L1 Course Introduction - Recent Advances in Transportation and Traffic Engineering PDF

Recent Advance. In Transp. and Traffic Engineering Course Description This course consists of few modules that mostly address two major subjects: challenges and promising solutions of transportation. For instance, in one module we will talk about the challenge of traffic safety, a proble...

Recent Advance. In Transp. and Traffic Engineering Course Description This course consists of few modules that mostly address two major subjects: challenges and promising solutions of transportation. For instance, in one module we will talk about the challenge of traffic safety, a problem that cost Saudi Arabia 4 to 5 thousands lives annually. Another module focuses on the promising technology of connected and automated vehicles (CAVs). We will talk about the different types of this new technology as well as its impact on safety, mobility and emissions. The course include other trending topics in transportation including electric cars and intelligent transport systems (ITS). Course topics include: Transport safety. Transport congestion and emission. Autonomous vehicles and their sensors. Intelligent Transportation Systems (ITS) and their application. Course Learning Outcomes K1: Identify components, advantages, and disadvantages of some recent transport technologies such as autonomous vehicles, and Intelligent Transportation Systems (ITS). V1: Compare the impact of different transportation modes on safety, society, and the environment. Run traffic simulation. Course Assessment Percentage of Total Assessment Assessment Activities * Score Project & Assignments 15 % Quiz 20 % Midterm 25 % Final 40 % Perfect attendance +3% Course Plan  Week Date Module Lecture Task 1 18-8 to 22-8 L1_course_intro 2 25-8 to 29-8 L2_road_safety_intro Class Activity 1 Safety 3 1-9 to 5-9 L3_road_safety_in_ksa HW1 Course Plan 4 8-9 to 12-9 L4_safe_system_approach Class Activity 2 Mobility & Emissions 5 15-9 to 19-9 L5_congestion Quiz 1 L6_shockwaves HW2 6 29-9 to 3-10 L7_road_emissions Quiz 2 7 6-10 to 10-10 Midterm Midterm  Week Date Module Lecture Task 8 13-10 to 17-10 L8_HVs HW 3 9 20-10 to 24-10 L9_AVs Class Activity 3 CAVs 10 27-10 to 31-10 L10_CAVs Class Activity 4 11 3-11 to 7-11 L11_EVs HW 4 12 17-11 to 21-11 L12_ITS_intoduction Quiz 4 Course Plan 13 24-11 to 28-11 L13_ATIS Class Activity 5 ITS 14 1-12 to 5-12 L14_TIM HW 5 15 8-12 to 12-12 L15_APTS Quiz 5 16 15-12 to 19-12 17 22-12 to 26-12 Finals Finals 18 29-12 to 2-1 End of 1st semester Lecture 1: Introduction to Recent Advance. In Transp. and Traffic Learning Objectives: Explain transportation and identify its purpose. Identify types of transportation. Identify costs of transportation.  Transportation Definition Transportation is moving people and goods from one place to another to increase the accessibility of activity and resources by overcoming distance. The word ‘transportation’ comes from the Latin words Trans(across) and portable (to carry). To carry across! See (1, 2, 8, 12) at the end of the section.  Transportation is ‘mean’ not a ‘goal’ “Mobility is perhaps the single greatest global force in the quest for equality of opportunity (Martin Wachs, 2011)”. We travel everyday to do certain goals using transportation. Doctors use transportation to go to hospitals for the goal of saving people lives, supermarkets use transportation for the goal of delivering their products, etc. Transportation is mean (not a goal) that enables other goals by providing access. See (1, 2, 8, 12) at the end of the section.  Types of Transportation Transportation is often divided based on infrastructure: Highway Rail Water Air Pipeline Cars Buses Trucks See (1) at the end of the section.  There is No Perfect Mode Personal cars Airplanes + Reliable/comfortable/flexible + Fast - Expensive to buy/ emission/ safety - Expensive/ emission Modes Truck shipping Waterway shipping + Fast/door-to-door delivery + cheap - Can be expensive/ emission/ safety - slow See (8) at the end of the section. Selecting Transportation Modes Example (on mode selection): An individual wants to travel between two cities (city A and city B). The distance between the two cities is 400 miles. There are three travel options available: Hint: this trip is a business trip where time is important. The company is willing to pay $25 per 1 hour saved. Mode Trip involves.. Air (1) driving to the airport in city A, (2) parking, waiting at the terminal, (3) flying to the airport in city B, (4) walking to a taxi stand, and taking a taxi to the final destination. Auto (1) driving 400 miles through several congested areas, (2) parking in the downtown area, and (3) walking to the final destination. Rail (1) taking a taxi to the railroad station in city A, (2) traveling directly to downtown city B, and (3) a short walk to the final destination. See (8) at the end of the section. Selecting Transportation Modes Question: Which mode would you select based on time and cost? Hint: this trip is a business trip where time is important. The company is willing to pay $25 per 1 hour saved. Direct costs for each mode are as follows: Air cost $250 with a total travel time of 5 hours (highest cost and lowest time). Auto (vehicle) cost $200 with a total travel time of 8 hours (medium cost and time). Rail cost $150 with a total travel time of 12 hours (lowest cost and longest time). See (8) at the end of the section. Selecting Transportation Modes Solution Mode Time Cost (including time cost) Air 5 hours $250 + $25(5) = $375 Auto 8 hours $200 + $25(8) = $400 Rail 12 hours $150+ $25(12) = $450 What other factors might be considered by travelers? Safety: travelers may feel safer in one mode than another. Rail might be considered safer by some travelers compared to driving or flying. Reliability: Attending a job interview might push travelers to use one mode over another. Convenience/comfort: Flexibility and comfort of the ride might attract travelers to (e.g., personal cars compared to public transit). See (8) at the end of the section. Good Transportation Is … Transportation Engineering is defined (by the Institute of Transportation Safe Efficient Engineering) as: ‘The application of technology and scientific principles to the planning, Fast Comfortable functional, design, operation and management of facilities for any mode of transportation in order to provide for the Convenient Economical safe, efficient, rapid, comfortable, convenient, economical, and environmentally compatible movement of Environmental people and goods. ’ See (8) at the end of the section. Transportation Costs (bad impact) People’s time Air pollution. and effort. Noise Congestion Land- Road crashes use/Energy See (1) and (2) at the end of the section.  Transportation Costs (Land-use) Transportation systems require huge resources including energy, People’s time and Air pollution. material, and land. effort. Up to 50% of land is consumed by transportation in some major cities (e.g., parking spaces, roads, and Noise Congestion other infrastructures). Road crashes Land-use/Energy See (8) at the end of the section.  Transportation Costs (Env. Impact) Environment: Noise, environmental impact, and People’s time and Air pollution. effort. energy inefficiency are among the externalities of transportation. Noise Congestion Road crashes Land-use/Energy See (8) at the end of the section.  Transportation Costs (Env. Impact) Constructing infrastructures such as roads, airports, parking lots, etc. People’s time and effort. Air pollution. Energy and emissions required for the movement of people and goods. Production and disposal of Noise Congestion transportation products such as vehicles and airplanes. Road crashes Land-use/Energy See (2) at the end of the section.  Transportation Costs (Env. Impact) A huge amount of energy is required to overcome space in a global economy. Some of the biggest consumers of energy include vehicles and terminal equipment. 74% of transport emissions come from road transport (passenger cars and trucks). See (2, 9 and 10) at the end of the section.  Transportation Costs (Env. Impact) The Environmental Problems of Transportation include: Non-environmental City Planning: car-dependent cities where people and services are far from each other produce People’s time more emissions than compact cities where cycling, and effort. Air pollution. walking, and use of public transport are common. Non-environmental Mode: Increasing emissions through tailpipe emissions such as driving combustion-engine Noise Congestion vehicles (a cleaner option would be electric trains). Non-environmental Industrial Production: Increasing emissions by producing fuel, vehicles, or construction Land- material. Road crashes use/Energy See (2) at the end of the section.  Transportation Costs (Safety) Safety: All modes bring some risks to users People’s time and Air pollution. effort. with road transport being the worst in terms of safety. Noise Congestion Road crashes Land-use/Energy See (8) at the end of the section. Transportation Costs (Safety) Every year 1.35 million people die on the world’s roads, including more than People’s time and Air pollution. 182,000 children. effort. Majority of these deaths and injuries are preventable. Noise Congestion Road crashes are the number one killer of 5 to 29-year-olds. Road crashes are the 8th leading Road crashes Land-use/Energy cause of death globally (UNECE data). See (3) at the end of the section.  Transportation Costs (Safety) Should we call a vehicle crash an accident? If traffic crashes are indeed accidents, then how can they be studied scientifically, and how can science improve traffic safety? Crashes are often preventable and therefore should not be called ‘accidents’. The U.S. National Highway Traffic Safety Administration (NHTSA) replaced the term “accident” with the term “crash” in all their official documents and communications in 1996 (NHTSA, 1996). ‘ Accident’ is more loaded than a crash and implies a chance event, one that is out of the driver’s control. If a crash is a chance event, then by implication it cannot be foreseen, and therefore cannot be prevented. See (4) at the end of the section. Transportation Costs (Safety) Old New Goal Make driving safer. Make the whole transportation system safer. Risk Occupant risks, measured by Total risks, including risks to occupants and measurement distance (e.g., occupant deaths per other road users, measured by distance and 100,000 million vehicle-miles). per capita. Solutions ▪ Roadway and vehicle design ▪ Walking, bicycling and public transit considered improvements. improvements. ▪ Graduated licenses and senior ▪ Road, parking, fuel and insurance pricing driver testing. reforms. ▪ Seatbelt and helmet ▪ More connected and complete streets. requirements. ▪ Smart Growth development policies. ▪ Anti-impaired and distracted ▪ Transportation demand management driving campaigns. programs. ▪ Traffic speed reductions. Analysis scope Cost + safety benefits Economic + social + environmental See (5) at the end of the section. Inverting Transportation System image See (11) at the end of the section.  Transportation Costs (Congestion) Transportation facilities (e.g., walkways, stairways, roads, busways, People’s time and Air pollution. effort. railways, etc.) are considered congested when demand for their use exceeds their capacity. Noise Congestion Road crashes Land-use/Energy See (6) at the end of the section.  Transportation Costs (Congestion) Congestion happens when the volume-to-capacity ratio exceeds 1 (i.e., the facility is used above design capacity). image See (7) at the end of the section.  What is your role as a transportation engineer? To balance the need of society for fast and People’s time efficient transportation with the cost Air pollution. and effort. involved. So, transportation engineers should provide ethical solutions that are mobile as well as safe, and environmentally Noise Congestion responsible. Road Land- crashes use/Energy See (8) at the end of the section. Resources 1. David Levinson et al. https://eng.libretexts.org/Bookshelves/Civil_Engineering/Fundamentals_of_Transportation 2. 4.1 – Transportation and Energy | The Geography of Transport Systems (transportgeography.org) 3. https://unece.org/DAM/trans/roadsafe/publications/Road_Safety_for_All.pdf 4. Shinar, 2017 - https://doi.org/10.1108/978-1-78635-221-720162029 5. A New Traffic Safety Paradigm 6 November 2023 Todd Litman Victoria Transport Policy Institute. https://www.vtpi.org/ntsp.pdf 6. The Geography of Transport Systems: https://transportgeography.org/contents/methods/transport-technical- economic-performance-indicators/levels-of-service-road-transportation/ 7. Falcocchio, J. C., & Levinson, H. S. (2015). Springer Tracts on Transportation and Traffic Road Traffic Congestion : A Concise Guide. https://link.springer.com/book/10.1007/978-3-319-15165-6 8. ‫هندسة المواصالت – الكورس الثاني‬https://www.youtube.com/playlist?list=PLgWZcxtKR7JPCpr8ynQ1jhjRqLAwmqyOX 9. International Energy Association. IEA and IPCC (2014) Summary for Policymakers. 10. The Geography of Transport Systems: https://transportgeography.org/contents/chapter4/transportation-and- environment/greenhouse-gas-emissions-transportation/ 11. Strategy& https://www.strategyand.pwc.com/m1/en/reports/2021/sustainable-mobility.html 12. Bazzan, Ana & Klügl, Franziska. (2013). Introduction to Intelligent Systems in Traffic and Transportation. Synthesis Lectures on Artificial Intelligence and Machine Learning. 7. 1-137. 10.2200/S00553ED1V01Y201312AIM025. Lecture 2: Introduction to Road Safety Learning Objectives: 1. Define and measure road safety. 2. Identify most affected road users. 3. Explain challenges for improving road safety.  Introduction to Road Safety Define and measure road Identify most affected Explain challenges for safety. road users. improving road safety. World’s First Road Fatality First Person to Die Due to Road Accident: Irish amateur scientist, Mary Ward, died in 1869 due to a road accident. She fell out of her cousin's steam car, breaking her neck. The vehicle speed was estimated to be 3.5 to 4 miles per hour. When: 31st of January 1869. Where: Ireland Who: Mary Ward. World’s First Autonomous Vehicle’s Fatal Crash First Fatality Involving First Fatality Involving Autonomous Vehicle Autonomous Vehicle First Fatality Involving Autonomous Vehicle A backup (safety) driver of self-driving Uber crash pled guilty to one count of endangerment. She was behind the wheel during the crash and was sentenced to three years' probation. This is believed to be the first fatal collision involving a self-driving car. When: On March 18th, 2018 Who: Rafaela Vasquez Where: Arizona, U.S. images Part 1: Define and measure road safety.  What is the goal of road safety? A traffic collision is the incident of a motorized vehicle (motorcycle, car or truck, etc.) hits and other object. Can we call cyclist hits a pedestrian a traffic collision? What do we mean by ‘safe’ transport system? A safe transport system that is absence of risk or danger that enables a person to travel freely without injury or death.  What is the goal of road safety? Minimize (not eliminate) crashes and the consequent fatalities and injuries, it is essential to utilize all available tools, knowledge, and technology. 3 conditions to count an incident as a road collision or road crash: 1.Happen on a public highway or road involving at least one motorized vehicle. 2.Causes damage, injuries, or fatalities to any involved parties. 3.Includes car crashes as well as incidents involving cyclists, pedestrians, and other road users. Important Road Safety Terminologies: Fatal accident: Any injury accident resulting in a person killed. Non-fatal accident: Any injury accident other than a fatal accident. Casualty: Any person killed or injured as a result of a road accident. Road accident death: Any person killed immediately or dying within 30 days as a result of a road accident, excluding suicides. How to measure and compare road safety? How to measure and compare road safety? Why All Countries Should Use the Same Metrics for Measuring Road Safety: This will allow for comparison and accurate measure of performance. Accurate measure of performance can enable countries to address the problem and measure the effectiveness of their solutions. Road safety is measure by crash outcome (severity) or type of injuries sustained to the people involved in the crash (typically categorized by fatalities and injury severity). How to measure and compare road safety? Metrics used for Measuring Road Safety: Crash frequency: The number of crashes occurring per year or other unit of time (fatality/year or injury/year). Crash rate: The number of crashes normalized by a particular population or metric of exposure (fatality/100,000 or injury/100,000). Crash Number per Distance Travelled: The crash numbers per miles traveled or licensed drivers (fatality/mile or fatality/kilometer or injury/mile). Crash Number per number of vehicles: The number of fatalities per million passenger vehicles (fatality/million passenger vehicle or injury/million passenger vehicle). Note: severity of those crashes should always be taken in consideration. Crash rate for different parts of the world (2016) Part 2: Identify most affected road users. Fact 1: Road Crashes 1st Cause of Death for Young People (aged 5-29 years) Source: WHO, 2019 Fact 2: Low-income have higher % of deaths compared to higher-income countries (WHO, 2021).  Fact 2: Low-income have higher % of deaths compared to higher-income countries (WHO, 2021). Low-income countries: With 21 deaths per 100,000 people, low-income countries have the highest mortality rates. High-income countries have the lowest, at eight deaths per 100,000 people. Socioeconomic status: Over 90% of road traffic deaths occur in low- and middle- income countries, with highest rates in the African Region and lowest in the European Region (source). Fact 2: Low-income have higher death rates higher- income countries (WHO, 2021). Low-income countries: With 21 deaths per 100,000 people, low-income countries have the highest mortality rates. High-income countries have the lowest, at eight deaths per 100,000 people. Socioeconomic status: Over 90% of road traffic deaths occur in low- and middle-income countries, with highest rates in the African Region and lowest in the European Region (source). Fact 3: There is a decrease in global death rate over last 10 years especially in 2019 (WHO, 2021). Fact 3: There is a decrease in death rate over last 10 years especially in 2019 (WHO, 2021). COVID-19 Impact on Traffic Safety: Global traffic volumes fell in March 2020. Europe experienced significant traffic drop in April. 17 consistent countries saw 13% decrease in traffic volume, 16% reduction in road deaths. Fact 4: Low % of +3 stars rating roads (WHO, 2021). Fact 5: 50 km/h speed is urban areas is not enforced in many countries (WHO, 2021). Fact 6: Less Driving Equal Less Deaths  Fact 6: Less Driving Equal Less Deaths Data shows that: More driving leads to more fatalities (Litman, 2024). Also, when public transit travel increases, the fatality rate decreases. Therefore, encouraging public transit (trains and buses) will make cities safer compared to driving (see figure below). Also, from an environmental perspective, traveling by train or a bus produces fewer emissions compared to private cars.  Fact 6: Less Driving Equal Less Deaths Data shows that: More driving leads to more fatalities (Litman, 2024). Also, when public transit travel increases, the fatality rate decreases.  Fact 6: Less Driving Equal Less Deaths Data shows that: Vehicles produce higher fatalities than other modes. More driving results in more fatalities. Mode: Over 25% of road traffic deaths and injuries in 2018 were pedestrians and cyclists (source). Serious crashes rose in tandem with the number of vehicles. Public transit is way safer than driving. Fact 7: More male die than female Men die three times more than women in road crashes. Men primarily die as car drivers and motorcycle riders. Women are killed as pedestrians and car passengers. Fact 7: More male die than female Why More Males Die Because of Road Crashes than Females? Earlier involvement with driving. Higher driving speed. Risky driving behavior. Less regard for traffic laws.  Example of world’s effort to address death rate of road crashes UN Decade of Action for Road Safety 2021-2030 aims to halve global road crash deaths and injuries by 2030. The plan provides a blueprint for national and local road safety plans and targets. Part 4: Explain challenges for improving road safety. Why improving road safety can be complicated? Improving safety is a crucial aspect of the transportation system. Safety Other transportation objectives include mobility, efficient movement, environmental concerns, public health, and economic growth. The challenge is finding the balance between these goals and limit their conflict. Mobility For instance, improving safety can reduce mobility or other transport goals.  Example of conflicting goals (safety vs. mobility): Roundabouts: A city may install a roundabout at an intersection to reduce conflicts and improve safety, particularly for left turns. However, this requires slower traffic on the main road, potentially decreasing throughput during heavy traffic. Example of conflicting goals (safety vs. mobility): Traffic Signal Installation: High-speed, high-volume road separates housing developments from elementary school. Traffic signal and crosswalk installation will increase safety. However, it a traffic signal will also increase delays for motorists due to student crossing. Example of conflicting goals (safety vs. public comfort): Red Light Cameras: Red light cameras monitor intersections, record violations, and cite violators, improving safety and reducing serious injury crashes. However, Red Light Cameras can also increase public opposition due to hefty fines. image  Example of conflicting goals (motorists vs. cyclists): Rumble Strips: In rural locations, rumble strips can be installed alert drivers and increase their safety. However, these rumble strips can take the space of cyclists' lanes and make cycling difficult and unsafe. image Lecture 3: Road Safety in Saudi Arabia Learning Objectives: Identify the status of road safety in Saudi Arabia compared to the world. Identifying causes of crashes in Saudi roads. Identifying characteristics of crashes in Saudi Arabia. Lecture 3: Road Safety in Saudi Arabia Part 3: Part 1: Characterist Part 5: Status of ics of Recommen Road Safety crashes in dations. in KSA KSA. Part 2: Causes of Part 4: Cost road of crashes in crashes in KSA. KSA. Growth in population, wealth and transportation demand Population: Saudi Arabia's population has grown six times in the last four decades, reaching 31.7 million in 2017. Foreigner: Expats make up about 37% of the population (third). Oil boom led to economic growth and improved living standards. Growth in population, wealth and transportation demand Asphalted road network length has increased from 239 km in 1952 to 64,632 km. Motor vehicle numbers have also increased from 145,000 in 1970 to 18 million today, with 800,000 imported annually.  Agencies involved in road safety General Directorate of Traffic. Ministerial Ministry of Committee for Transportation. Traffic Safety. Ministry of Municipalities. Health. Saudi Red Crescent Society. Regulations to improve road safety in KSA Established in 1960 for traffic Motor vehicle periodic regulations, surveillance, inspection program (MVPI) driver education, vehicle since 1985. testing, and collision reporting. Obligation for third-party Establishment of Ministerial insurance and seatbelt use in Committee of Traffic Safety in 2002. KSA Part 1: Status of Road safety in KSA. Road crash statistics in KSA In 2019, 287,781 road crashes resulted in 5,754 deaths and 32,910 injuries. Estimated annual GDP loss due to road crashes is 2.2% to 4.7%. Over one million deaths and injuries in road crashes occurred from 1970- 2008, affecting 4% of the KSA population. Intervention measures using education, engineering, and enforcement can minimize losses. Crash Statistics of Ministerial Committee of Traffic Safety Road safety in KSA compared to other countries See notes below for data source Part 2: Causes of road crashes in KSA. Causes of road crashes in KSA Speeding: 35.69%. Improper turning: 8.43%. Improper passing: 8.01%. Traffic signal violations: 7.88%. Improper stopping: 7.81%. Other behaviors: 32.17%. Note: all of the above are user behavior (e.g., we do not see road design or vehicle problems). Causes of road crashes in KSA 80 to 90% of road crashes attributed to road user behavior such as: 1. Risky driving behaviors (e.g., speeding or tailgating). 2. Mobile phone use. 3. Not wearing seatbelt. 1. Risky driving behavior: a. Gender. 1. Risky driving behavior: b. Expat drivers. Expat drivers, due to dependency on motor vehicles and lack of reliable public transport, contribute to 40% of road crashes in KSA. Drivers from countries with high collision rates and aggressive driving behaviors are more likely to engage in risky driving. 1. Risky driving behavior: c. Age. Age is a major factor as the median age of the Saudi population is 26.7 years, suggesting a younger demographic is more likely to engage in risky driving. Teenagers are more susceptible to ignoring traffic signals, with over 2,000 teenage drivers caught running red lights in one year. 2. Mobile phone use while driving: Saudi Arabia has 176.6 mobile- cellular subscriptions per 100 inhabitants, a high rate globally. Mobile phone use while driving is a significant contributor to road crashes. Studies show 85% of high school and university students use their phones while driving (general statistics). Making or receiving phone calls while driving increases the risk of traffic crashes seven times. 3. Seatbelt wearing rates and crash severity: Non-use of seat belts increases severity of MVCs. Seat belts reduce injury risk in crashes, with head, neck, cervical, and spine regions most affected. Seat belts became compulsory in Saudi Arabia on December 5, 2000, reducing the wearing rate from 2% to 3%. Children under six years of age are at higher risk during vehicle collisions. Fatalities and injuries decreased by about 20% and 10% respectively in the first year after the seat belt law. Initial public awareness campaigns and strict enforcement by traffic police followed the law. 3. Seatbelt wearing rates and crash severity: Bendak's study showed a significant increase in seat belt wearing rates from 2% to over 60% for drivers and from 0% to 23% for front-seat passengers. This led to a decrease in head, spinal, pelvis, and bleeding injuries due to road crashes. A follow-up study found a drop in wearing rates to 28% for drivers and 15% for front-seat passengers due to less stringent law enforcement. Self-reported seat belt wearing rates did not match observed rates, resulting in lower actual wearing rates. Al-Turky et al. reported a mismatch between drivers' beliefs and actual usage as 88% believe in seat-belts and less than 3% actually wear them, the study said. Part 3: Characteristics of crashes in KSA. Characteristics of crashes in KSA: 1. Types of collisions Frontal and side collisions are the most common types of vehicle collisions leading to deaths or injuries. Other types include rear-end collisions and rollovers. Head, thorax, arms, and spine are the most injured parts due to car crashes. 52% of victims died at the crash scene, 5% died during transport, and 43% died after hospital admission. Characteristics of crashes in KSA 2. Vulnerable road users: Over 25% of severe road crashes in KSA involve pedestrians, causing significant human and financial costs. Al-Ghamdi's study evaluation of 638 pedestrian-vehicle crash cases in Riyadh found 80% of severely injured pedestrians experienced multiple injuries, 50% had head, spine, and trunk injuries. The study found that 42% of pedestrian victims were aged 15 years or younger, making them most vulnerable to pedestrian crashes.  Characteristics of crashes in KSA 3. Vehicle animal collisions: Large animal collisions typically result in higher frequency of injuries to the victim's head, neck, and upper torso area. Over 700,000 camels graze freely in KSA, with over 600 camel-vehicle collisions occurring annually. MoT has implemented infrastructural measures to prevent these collisions, including highway fencings and overpasses for camels. Despite a significant drop in collisions, the number of such collisions continues to rise. More aggressive mitigation measures are needed to prevent camel-vehicle collisions. image Part 4: Cost of road crashes in KSA. Cost of crashes in KSA 1. Death rate Data collected from different agencies might be different. For instance, Barrimah et al.'s study shows higher death rates due to traffic crashes in MoH records than police-reported ones. Road crashes cause up to 4.7% of all mortalities in Saudi Arabia, compared to less than 1.7% in developed countries.  Cost of crashes in KSA 2. Annual cost. ADA's study found road crashes in KSA cost approximately US$ 6.73 billion annually. image Cost of crashes in KSA 3. Common Crash injuries in KSA Cost of crashes in KSA 4. Long-term injuries and overwhelming hospitals: Hospital stays average 10 to 13 days. MVCs were the direct cause of 73.6% of all hemiplegia, paraplegia, and tetraplegia cases in KSA. it was reported that head (22-35%) and spine (5-9%) were the most common fatal injuries among road crash victims, both of which usually require long stays in hospitals [71, 82, 84]. These figures strain the medical system and deprive the country of vital medical resources. Part 5: Recommendations to address road crashes in KSA.  Urgent need for change in road user safety behavior to minimize risk of Multi- Visible Collisions (MVCs). Enhancing road user awareness, introducing stringent traffic regulations, tougher penalties, and engineering solutions are necessary. Recommendations Need to develop and introduce new safety measures appropriate for Saudi Arabia's situation. Enhancement of public transport system by introducing alternatives to private vehicles like trains and buses. Recommendations Enhancement of driver licensing process to convey importance of safe behaviors to younger drivers. Provision of sustained educational programs on safety issues and proper driving behaviors, especially targeting young drivers. Mandatory road safety messages on all television and radio channels in Saudi Arabia. Urgent need to establish a centralized road crash database for aiding in road safety policies, regulations, and technological changes. For more Bendak, S., Al-Shammari, N., & Kim, I. info read the (2022). Fifty years of motor vehicle crashes in Saudi Arabia: a way forward. ˜the œ Open Transportation Journal, 16(1). following https://doi.org/10.2174/18744478-v16- e2208180 report Lecture 4: Safe System Approach Learning Objectives: Identifying cutting edge solutions for road safety: Safe System Approach. Explain effects of speed on crash severity. Identify types of collisions during car crash.  Safe System Approach Part 4: Part 6: 7 Part 5: Part 1: Safe Part 3: Types of advantages Part 2: Safe Vehicle System Crash collisions of lower Speed. safety Approach. severity during road speed features. crash. limit. Part 1: Safe system approach. What is the Safe system approach? Data-driven, holistic approach. Integrates user needs. Predicts errors. Forgiven system that minimize crash impact on road users. Has 5 interdependent elements that work together to enhance road safety. 5 Elements of safe system approach Elements of safe system approach are interdependence Safe System Approach's elements affect each other (e.g., roads influence speed). For instance, people drive faster on highways with wider lanes. Therefore, drivers' behavior is influenced by the infrastructure available. This shows the interdependence of road safety approach elements. So, to have safe roads we need to address all 5 elements of the Safe Road Approach. Safe Speed: Driving speed is a key factor in road safety because: High speed narrows driver field vision. High speed reduce reaction time available and increase needed stopping distance for drivers. High speed increases the kinetic energy transferred during a collision, resulting in more severe injuries. Design speed VS. Operating Speed VS. Speed limit Design Speed: "A selected speed used to determine the various geometric design features of the roadway, such as horizontal alignment, vertical alignment, and cross-section design elements," (AASHTO 2018). Operating Speed: The speed at which a driver operates a typical vehicle or the speed at which all traffic moves in a free-flow situation. Operating Speed is the speed at which most people drive, whether or not it is safe to do so. Speed limit: The Manual on Uniform Traffic Control Devices (MUTCD) defines the speed limit as "the maximum (or minimum) speed applicable to a section of highway as established by law or regulation“. Part 2: Explain effects of speed on crash severity. (1) Kinetic energy Kinetic energy is the energy gained by moving in a car. This energy has to be transferred somewhere. Kinetic energy will transfer to thermal energy using the brakes to stop a car safely. In a crash, modern cars absorb energy by deforming the car's structure. In higher-speed crashes, kinetic energy transfers to drivers and passengers resulting in injuries or deaths. Less speed and less mass produce less kinetic energy and therefore less crash image severity. (2) Impulse Impulse quantifies force's impact on an object over time. Crash severity is higher if the vehicle stopped quickly and if resistive force is higher. “Speed has never killed anyone. Suddenly becoming stationary (impulse), that's what gets you (Jeremy ClarksonVehicle).“ Safety design focuses on increasing crash duration to reduce injury severity. Seatbelts, airbags, padded helmets/jackets, and roadside barriers increase crash duration.  (2) Impulse Crash Without an Airbag A 60 kg60 kg crash test dummy is traveling in a car moving at 30 m/s30 m/s. The car collides with a wall and comes to rest. Without an airbag, the crash test dummy hits the steering wheel and comes to rest in 0.05 s0.05 s. How much force does the dummy experience in the collision? Solution First, we will calculate the change in momentum : Δp = mΔv Δp=(60 kg)(0 m/s−30 m/s) Δp=−1,800 kg⋅m/s Now applying the impulse-momentum theorem: J= F⋅t =Δp F(0.05 s)=(−1,800 kg⋅m/s) Dividing by time produces: F= (−1,800 kg⋅m/s) / (0.05 s) F=−36,000 NF=−36,000 N This massive amount of force would almost certainly cause serious and potentially deadly injuries to a real passenger.  (2) Impulse Solution Crash With an Airbag Now the same crash test is conducted but with an airbag that brings the crash test dummy to rest in 0.3 s. With the airbag, how much force does the dummy experience? Here, the change in momentum is the same but the time is greater. We will apply the same method as before to calculate the force, but substitute the longer time of 0.3 s: F= (−1,800 kg⋅m/s) / 0.3 s F=−6,000 N While that increase in time would be almost imperceptible to the human eye, the result is a significant reduction in the collision force. So, collisions that take longer time result in less harm to drivers.  Inertia is an object's property to remain at rest or in motion until a sufficient external force is applied. (Newton’s First Law of Motion). (3) Inertia In a vehicle, any occupant experiences the same inertia as the vehicle. Restrained occupants experience the same sudden change in motion as the vehicle. Unrestrained occupants are in danger because they continue to move with the vehicle's initial inertia. Image Example of inertia during car crash Source: Crash Test - Belted vs Unbelted Passengers Can the human body sustain vehicle crashes? Source: Meet Graham: He's Designed To Survive A Car Crash And Teach A Lesson  Part 4: Identify types of collisions during car crash. Three Collisions Happen During a Car Crash: (1) Vehicle-Object Collision: Vehicle-object collision is the first stage of car crash where initial collision occurs between a vehicle and an external object. Factors like the angle, and speed of the crash influence the outcome and degree of injury. If a vehicle hits a large, static object, the force is thrust back onto the vehicle in rapid motion, causing the car body to crumple and bend. If a vehicle hits another moving object, factors like vehicle size, mass, and speed also play. If two identical cars are traveling at the same speed and in opposite directions, the force applied to each other will be the same, resulting in equal impact. image  (2) Vehicle-Occupant Collision: Vehicle-occupant collision is the second stage collision where the people in the car and car parts collide due to kinetic energy and Newton's 1st Law of Motion (inertia). Forces preventing movement include seatbelts, airbags, steering wheels, dashboards, or windshields. Injuries can include collar bone fractures, broken ribs, and pneumothorax (collapsed lung). image  (2) Vehicle-Occupant Collision: Seatbelt serves as the first line of defense in a frontal crashes. It supports the body and prevents contact with the steering wheel. The seatbelt holds the body by the chest and pelvis, transferring energy to these strong body parts. Incorrect seatbelt placement can result in organ damage, especially for shorter or taller individuals. Even a broken collar bone after a crash indicates the seatbelt's effectiveness. image (3) Human's Organ Collision: Softer organs may bruise or tear, while the heart or brain can rupture or stop functioning. Preventive measures like seatbelts, correct chair positioning, and staying under the speed limit can significantly impact injuries. The energy in a crash is proportional to the square of the speed. Increased speed by 10% increases energy and injury extent by 20%. image Part 5: Vehicle safety features. How to reduce crash severity? Reduce kinetic energy transferred to occupants by reducing speed and mass. Delay time to stop during a crash (impulse). Next, we will see how vehicle design reduces crash severity.  Safety Features in Vehicles: Vehicle engineering addresses the laws of physics in crashes, including Inertia, Impulse, Conservation of Energy, and Momentum. If unbelted, the body moves forward at the car's speed before the crash until it contacts the steering wheel with the chest and head on the windscreen. The body's response to energy is better when given enough time to absorb it. Vehicle design focuses on reducing speed and increasing time to stop (longer time to stop less force and safer crash). image  Safety Features in Vehicles: Seat belts and crumple zones in cars help protect occupants during crashes, preventing kinetic energy transfer and increasing accident duration (impulse). Airbags provide additional cushioning, but not the same safety without seat belts. Helmets absorb the kinetic energy of impact, reducing skull force. Cycling helmets use MIPS technology to handle rotational impact forces. Child car seats have special designs to protect children, as seat belts are ineffective for children. photo Impact of seatbelts and airbag on impulse (safety) A car traveling at 27 m/s collides with a building. The collision with the building causes the car to come to a stop in approximately 1 second. The driver, who weighs 860 N, is protected by a combination of a variable- tension seatbelt and an airbag ((Figure)). (In effect, the driver collides with the seatbelt and airbag and not with the building.) The airbag and seatbelt slow his velocity, such that he comes to a stop in approximately 2.5 s. A. What average force does the driver experience during the collision? B. Without the seatbelt and airbag, his collision time (with the steering wheel) would have been approximately 0.20 s. What force would he experience in this case? Impact of seatbelts and airbag on impulse (safety) A. What average force does the driver experience during the collision? Solution Impulse when time to stop is 2.5 seconds: Impulse (J) force multiplied by time : 𝐽 = 𝑚 ∆𝑣 = 𝐹 ∆𝑡 860 𝑁 𝑚= = = 87.8 kg 9.8 𝑚ൗ𝑠2 𝑚 ∆𝑣 87.8 (0−27) 𝐹= = = −948 𝑁 ∆𝑡 2.5 Impact of seatbelts and airbag on impulse (safety)  Safety Ratings NCAP stands for New Car Assessment Program, and it’s a system used to evaluate vehicle safety performance. Even between cars, smaller cars face the brunt of impact, regardless of their NCAP rating. NCAP ratings are compared between vehicles of similar mass, not against all vehicles. A 5-star rated hatchback performs well in similar-weight crashes, but not against heavier SUVs, pickups, trucks, and buses. image Part 6: 7 advantages of lower speed limit.  1. Safer Car-Pedestrian Collisions The death risk is 4-5 times higher at 50 km/h collisions compared to 30 km/h collisions. Strong recommendation to reduce speed in urban areas. Over 50 km/h is unacceptable in situations where vehicles and pedestrians share space. Preference for a 30 km/h limit in residential areas. Speeds over 5 km/h in urban areas and 10 km/h in rural areas double the risk of a crash (source). Lower Speeds Impact on Crash Survival. Pedestrians have 90% chance of survival at 30 kmph (source). Survival rate decreases to 70% at 40 kmph and less than 20% at 50 kmph (source). image  1. Safer Car-Pedestrian Collisions Pedestrians have 90% chance of survival at 30 kmph (source). Survival rate decreases to 70% at 40 kmph and less than 20% at 50 kmph (source). photo 2. Lower speed increase field vision Central vision is what we see from the front windshield such as roads, vehicles, traffic signs, etc. The central vision field is where we get most visual information while driving. Peripheral Vision is what we see from the corners of our eyes when we look straight. Peripheral vision makes us see potential hazards before they enter our central vision. Images (1, 2) 2. Lower speed increase field vision Every 1.6 kilometer-per-hour reduction in vehicle speeds on urban streets reduces traffic fatalities by 6%. High speeds cause tunnel vision and decreased depth perception. Lower speeds provide a wider field of vision, increasing driver awareness of other road-users. sources (1, 2)  3. Lower speed enable drivers to stop safely High-speed driving leads to shorter reaction times, reduced maneuverability, and larger stopping distances, as shown in Figure 2.2. (see here for more info). This increase chance of accident and endanger driver users. Speeding and reacting to road conditions become riskier during rainy or foggy weather conditions or hazards, heavy traffic, or the presence of curves, pedestrians, or cyclists. image  4. Lower speed increase pedestrian and cyclist safety Lowering vehicle speeds to 30 km/h for pedestrians and no more than 50 km/h on non- grade separated streets. Pedestrians have 90% chance of survival at 30 kmph. Survival rate decreases to 70% at 40 kmph and less than 20% at 50 kmph.  4. Lower speed increase pedestrian and cyclist safety image 5. Lower Speed Reduce Mobility (but not as much as we think !) Lower speed limits reduce congestion and bottlenecks. Lower speed limits can achieve uniform speeds and reduce dangerous midblock acceleration. Research from Grenoble, France, shows a 30 kmph (18.64 mph) limit added to 18 seconds of travel time between intersections. Sao Paulo's implementation of a 10 percent decrease in congestion and fatalities after lowering the speed limit on major arterials. image 6. Lower speeds improve community health and social life. Lower car speeds create a comfortable environment for pedestrians and cyclists. Lower driving speed encourage people to walk, take public transit or cycle which increase chances for communication and socializing with other. Street design encouraging safer speeds includes narrower lanes, wider sidewalks, raised crosswalks, and curb extensions. Speed-slowing infrastructure can lead to positive trends in residents walking or biking. London is implementing measures to encourage walking, predicting health and economic benefits. Regular walking could save $5.6 billion in healthcare costs in the US. Reduced car trips lead to fewer harmful emissions and fewer traffic collisions. 7. Lower Speeds improve economy Streets with pedestrian and cyclist-friendly designs are more vibrant and economically successful. Benefits include increased real estate value and higher retail and service spending. San Francisco's Mission District saw 60% increased local spending and 40% overall sales from narrower lanes. London's Kensington Street saw a 13% increase in apartment prices due to safety and design improvements. Better pedestrian shopping access can generate millions in retail spending. Research indicates that slowing down can improve city dweller quality of life. Read this article about the importance of seatbelts from Physical point of view: Physics behind road crashes - The Road Safety Guy Road Safety Audit A Road Safety Audit is a thorough examination of a road project, conducted by a qualified team, to assess its crash potential and safety performance. It aims to identify safety concerns early in the design process and minimizes risk and severity of crashes on new roads. The audit results in a written report, outlining identified safety issues and practical recommendations for mitigation. Road safety audit is not a crash hotspot programs that aim to reduce observed crashes, relying on historical crash records. So, road safety audit does not rely on crash historical data. Source: Saudi Highway Code, https://istitlaa.ncc.gov.sa/ar/transportation/mot/saudihighwaycode/Doc uments/SHC%20603%20final.pdf Who Does Road Safety Audit? A Road Safety Audit is a formal process conducted by independent, trained auditors to assess road safety issues in road designs, traffic management plans, newly completed or existing roads. A thorough Road Safety Audit report clearly reports safety concerns and offers practical recommendations, while adhering to relevant standards doesn't guarantee a safe road. Source: Saudi Highway Code:  Road Safety Audit The objective of road safety audit is to minimizes risk and severity of crashes on new roads. Road safety audit is a thorough report reporting all safety concerns. Road safety audit offers realistic and practical recommendations to reduce safety concerns. Road safety audit is a proactive process, preventing first crash on new roads. Crash hotspot (different from safety audit) programs aim to reduce observed crashes, relying on historical crash records. Source: Saudi Highway Code, https://istitlaa.ncc.gov.sa/ar/transportation/mot/saudihighwaycode/Docume nts/SHC%20603%20final.pdf  Steps of Road Safety Audit Source: Saudi Highway Code: https://istitlaa.ncc.gov.sa/ar/transportation/mot/saudihigh waycode/Documents/SHC%20603%20final.pdf  Road Safety Audit Checklists Source: Saudi Highway Code, https://istitlaa.ncc.gov.sa/ar/transportation/mot/saudihig hwaycode/Documents/SHC%20603%20final.pdf  Pedestrian Road Safety Audit Checklists (pages 335-336) Source: Saudi Highway Code, https://istitlaa.ncc.gov.sa/ar/transportation/mot/saudihig hwaycode/Documents/SHC%20603%20final.pdf  Pedestrian Road Safety Audit Checklists Source: Saudi Highway Code, https://istitlaa.ncc.gov.sa/ar/transportation/mot/saudihig hwaycode/Documents/SHC%20603%20final.pdf TTENG 564: Recent Advanced in Trans. & Traffic Engineering Lecture 5: Transport Congestion Learning Objectives: Define transport congestion. Identify types transport congestion. Identify causes and effects of transport congestion. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Main Challenges of Transportation Transport Congestion Transport Emissions Transport Safety TTENG 564: Recent Advanced in Trans. & Traffic Engineering What is the main function of transportation? Transportation main function (role/purpose) is to facilitate the movement of people and goods and to provide access to land use activities located within the service area. image See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering What is transportation congestion? Transportation facilities (e.g., walkways, stairways, roads, busways, railways, etc.) is considered congested when demand for their use exceeds their capacity. Congestion happens when volume- to-capacity ratio exceeds 1 (i.e., facility is used above design Image: Example of measuring congestion level for highways capacity). See (1, 2, 3) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering How traffic congestion impact your life? Waste time: Increase your travel time. Deteriorate health: E.g., air pollution and stress. Affects major decisions: E.g., where you work and live. Waste money: Cost of delivery and taxi services. See (1) at the end of the section. image TTENG 564: Recent Advanced in Trans. & Traffic Engineering Is no congestion at all is good? Congestion is sign of economic prosperity. Travel demand is derived from social and economic activities. A city with no congestion is probably unattractive economically, has a declining population or some other issues. However, too much congestion can be a problem, and makes cities less desirable. Therefore, the goal is not to eliminate congestion but to control it. image See (1) at the end of the section.  Relationship between Transportation & TTENG 564: Recent Advanced in Trans. & Traffic Engineering Population Density Better Ability to live Lower Faster travel further from population Transportation modes activities. density Technology Advancements in transportation technology (e.g., electric streetcars, subways, automobiles) result in faster modes that make people live further from their activities. See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Relationship between Transportation & Population Density Better Transportation Ability to live further Lower population Faster travel modes Technology from activities. density Advanced transportation modes increase speeds substantially which made people travel farther within the same travel time budgets (time allocated for travel). This results in the following: (4) reduced (5) increase (6) more (2) the (3) expanded population driving and traffic (1) increased separation of the amount density in reduce emissions mobility. various of urbanized central walking and and so many activities. land. areas. cycling. other effects. See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Relationship between Transportation & Population Density Pedestrian based Electric transit Automobile based (high based (low density/dispersed) density/compact) (medium density) Population 3 millions 3 millions 3 millions Area (square mile) 30 200 500+ Density (person/sq. mile) 100,000 15,000 6,000 Number of jobs in city center 200,000 300,000 150,000 Example Paris pre-1900 Chicago 1930 Dallas 1990 See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Relationship between Transportation & Population Density Before advancement in transportation technology, land travel was by foot (2–3 mph) or by the use of animal power (horse speed of 4–6 mph). Distance one could cover within acceptable travel times was very short and for this reason land use activities were located close together. People seem to value travel time more than travel distance. For instance, people generally accept living far (long distance) from their activities as long they won't spend more time traveling. See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Congestion Causes of Transportation TTENG 564: Recent Advanced in Trans. & Traffic Engineering (1) Large concentrations of demand in time and space Large concentrations of demand in time and space: the problem is that people traveling to the same place at the same time. “If all travel demand were evenly distributed among the various sections of the urban area, the traffic congestion problem would be a rare event. Similarly if all travel were evenly distributed to each hour of the day there would be little, if any,congestion.” TTENG 564: Recent Advanced in Trans. & Traffic Engineering (2) Traffic demand that exceeds roadway capacity Traffic demand that exceeds roadway capacity: Imbalance between supply and demand of transportation facilities). Growth in population, employment, and car use (vehicle miles of travel—VMT) increase congestion on streets and highways where capacity growth has not kept pace with growth in VMT. TTENG 564: Recent Advanced in Trans. & Traffic Engineering (3) Physical and operational bottlenecks Physical and operational bottlenecks: Convergence of a greater number of lanes in the upstream roadways than are available in the downstream roadway. Bottlenecks are also created by roadway incidents that reduce block travel lanes and restrict traffic flow, or they are created by bad weather conditions (e.g., ice on a bridge), a work zone, poorly timed traffic signals, or driver behaviour. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Congestion Types of Transportation TTENG 564: Recent Advanced in Trans. & Traffic Engineering Types of Congestion Recurring congestion(expected): regular delay such as morning and evening rush hours, bottlenecks or bad signal timing. Non-recurring congestion (surprising): non-predictable delay caused by random events such as vehicle accidents, work zones, special events or adverse weather conditions. image See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Congestion can be described precisely by four aspects: Congestion intensity, which reflects the amount of congestion expressed as a rate (e.g. minutes/mile). Congestion duration, which refers to the amount of time the road/system is congested. Congestion extent, which describes the miles of roads that are congested, or the number of travellers affected by the congestion. Image: Example of measuring congestion level for highways Congestion variability, which measures the variation in the amount, duration, and extent of congestion over time. See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Congestion Solutions for Transportation TTENG 564: Recent Advanced in Trans. & Traffic Engineering Solutions for Road Congestion: (1) increasing supply or/and (2) reducing demand More Supply (increase capacity) Building more roads. Increase efficiency (better signal timing). Apply Intelligent Transportation System ITS). Less Demand: Improve other modes. Congestion and parking pricing. Vary time of activities (remember congestion is high demand on the same space at the same time). See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Emerging Solutions for Road Congestion Intelligent Transportation Systems (ITS) Examples of ITS applications ITS strategies entail use of real-time traffic information that Non-stop toll collection allows dynamic traffic signal controls, better traveler This can reduce delay and increase mobility as passengers do not information, roadside electronic screening programs, need to spend time paying the toll. integrated corridor management, and vehicle-infrastructure integration (VII). Traveller Information System Provide travelers with real-time accurate information on roadway traffic congestion and advice on alternative routes reduce trip delays and increases mobility. Roadside Electronic Screening/Clearance Programs for Commercial Vehicles image Speed harmonization: Reducing speeds in advance of a major bottleneck to minimize the impact of the congestion event and increase overall throughput (e.g., Variable Speed Sign (VSS)). See (1) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Why traffic congestion is complicated? 1. Transport demand is a mean not a goal: Most people do not travel for the purpose of driving. This makes demand difficult to predict as people use transport to do their activities all the time. In addition, demand is difficult to predict for random events. In cases such as natural disasters or big events people would use transport at the same space and time which usually create congestion. image See (4) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Why traffic congestion is complicated? 2. Transport demand is variable: with different peak hours during the day. This irregularity is challenging for the efficiency of road infrastructure. For instance, it would be expensive to design a road according to peak hour volume. Transport high and low demand use the same fixed supply of roads. Building too many roads is expensive while building too few is a recipe for congestion. image See (4) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Why traffic congestion is complicated? 3. Driving is so attractive: This increases transport demand. Driving is associated with comfort, privacy, autonomy and security but at the same time causes congestion, emissions and accidents. image See (4) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Why traffic congestion is complicated? 4. Interference with other transport objectives: Transportation has many objectives alongside mobility such as low emission rate, high safety, etc. When we increase mobility (reduce congestion) we might reduce safety and emission rate at the same time. This makes it hard to balance between all three objectives. image See (4) at the end of the section.  Resources TTENG 564: Recent Advanced in Trans. & Traffic Engineering 1. Falcocchio, J. C., & Levinson, H. S. (2015). Springer Tracts on Transportation and Traffic Road Traffic Congestion : A Concise Guide. https://link.springer.com/book/10.1007/978-3-319-15165-6 2. Levels of Service for Road Transportation. https://transportgeography.org/contents/methods/transport-technical-economic-performance- indicators/levels-of-service-road-transportation/ 3. Transportation Research Board (1994) Highway Capacity Manual, 3rd Edition 4. Traffic congestion: the problem and how to deal with it by Alberto Bull https://repositorio.cepal.org/items/ee4d0d10-b15b-4a55-8ded-6887ecedb6d3 TTENG 564: Recent Advanced in Trans. & Traffic Engineering Lecture 6: Traffic Learning Objectives: Shockwaves Explain shockwaves and their impact on traffic. Identify different types of shockwaves. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Time-Space Diagram A time–space diagram is commonly used to solve several transportation-related problems. A time–space diagram shows time at the horizontal axis and distance at the vertical axis. The trajectories of individual vehicles are shown as sloping lines and stationary vehicles are represented by horizontal lines. image See (7, 8) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Time-Space Diagram The slope of the line represents the speed of the vehicle (Rise / Run). Curved portions of the trajectories represent vehicles undergoing speed changes such as deceleration or acceleration. Time-space diagram is useful for analysis of shockwaves and wave propagation. image See (7, 8) at the end of the section.  TTENG 564: Recent Advanced in Trans. & Traffic Engineering See (9) at the end of the section. image Time-Space Diagram TTENG 564: Recent Advanced in Trans. & Traffic Engineering Greenshield’s Model Greenshield developed a model for uninterrupted traffic flow that can reproduce observed in real traffic flows. While Greenshield’s model is not perfect, it is fairly accurate and relatively simple. Greenshield’s model says that under uninterrupted flow conditions, speed and density are linearly related. image See (12) at the end of the section.  Greenshield’s Model TTENG 564: Recent Advanced in Trans. & Traffic Engineering 𝑢𝑓𝑟𝑒𝑒 When the density is zero, the flow is zero because Speed no vehicles are on the roadway. (u) As the density increases, the flow also increases to some maximum flow conditions. 𝑘0 Density (k) 𝑘𝑗𝑎𝑚 When the density reaches a maximum, generally called jam density, the flow must be zero. Speed 𝐮𝐟 Velocity at max flow = half of free flow velocity = (u) 𝟐 𝐤𝐣 Flow (q) Density at max flow = half of jam density = 𝑞𝑚𝑎𝑥 𝟐 image See (12) at the end of the section. TTENG 564: Recent Advanced in Trans. & Traffic Engineering Conservation Law (in = out) Vehicles leaving region 1 = Vehicle entering region 2