Transportation Engineering

Foundational Principles of Transportation Engineering

Understanding the Core Role and Scope

• Grasp the fundamental importance of transportation systems in societal development, economic growth, and environmental sustainability.
• Identify the diverse components of a modern transportation system, including infrastructure, vehicles, and operational control elements across various modes.
• Examine the interdisciplinary nature of transportation engineering, recognizing its connections to civil engineering, urban planning, economics, and environmental science.

Economic, Social, and Environmental Impacts

• Analyze the economic benefits of efficient transportation, such as enhanced trade, job creation, and increased accessibility to markets.
• Evaluate the social implications of transportation infrastructure, including community severance, equitable access, and public health considerations.
• Assess the environmental consequences of transportation, covering air quality degradation, noise pollution, land use changes, and greenhouse gas emissions.
• Learn methods for mitigating negative impacts and promoting sustainable transportation practices.

Geometric Design of Highways

Design Controls and Criteria

• Apply standard design controls such as design speed, traffic volume, vehicle characteristics (e.g., design vehicle dimensions), and terrain to highway design.
• Understand the importance of driver characteristics, including perception-reaction time and visual acuity, in determining appropriate design parameters.

Sight Distance Requirements

• Calculate and apply stopping sight distance (SSD) for various grades and speeds, ensuring drivers have sufficient distance to stop safely.
• Determine passing sight distance (PSD) on two-lane highways, considering opposing traffic and the dynamics of overtaking maneuvers.
• Implement decision sight distance (DSD) principles for complex situations like interchanges, providing drivers adequate time to perceive information, make decisions, and execute maneuvers.
• Evaluate the impact of roadside obstructions and horizontal/vertical curves on available sight distance.

Horizontal Alignment Design

• Design horizontal curves using radius, deflection angle, and tangent length, ensuring smooth transitions for vehicles.
• Calculate and apply super-elevation (banking) to counteract centrifugal force on curves, maintaining vehicle stability and driver comfort.
• Design transition curves (spirals) to provide a gradual change in curvature and super-elevation between tangent sections and circular curves.
• Understand the relationship between super-elevation, curve radius, and design speed.

Vertical Alignment Design

• Design vertical grades that account for vehicle performance, drainage, and safety.
• Design crest vertical curves to provide adequate stopping sight distance over the crest.
• Design sag vertical curves to ensure proper headlight sight distance at night and manage drainage effectively.
• Apply K-values for different design speeds to determine appropriate curve lengths for both crest and sag curves.

Cross-Sectional Elements

• Specify lane widths, shoulder widths, and median designs based on functional classification and design volume.
• Design roadside clear zones to enhance safety by providing traversable areas for errant vehicles.
• Incorporate drainage elements such as ditches, culverts, and inlets to manage stormwater runoff effectively and protect the road structure.
• Understand the function and design of auxiliary lanes, such as turning lanes, acceleration lanes, and deceleration lanes.

Traffic Engineering Principles and Applications

Traffic Flow Theory

• Understand the fundamental relationships between traffic speed, density, and volume, including their graphical representations.
• Apply macroscopic and microscopic traffic flow models to analyze traffic behavior on roadways.
• Interpret key traffic flow parameters such as free-flow speed, jam density, and capacity.

Traffic Studies and Data Collection

• Conduct various traffic studies, including volume counts (ADT, AADT, peak hour volume), speed studies (spot speed, travel time), and origin-destination studies.
• Design and implement parking studies to assess demand and supply, and develop parking management strategies.
• Analyze data collected from traffic studies to identify operational issues and inform design decisions.

Highway Capacity Analysis

• Apply methodologies from the Highway Capacity Manual (HCM) to determine the operational performance and capacity of various highway facilities.
• Analyze the capacity and level of service (LOS) for basic freeway segments, weaving sections, ramps, and signalized/unsignalized intersections.
• Identify factors affecting capacity, such as lane width, heavy vehicles, driver population, and geometric features.

Traffic Control Devices and Operations

• Design and apply traffic signs (regulatory, warning, guide) according to Manual on Uniform Traffic Control Devices (MUTCD) standards.
• Specify pavement markings for various purposes, including lane delineation, turn arrows, and crosswalks.
• Design traffic signal timings and phasing plans for isolated intersections and coordinated arterial systems to optimize flow and minimize delay.
• Understand the principles of actuated and pre-timed signal operations.

Traffic Safety and Accident Analysis

• Analyze accident data to identify high-crash locations and contributing factors.
• Calculate various accident rates (e.g., crash rate per million vehicle miles, severity rate).
• Develop and evaluate safety countermeasures for different types of crashes, such as intersection improvements, roadside safety features, and traffic calming measures.
• Understand the principles of road safety audits and their role in proactive safety management.

Transportation Planning and Demand Forecasting

Urban Transportation Planning Process

• Understand the multi-stage, comprehensive, and continuous nature of the urban transportation planning process.
• Apply the traditional four-step travel demand model: trip generation, trip distribution, mode choice, and trip assignment.
• Identify the data requirements for each step of the planning process and appropriate data collection methods.

Travel Demand Modeling Techniques

• Perform trip generation analysis using regression models and cross-classification to estimate the number of trips produced and attracted by zones.
• Apply trip distribution models, such as the gravity model and the Fratar method, to estimate origin-destination trip tables.
• Implement mode choice models (e.g., logit models) to predict the proportion of trips using different transportation modes based on socioeconomic factors and travel costs.
• Execute trip assignment techniques (e.g., all-or-nothing, equilibrium assignment) to load trips onto a transportation network and predict link volumes.

Land Use and Transportation Interaction

• Examine the reciprocal relationship between land use patterns and transportation demand.
• Understand how land use policies can influence travel behavior and vice versa.
• Explore concepts like Transit-Oriented Development (TOD) and Smart Growth strategies.

Forecasting Techniques and Network Planning

• Apply various forecasting methods to predict future travel demand, population growth, and economic activity relevant to transportation planning.
• Develop and evaluate alternative transportation plans and network improvements based on performance measures and policy objectives.

Pavement Design and Materials

Pavement Structure and Types

• Differentiate between flexible pavements (asphalt concrete) and rigid pavements (Portland cement concrete) in terms of structural behavior and material composition.
• Identify the layers within each pavement type (e.g., surface course, base course, subbase, subgrade) and their respective functions.

Material Properties and Characterization

• Understand the properties of aggregates (size, shape, strength) and their impact on pavement performance.
• Characterize asphalt binders (viscosity, penetration, PG grading) and their role in flexible pavements.
• Analyze the properties of Portland cement concrete (strength, durability, shrinkage) for rigid pavements.
• Evaluate subgrade soil properties using tests like California Bearing Ratio (CBR), R-value, and resilient modulus to determine its support capacity.

Pavement Design Methods

• Apply empirical design methods, such as the AASHTO Guide for Design of Pavement Structures, to determine pavement layer thicknesses based on traffic, materials, and environment.
• Understand the principles of mechanistic-empirical pavement design, which integrates material response models with empirical distress prediction.
• Consider factors like traffic loading (Equivalent Single Axle Loads - ESALs), environmental conditions (temperature, moisture), and material strength in design calculations.

Pavement Distress and Rehabilitation

• Identify common types of flexible pavement distresses (e.g., rutting, fatigue cracking, thermal cracking, potholes).
• Recognize common rigid pavement distresses (e.g., faulting, spalling, joint deterioration, pumping).
• Develop appropriate rehabilitation strategies based on distress type and severity, including overlays, patching, recycling, and reconstruction.

Public Transportation and Non-Motorized Modes

Public Transit System Characteristics

• Categorize different public transit modes, including bus systems (local, express, BRT), rail systems (light rail, heavy rail, commuter rail), and specialized services (paratransit, demand-responsive transit).
• Understand the operational characteristics, capacities, and service requirements of each transit mode.

Transit Planning and Operations

• Apply methods for transit route planning, scheduling, and frequency determination to meet demand.
• Analyze fare structures, ridership models, and service performance metrics for transit systems.
• Evaluate the effectiveness of transit priority treatments, such as dedicated bus lanes and signal preemption.

Bicycle and Pedestrian Facilities Design

• Design safe and accessible bicycle facilities, including on-street bike lanes, separated cycle tracks, and multi-use paths.
• Plan and design pedestrian infrastructure, such as sidewalks, crossings (at-grade and grade-separated), and accessible ramps.
• Implement principles of complete streets and Vision Zero to enhance safety and comfort for non-motorized users.

Accessibility and Multimodal Integration

• Incorporate Americans with Disabilities Act (ADA) requirements into the design of transit facilities and pedestrian infrastructure.
• Develop strategies for seamless integration between different transportation modes (e.g., park-and-ride facilities, bike-and-ride options, transit hubs).

Emerging Topics and Sustainable Transportation

Intelligent Transportation Systems (ITS)

• Understand the various components of ITS, including Advanced Traveler Information Systems (ATIS), Advanced Traffic Management Systems (ATMS), Advanced Public Transportation Systems (APTS), and Advanced Vehicle Control Systems (AVCS).
• Explore how ITS technologies are used for real-time traffic monitoring, incident management, electronic toll collection, and dynamic message signs.
• Analyze the potential of connected and autonomous vehicles to transform transportation systems.

Sustainable Transportation Planning

• Apply principles of sustainable transportation to reduce environmental impact, promote social equity, and ensure economic viability.
• Evaluate strategies such as transportation demand management (TDM), congestion pricing, and alternative fuel vehicle adoption.

Data Analytics in Transportation

• Utilize large datasets from various sources (e.g., sensors, GPS, mobile phones) to analyze travel patterns, optimize operations, and predict future trends.
• Apply statistical methods and visualization tools to extract actionable insights from transportation data.