technology 3. To satisfy demand and supply  MOVEMENT AND TRANSPORTATION  Mode Choice Trips  How people and goods move from an origin to a destination Transportation  Time, speed, efficiency, costs, safety, Land Use Needs convenience  Trip Generation Dictate what transportation facilities Transportation  Land Value Facility will be needed to move traffic Accessibility Land Use / Transportation Cycle EFFECTIVENESS Three Basic Attributes Una Mali Pa 1. Ubiquity / Accessibility 2. Mobility 3. Productivity / Efficiency EFFECTIVENESS Basic Attributes 1. Ubiquity / Accessibility  The amount of accessibility to the system  The cost of getting to and from the mode in question  Directness of the routing between access points  System’s flexibility to handle a variety of traffic conditions 2. Mobility  The quantity of travel that can be handled  Capacity of the system to handle traffic and speed  Line – haul travel time and door – to – door travel time EFFECTIVENESS Three Basic Attributes 3. Productivity  Measure of the total cost or amount of transportation provided per unit time  Product of the volume of goods or passengers carried and distance (ton-miles per year or passenger-kilometers per day) Efficiency  Relationship between the cost of transportation and the productivity of the system  Direct cost: capital and operating costs, and indirect costs comprise adverse impacts and unquantifiable costs, such as safety MODES OF TRANSPORTATION  Four major subsystems 1. Land Transportation 3. Water Transportation a. Highway a. Inland b. Rail b. Coastal c. Ocean 2. Air Transportation 4. Pipelines a. Domestic a. Oil b. International b. Gas c. Other MODES OF TRANSPORTATION  Private Transportation  Not-for-hire services  Private parties  Public Transportation  For-hire services  General public  Contract carriers (services under individual contractual arrangements; taxi, car rentals) Common carriers (offer scheduled service and are open to all members of the public willing to pay the posted fare; mass transit/transportation) MODES OF TRANSPORTATION Mode Classification Scheme Freight Transportation Passenger Transportation Urban Travel Truck (highway) Private vehicles(highway) Transit (highway/rail) Intercity Travel Truck (highway) Private vehicles(highway) Rail Bus (highway) Short (800km) Inland Water Air Bulk Freight Pipeline General Cargo Air Special purpose Conveyor Belt Cable systems TRANSPORTATION GAPS Demands for Speed Depend on Distance Traveled TRANSPORTATION GAPS Theoretical Distance, Time, Transport Speed, Transport Alternative km min km/hr 0.4 5 4.8 Walking 1 6.6 9.1 Bus (town center) 4 10 24 Streetcar or bicycle 10 13.2 45.5 Car (urban or suburban) 40 20 120 Highway 100 26.4 228 Train or Airplane 1000 52.8 1140 Jet Transport Function Concept BASIC CHARACTERISTICS OF MAJOR TRANSPORTATION MODES  TRANSPORTATION POLICYMAKING Investigate and identify the problem Develop problem statement  It encompasses a broad set of policy variables Establish goals and objectives  Planning and development of Establish criteria for design and transportation facilities evaluation generally raises living Design alternative actions standards and enhances the aggregate of community Establish new Collect relevant data value objectives and assumptions, and Test and evaluate (effectiveness and costs add alternatives Question objectives and assumptions NO Satisfied? Yes Suggest appropriate action and decision TRANSPORTATION SYSTEM MODEL Land Labor Inputs Capital Materials Information Vehicles Pavements Activity Tracks Subsystem Right-of-way Individuals and Terminals groups of people Riding involved Other manufacture Driving or natural objects Traffic Physical Control Human Subsystem Subsystem Outputs Movement of people and goods Improvement or deterioration of the physical environment CE 2219 Principles of Transportation Engineering TRANSPORTATION AS A SYSTEM & PHILIPPINE TRANSPORTATION SYSTEM INTRODUCTION Transportation – act or process of moving people or goods from one place to another by land, air, or sea. Transportation System – composed fixed facilities, the flow entities, and the control system that allow for the movement of people and goods from one place to another safely, efficiently and in a timely manner. Taken from: https://www.cicnews.com/wp-content/uploads/2020/05/20200527CBSA TRANSPORTATION AS A SYSTEM (TAAS) Transportation - as - a - system – Combination of existing applications into and development of entirely new systems-based collaborative models. TAAS deals with linking the movement people and goods though the different modes of transportation to the whole network in real time. Connectivity between vehicles, road conditions, traffic signals, and road accidents) Taken from: https://www.qualitymag.com/ext/resources/Issues/2019/April/NDT/autom TRANSPORTATION AS A SYSTEM (TAAS) Today: Vehicle level focus Independent Unconnected Subject to behaviors & decisions Tomorrow: System level focus Connected Automated In concert Across modes Managed behaviors & decisions Agencies working together (energy, safety, mobility) Exploring the untapped transportation system level efficiencies TRANSPORTATION AS A SYSTEM (TAAS) Objectives of TAAS is to have: Multi-modal transport system – passengers and goods Automated and Connected – vehicles and traffic control devices Manage Travel Behavior and Decisions Interagency working group – technical side and political side Taken from: Sarkar, (2016). TAAS, US Department of Energy. TRANSPORTATION AS A SYSTEM (TAAS) efault/files/2021-03/bikebus_sstock.jpe from:https://www.greenbiz.com/sites/d Multi-modal transport system For Passengers – Single journey experience “seamless travel” (bike and train, park and train, park-shuttle-plane) Taken g uploads/2019/08/What-is-Multimodal-T http://www.deniint.com.mk/wp-content/ For Freight – to have a single provide manage 2 or more modes ransportation-1200x756.jpg of transport for the goods. Taken from TRANSPORTATION AS A SYSTEM (TAAS) efault/files/2021-03/bikebus_sstock.jpe Multi-modal transport system from:https://www.greenbiz.com/sites/d Expected Outcomes: Quantify potential energy savings and GHG reductions in urban areas Diminished modal barriers Taken g Passenger and freight uploads/2019/08/What-is-Multimodal-T http://www.deniint.com.mk/wp-content/ Counteract projected growth of freight energy consumption ransportation-1200x756.jpg Leveraging of disparate modal energy intensities Streamline transfers, shift to new Taken from modes, etc. TRANSPORTATION AS A SYSTEM (TAAS) Automated and Connected Vehicles – use Connected and Automated Vehicles (CAVs). Use for Cargo, Deliveries, and Taken from: Sarkar, (2016). TAAS, US Department of Commuting) Energy. https://risingnepaldaily.com/photos/1/giri Traffic Control Devices – real time raj/smart%20traffic.jpg data collection and analyzation to control and manage traffic flow. Taken from TRANSPORTATION AS A SYSTEM (TAAS) Automated and Connected Expected Outcomes: 1. Quantify the energy impact of CAVs 3. Inform policy/research on CAV’s Multi-scale Maximize sustainability impacts Multiple scenarios Different technologies 2. Identify CAV-enabled opportunities Vehicle electrification Lightweighting Powertrain optimization Vehicle utilization Reduced VMT’s TRANSPORTATION AS A SYSTEM (TAAS) Manage Travel Behavior & Decision Deals with mobility decision science – data collection to understand and influence consumer choice and travel behaviors. Example: buying of goods, and ordering of food. TRANSPORTATION AS A SYSTEM (TAAS) Manage Travel Behavior & Decision Expected Outcomes: Enhanced vehicle adoption and choice models Inform holistic policy decisions, vehicle R&D, and infrastructure investments Accelerate PEV adoption Understanding of individual and market behavior Future technologies, policies, and transportation systems TRANSPORTATION AS A SYSTEM (TAAS) Interagency working group The consortium includes: National and Local Government; Government Agencies and Departments; Urban Planners and Engineers, and; Data Scientists. Taken from: https://transitionta.org/wp-content/uploads/2021/05/topics-sidebar-interagency-collaborati on.jpg TRANSPORTATION AS A SYSTEM (TAAS) Taken from: Sarkar, (2016). TAAS, US Department of Energy. PHILIPPINE TRANSPORTATION SYSTEM PHILIPPINE TRANSPORTATION SYSTEM Public Transportation System – In local setting, our dominant mode for road based public transport are Public Utility Jeepneys. According to the report of Land Transportation Franchising Regulatory Board (LTFRB) “Our public transport system is deemed unsafe, unhealthy, unreliable, and uncomfortable” PUBLIC TRANSPORTATION SYSTEM Taken from: LTFRB – State of Public Transport System in the Philippines PUBLIC TRANSPORTATION SYSTEM Taken from: LTFRB – State of Public Transport System in the Philippines PUBLIC TRANSPORTATION SYSTEM Taken from: LTFRB – State of Public Transport System in the Philippines PUBLIC TRANSPORTATION SYSTEM Outcomes of the unplanned Public Transportation System: 1. Widespread competition among various transport modes, overlapping routes; 2. No hierarchy of modes; 3. Low-capacity vehicles in high-demand areas, leading to reduced road capacity, and; 4. Traffic Congestion. PUBLIC TRANSPORTATION SYSTEM 1. Widespread competition among various transport modes, overlapping routes; Taken from: LTFRB – State of Public Transport System in the Philippines PUBLIC TRANSPORTATION SYSTEM 2. No hierarchy of modes Taken from: LTFRB – State of Public Transport System in the Philippines PUBLIC TRANSPORTATION SYSTEM 3. Low-capacity vehicles in high-demand areas, leading to reduced road capacity; Taken from: LTFRB – State of Public Transport System in the Philippines PHILIPPINE TRANSPORTATION SYSTEM The following are the current Subsystem of Transportation in the Philippines: 1. Land Transportation Highway Railway Taken from:https://www.linkedin.com/pulse/land-transporta tion-future-william-jones/ 2. Air Transportation Taken from: https://www.igtsolutions.com/brochures/lan d-transportation-bpo-services/ Domestic International Taken from: https://aviationvoice.com/wp-content/u ploads/2018/07/G.-Ziemelis-The-Futur e-of-Personal-Air-Transportation.jpg PHILIPPINE TRANSPORTATION SYSTEM The following are the current Subsystem of Transportation in the Philippines: 3. Water Transportation Ferry Services Philippine Nautical Highway System (Roll-on/Roll-off Terminal System {RRTS} or RoRo System. Port Terminal for cargo (Freight) PHILIPPINE TRANSPORTATION SYSTEM Highway National, Provincial, and Local Roads Expressways - a high-speed divided highway for through traffic with access partially or fully controlled. NLEX – North Luzon Expressway SLEX – South Luzon Expressway CAVITEX – Manila-Cavite Expressway TPLEX – Tarlac-Pangasinan-La union Expressway CALAX – Cavite-Laguna Expressway SKYWAY STAR – Southern Tagalog Arterial Road SCTEX – Subic-Clark-Tarlac Expressway PHILIPPINE TRANSPORTATION SYSTEM Highway: Expressways in Philippines PHILIPPINE TRANSPORTATION SYSTEM Highway: Expressways in Middle East PHILIPPINE TRANSPORTATION SYSTEM Railways LRT – Light Rail Transit (Line 1 & 2) MRT – Mass Rapid Transit PNR – Philippine National Railway PHILIPPINE TRANSPORTATION SYSTEM Railways LRT – Light Rail Transit MRT – Mass Rapid Transit (3 & 7) PNR – Philippine National Railway PHILIPPINE TRANSPORTATION SYSTEM Railways LRT – Light Rail Transit MRT – Mass Rapid Transit PNR – Philippine National Railway CAPACITY AND LEVEL OF SERVICE Traffic Engineers rely on capacity and LOS analyses to determine the width and number of lanes when planning for new facilities or when expanding existing facilities that are already experiencing congestion problems. CAPACITY Highway Capacity Manual (HCM) 2000 ⚫ Standard for capacity analysis Definition by HCM 2000 The maximum hourly rate at which persons or vehicles can reasonably be expected to traverse a point or uniform section of a lane or roadway during a given time period under prevailing roadway, traffic, and control conditions LEVEL OF SERVICE Qualitative description of how a certain facility is performing Quality measure describing operational conditions within a traffic stream, generally in terms of such service measures as speed and travel time, freedom to maneuver, traffic interruptions, and comfort and convenience. Each LOS represents a range of operating condition and is defined by quantitative factors known as measures of effectiveness ⚫ LOS A (Excellent) ~ F (Heavy Congestion) LEVEL OF SERVICE Philippine Highway Planning Manual (PHPM) ⚫ Developed by the Planning Service of the DPWH provides a methodology to carry out the process of such analysis Defined based on the computed volume (hourly demand volume) and capacity ratio and the space mean speed of the traffic flow Philippine Highway Planning Manual -Volume -capacity ratio -space mean speed HCM Considers density as the main variable  LEVEL OF SERVICE FRSAUF Level Type Description Free flow Free flow, with low volumes and high speeds. A Drivers are virtually unaffected by the presence of others. Little or no restriction in maneuvering. Reasonably The level of comfort and convenience provided is B free flow somewhat less than at LOS A. Zone of stable flow with operating speeds beginning to be restricted somewhat by traffic conditions. Drivers will have reasonable freedom to select their speed but there is a decline in freedom to maneuver within the traffic stream from LOS A. LEVEL OF SERVICE Level Type Description Stable flow Still in zone of stable flow, but speed and C maneuverability are most closely controlled by higher volumes. Most of the drivers are restricted in the freedom to select their own speed, lane changing, or overtaking maneuvers. The level of comfort and convenience declines noticeably at this level. Approaching Approaches unstable flow. D unstable Speed and freedom to maneuver are severely flow restricted, and driver experiences a generally poor level of comfort and convenience. Small increases in traffic flow will generally cause operational problems.  LEVEL OF SERVICE Level Type Description Unstable flow Flow is unstable, and there may be stoppages of E momentary condition. Represents operating conditions at or near capacity level. All speeds are reduced to allow but relatively uniform value. Freedom to maneuver within the traffic stream is extremely restricted, and it is generally accomplished by forcing a vehicle to “give way” to accommodate such maneuver. Forced or Forced or breakdown flow. F breakdown The amount of traffic approaching a point exceeds the flow amount that can traverse the points. Queues form behind such locations. Operation within the queue is characterized by stop-and-go waves, and is extremely unstable. It is the point at which arrival flow causes the queue to form. VOLUME CAPACITY RATIO AND LOS Volume-Capacity Volume-Capacity Level Level Ratio Ratio A 0.00 – 0.60 A 0.00 – 0.20 B 0.61 – 0.70 B 0.21 – 0.50 C 0.71 – 0.80 C 0.51 – 0.70 D 0.81 – 0.90 D 0.71 – 0.85 E 0.91 – 0.99 E 0.86 – 1.00 F ≥ 1.00 F > 1.00 Source: Transportation Research Source: DPWH, 1982 Board (TRB), 2000 LEVEL OF SERVICE LEVEL OF SERVICE US HCM, the different measures of effectiveness that most appropriately describe the LOS for different types of facility Expressway segments Multilane highways Density Weaving areas Arterials Ave Travel Speed Type of Facility Measure of Effectiveness Basic expressway segments Density (passenger car/km/lane) Weaving areas Ave. Travel Speed (km/hr) Ramp junctions Flow Rate (car/hr) Multilane highways Density (passenger car/km/lane) Two-lane highways Percent Time Delay (%) Signalized intersection Ave. Individual Stopped Delay (sec/veh) Unsignalized intersections Reserve Capacity (car/hr) Arterials Ave. Travel Speed (km/hr) LEVEL OF SERVICE Basic Freeway Segment Level Density, pc/km/hr 7 4 A 0–7 5 6 B 7 – 11 C 11 – 16 D 16 – 22 E 22 – 28 F >28 INTERSECTION Intersection The points where traffic flow converges and where direction of travel changes Category: Shape Type of Structure Type of Operation Intersection Shape Refers to the configuration of the intersection and would depend largely on the number of legs 1. Three-Leg: T or Y 2. Four-Leg: Normal Crossing, Oblique, or Skewed/Staggered 3. Multi-Leg: Intersections with more than four legs 4. Rotary or Roundabout Intersection Type of Structure Either designed as at-grade intersection or grade separation such as flyover or interchanges Initially designed at-grade and are planned to be grade-separated in the future to cope with high traffic volume (easing congestion or reducing traffic accidents) Intersection Type of Operation Depend on the type of control or the rules and regulations Simplify traffic flow by reducing the number of conflicts of vehicles Operates as unchannelized or channelized, and unsignalized or signalized Intersection Type of Operation Channelization Simplified movements of vehicles as it leads drivers to one conflict at a time Signalization Greatly reduces crossing conflicts at the intersection area Basic Intersection Design Principle The maximum number of legs should be four. The number of conflicts increases exponentially as the number of intersection legs increases Staggered intersections should be avoided. Main traffic flow should be near straight as possible. Sharp turns, such as left and right turns, cause unnecessary reduction in traffic speeds Basic Intersection Design Principle Roads should not intersect at a small angle. Oblique intersections pose potential hazards and cause high severity of accidents due to the almost head-to-head collision of vehicles Minimum of 60° (optimum = 90°) Two intersections should be as far as possible from each other. Inadequate weaving section The distance between two intersections must be Distance = Design Speed X Number of Lanes X 2 Intersection Design Elements The primary purpose of an interchange is to provide change in the direction of travel. Configuration of turning geometries 1. Direct 2. Semidirect 3. Indirect Design Elements of an Intersection Approach 1. Left Turn Storage Bay 2. Through Lane/s 3. Exclusive Right Turn Lane 4. Corner Island 5. Turning Roadway 6. Median 7. Nose Treatment Methods of Control of Intersections Conflicts An event involving two or more moving vehicles approaching each other in a traffic flow situation in such a way that a traffic collision would ensue unless at least one of the vehicles performs an emergency maneuver  Three-Leg Methods of Control of Intersections Conflicts Often occurs at intersections The more the number of legs an intersection has, the more the number of conflicts it has Four-Leg Classification: 1. Merging 2. Diverging 3. Crossing 32 conflicts 8 conflicts Hierarchy of Intersection Control There are three basic levels of control that can be implemented at an intersection Level 1 – Basic rules of the road Level 2 – Direct assignment of right-of-way using YIELD or STOP signs Level 3 – Traffic Signalization Determination of which (and how many) conflicts a driver should be able to perceive and avoid through the exercise of judgment Traffic controls must be imposed to assist  Hierarchy of Intersection Control Two factors affect a driver’s ability to avoid conflicts: 1. A driver must be able to see a potentially conflicting vehicle or pedestrian in time to implement an avoidance maneuver - Involves considerations of sight distance and avoidance maneuver 2. The volume levels that exist must present reasonable opportunities for a safe maneuver to take place - Involves an assessment of demand intensity and the complexity of potential conflicts that exist at a given intersection  Methods of Control of Intersections Depending on the traffic volume using the intersection and the severity of conflicts 1. Unsignalized 2. Signalized 3. Grade Separation Methods of Control of Intersections Unsignalized Intersection No control at all Right-of-way Rule For minor road: When two vehicles arrive at the same time at the intersection, the vehicle on the right has the priority Yield or Stop Roundabout or Rotary Number of turning vehicles is almost equal to the number of through vehicles U-Turn Slot No clear control; not the major flow but sign states otherwise Methods of Control of Intersections Signalized Intersection Separation in time Conflicts between opposing or merging streams are prevented by giving the right of way to a given direction Maximum of 2 diverging conflicts per phase Grade Separation Eliminates the problematic crossing conflicts of the different movements of vehicles Flyover/overpass, underpass, or full-blown interchange Provide the safest and most efficient method of control but definitely the most costly, and sometimes unaesthetic Fundamentals of Signal Timing and Design Signal Timing and Design Involves several important components including the physical design and layout of the intersection Key elements 1. Development of a safe and effective phase plan and sequence 2. Determination of vehicular signal needs: Timing of “yellow” change and “all-red” clearance intervals for each signal phase Determination of the sum of critical lane volume (Vc) Determination of lost time per phase (tL) and per cycle length (L) Determination of an appropriate cycle length (C) ◻ Lost time: 2-phase = 6 sec; 4-phase = 12 sec Allocation of effective green time to the various phases defined on the phase plan ◻ Length: 60-80 sec Signal Timing and Design 3. Determination of pedestrian signal needs: Determine minimum pedestrian “green” time ≥ 15sec (15m) Check to see if vehicular greens meet minimum pedestrian needs If pedestrian needs are unmet by the vehicular signal timing, adjust timing or add pedestrian actuators to ensure pedestrian safety General Considerations in Signal Phasing Phasing can be used to minimize accident risks by separating competing movements Increasing number of phases increases the total lost time in the cycle All phase plans must be implemented in accordance with the standards and criteria, and must be accompanied by the necessary signs, markings, and signal hardware needed to identify appropriate lane usage The phase plan must be consistent with the intersection geometry, land-use assignments, volumes and speeds, and pedestrian crossing requirements Lost Time Phases increases, lost time increase Vary with the length of the yellow and all-red phases in the signal timing Start-up lost time, l1 = 2 sec / phase Motorist use of yellow and all-red, e = 2 sec / phase l1 = Y – e l1 = start-up lost time, sec/phase Y = y + ar l2 = clearance lost time, sec/phase tL = l1 + l2 tL = total lost time L = Σ tL y = length of yellow interval, sec ar = length of all red interval Y = total length of change and clearance intervals L = total lost time. s Cycle One complete indication of green yellow, and red. L = lost time Y = sum of y-values = critical volume/saturation flow ratio for lane group = va/s Allocation of Green Time After the cycle length is computed, the total green time has to be allocated to different movements or phases Capacity Given the amount of green time to an approach pr movement can be estimated S = saturation flow rate g = effective green C = cycle length Illustrative Problem Consider the traffic volumes and saturation flow rates for the different movements: Saturation Volume, Movement Approach Direction Flow Rate pcu/hr pcu/hr 1 North Through + Right 930 1800 2 South Through + Right 700 1800 3 East Through + Right 650 2000 4 West Through + Right 420 2000 Compute for the optimum cycle time. Use yellow = 3sec; all-red = 2sec; starting loss = 2sec LOS for Basic Freeway Segments Input Geometric Data Free-flow Speed (FFS) field measured, or Base Free-flow Speed (BFFS) Volume Base Free-flow Speed Volume Adjustment Adjustment Peak-hour Factor Lane Width If field Number of Lanes Number of Lanes measured Driver Population Interchange Density FFS is input Heavy Vehicles Lateral Clearance Compute free-flow speed Compute Flow Rate Define speed-flow curve Determine speed using speed-flow curve Compute density using flow rate and speed Determine LOS TRAFFIC CONTROL DEVICES Traffic Control Devices Manual on Uniform Traffic Control Devices (MUTCD) USDoT Federal Highway Administration to promote highway safety and efficiency by providing for the orderly movement of all road users on streets, highways, bikeways, and private roads open to public travel throughout the Nation notify road users of regulations and provide warning and guidance needed for the uniform and efficient operation of all elements of the traffic stream in a manner intended to minimize the occurrences of crashes Traffic control devices or their supports shall not bear any advertising message or any other message that is not related to traffic control.  Traffic Control Devices To provide for the safe and orderly movement of traffic To resolve conflicts between vehicles, vessels, or aircrafts To minimize the cost of transportation As traffic volumes increase, highway systems rely mostly on passive devices such as signs, marking, and traffic signals to supplement the rules of the road. Advantages of Traffic Control Signals Traffic signals that are properly designed, located, operated, and maintained will have one or more of the following advantages: A. They provide for the orderly movement of traffic. B. They increase the traffic-handling capacity of the intersection if: 1. Proper physical layouts and control measures are used, and 2. The signal operational parameters are reviewed and updated (if needed) on a regular basis to maximize the ability of the traffic control signal to satisfy current traffic demands. Advantages of Traffic Control Signals Traffic control signals that are properly designed, located, operated, and maintained will have one or more of the following advantages: C. They reduce the frequency and severity of certain types of crashes, especially right-angle collisions. D. They are coordinated to provide for continuous or nearly continuous movement of traffic at a definite speed along a given route under favorable conditions. E. They are used to interrupt heavy traffic at intervals to permit other traffic, vehicular or pedestrian, to cross. Disadvantages of Traffic Control Signals Traffic control signals, even when justified by traffic and roadway conditions, can be ill-designed, ineffectively placed, improperly operated, or poorly maintained. Improper or unjustified traffic control signals can result in one or more of the following disadvantages: A. Excessive delay, B. Excessive disobedience of the signal indications, C. Increased use of less adequate routes as road users attempt to avoid the traffic control signals, and D. Significant increases in the frequency of collisions (especially rear-end collisions).  Traffic Signals When properly used, traffic control signals are valuable devices for the control of vehicular and pedestrian traffic. They assign the right-of-way to the various traffic movements and thereby profoundly influence traffic flow. Traffic signals need to attract the attention of a variety of road users, including those who are older, those with impaired vision, as well as those who are fatigued or distracted, or who are not expecting to encounter a signal at a particular location. Traffic Signal Operates by assigning the right of way successively to intersection approaches Complex devices that can operate in a variety of different modes traffic control signals; pedestrian signals; hybrid beacons; emergency-vehicle signals; traffic control signals for one-lane, two-way facilities; traffic control signals for freeway entrance ramps; traffic control signals for movable bridges; toll plaza traffic signals; flashing beacons; lane-use control signals; and in-roadway lights.  Terms Indication The red, yellow, or green light that is displayed to drivers in a given movement Cycle The time required for one complete sequence of signal indications Interval The discrete portion of a cycle during which the movements with the ROW do not change A period of time during which no signal indication changes Phase (or Stage) The portion of the cycle during which the movements with the ROW do not change The time devoted to a particular movement Change Interval The yellow indication for a given movement The transition from green to red, in which movements about to lose green are given a yellow signal, while all other movements have a red signal To allow vehicle that cannot safely stop when the green is withdrawn to enter the intersection legally Clearance Interval The transition from green to red for a given set of movements During the interval, all movements have a red signal It is timed to allow a vehicle that legally enters the intersection on yellow to safely cross the intersection before conflicting flows are released  Green Interval The movements permitted have a green light, while all other movements have a red light Red Interval All movements not permitted have a red light, while those permitted to move have a green light Signal Phasing more phase more loss time more intersection delay Separation of time The right-of-way, yellow change, and red clearance intervals in a cycle that are assigned to an independent traffic movement or combination of movements The more the number of conflicts, the more the number of phasing needed. The number of phases employed at any intersection must be kept to a minimum, compatible with safety because with every phase added, there is a corresponding additional loss of green time, which leads to increased intersection delay. National Electrical Manufacturers Association (NEMA) Phase-Numbering Scheme Phase Diagram for Phase Sequence Traffic Signals Options for Left Turns Signal Operation Types of Signal Operation Pa Sa Fa c 1. Pretimed Operation 2. Semi-Actuated Operation 3. Full Actuated Operation 4. Computer Control Types of Signal Operation 1. Pretimed Operation Also known as Fixed-time Cycle length, phase sequence, and timing of each interval are constant Employ cycles and phases of predetermined length May employ different cycles at different times of day, they cannot respond to short-term demand fluctuations Typical to have at least an AM peak, PM peak, and an off-peak signal timing.  Types of Signal Operation 2. Semi-Actuated Used where the primary reason for signalization is interruption of continuous traffic Detectors are placed on the minor approaches to the intersection There are no detectors on the major street Loop Detector Types of Signal Operation 2. Semi-Actuated The indication is green for the major street at all times except when a “call” or actuation is noted on one of the minor approaches Types of Detector: 1. Impulse Detector 2. Presence Detector Types of Signal Operation 3. Full Actuated Every lane of every approach must be monitored by a detector Green time is allocated in accordance with information from detectors and programmed “rules” established in the controller for capturing and retaining the green Cycle length, sequence of phases, and green time split varies from cycle to cycle Types of Signal Operation 4. Computer Control The computer acts as a master controller, coordination the timings of a large number of signals It calculates an optimal coordination plan based on input from detectors places throughout the system Individual signals in a computer-controlled system generally operate in the pre-timed mode Coordinated Where randomness can no longer be ensured and there is a need for continuous movement over an arterial, coordination or synchronization of the timing of the signals in series is required. It is also possible that within an arterial, subgroups consisting of a number of intersections may be developed. Area Traffic Control Links + Nodes = Networks Optimization techniques have been developed to cope with such network SCATS – Sydney Coordinated Adaptive Traffic System SCOOT – Split Cycle Offset Optimization Techniques Data Requirements for Traffic Signal Setting In planning for phase pattern and determination of appropriate timing of signals 1. Traffic Volume All types of vehicles (incl. non-motorized) Directional 2. Pedestrian Flows Movement in all directions 3. Passenger Car Unit Values PCU equivalent of the different types of vehicles 4. Saturation Flow Rates Maximum flow rate occurring at the stop line once traffic initially in queue is given green time indication 5. Physical Characteristics of the Road Coordination of Traffic Signals To provide progressive movement of traffic flow that has to pass through a series of signalized intersections, some form of coordination has to be introduced to minimize delay Signal Coordination - timing of signals in relationship to one another so that vehicles traveling at a predetermined speed can pass through the greens of successive signals - also known as Signal Progression Coordination of Traffic Signals Simultaneous System All signals display the same color indication Commonly used when intersections are closely spaced ͯ Drivers tend to increase speed in order to pass as many intersections as possible Alternating System At any given instant of time, the driver sees intersections ahead with alternating green and red indications Intersections are far apart Progressive System Starts of green are arranged in such a way that traffic flow is uninterrupted and bandwidth is optimized One-way system or when one direction of flow Coordination of Traffic Signals Speed at which vehicles are presumed to travel through the coordinated signal system – Speed of Progression Space-time path intersecting the green at all signals – Through band The time difference between the beginning and end of the through band at any point – Band width The time difference between the beginnings of the green at any two signals – Offset