A Comprehensive Guide to Transportation Engineering

20 min. Read • Posted 08/08/2024 by Monique Fuhrman, P.E.

What is transportation engineering and why does it matter?
What do Transportation Engineers do?
The history of transportation engineering
Key terms to know
Real-world examples
Tips and best practices
Common questions about transportation engineering
Transportation engineering challenges
Design and deliver with confidence

Transportation engineering is a foundational practice within civil engineering that directly impacts how people, goods, and data move within and between communities by designing and implementing improvements to the transportation networks that serve our daily lives. Transportation engineering combines industry best practices, high standards, state-of-the-art technology, and the professional judgment of licensed and experienced engineers to deliver projects that move people, goods, and data every day.

This guide is for those new to the field, providing an overview of transportation engineering. In this post, we’ll explore its importance, how it works, best practices, and more.

What is Transportation Engineering and Why Does it Matter?

Transportation engineering is a branch of civil engineering that involves the planning, design, delivery, operation, and maintenance of transportation systems and networks that serve our communities. It affects all systems that move people, goods, or services from one place to another. This primarily includes our road and highway networks but also extends to our rail systems, transit systems, traffic control and management systems, connected vehicle/autonomous vehicle systems, and even space travel.

ransportation engineering is largely a data-driven field where engineers deliver projects that aim to improve mobility, safety, economic development, accessibility, and reduce environmental impacts on a transportation network. Using technical knowledge and creative problem-solving skills, engineers will not only design and deliver new infrastructure, but also modify or modernize existing infrastructure to serve the ever-evolving needs of its users.

Transportation engineering matters because it is a crucial part of ensuring that we have safe, efficient, and sustainable ways to move people and goods, which in turn contributes to enhancing economic development and vitality, environmental stewardship, and quality of life for all. At Iteris, we’re passionate about these goals and values—learn more about how our transportation engineering services can help achieve them.

What do Transportation Engineers do?

Transportation engineering is a broad branch under the umbrella of civil engineering which focuses specifically on transportation networks and infrastructure that move goods and people. The following are several types of tasks that are typically performed by transportation engineers:

Designing and delivering transportation infrastructure
Transportation engineers are trained to plan and design the construction of our roads, highways, bridges, tunnels, railways, airports, and transit systems. The design of these systems involves the implementation of vetted industry standards and engineering judgment on such factors as traffic flow, safety, environmental impact (such as greenhouse gas emissions or other biological impacts), and cost-effectiveness.
Traffic engineering
As a subset of transportation engineers, traffic engineers focus specifically on analyzing the flow of traffic. Understanding traffic patterns and driver behavior plays a large part in determining how to optimize traffic flow and reduce congestion. Traffic engineers typically design intersections, traffic signals, signage and pavement markings, and systems which help to improve traffic flow, efficiency, and safety.
Public transportation planning and design
Transportation engineers frequently work with transportation planning professionals to plan and design public transit systems like buses, commuter trains, light rail, and subways. Transportation engineers not only design and deliver the infrastructure that serves these modes of transportation but also contribute to the determination of routes and schedules to provide effective service to the users.
Safety improvements
The paramount goal of all transportation engineering is to provide safe and efficient transportation to all goods and people. Thus, transportation engineers focus on the improvement of safety for all modes, including pedestrians, bicyclists, and motorists. While there has always been a rigorous focus on safety, recent years have seen most government transportation agencies placing a heavy emphasis on Vision Zero, a movement toward reducing traffic fatalities and severe injuries to zero. To aid in this effort, transportation engineers may conduct safety audits, implement traffic calming measures, and redesign infrastructure to create safer crossings and facilities that protect more vulnerable users.
Environmental impact assessments
Part of delivering large transportation projects is assessing the overall environmental impact of the project. Transportation engineers support this effort by assessing and developing strategies to minimize pollution, noise, and habitat disturbance, thereby improving the sustainability of the project. In fact, many transportation engineering projects have reduction of carbon emissions as primary goal of the project.
Infrastructure maintenance and management
Once projects are built and infrastructure is operating, transportation engineers oversee the ongoing maintenance and periodic rehabilitation of that infrastructure. Transportation engineers are responsible for developing maintenance plans, performing inspections, and determining what repairs or upgrades may be needed to ensure the infrastructure is safe for continued use. This work keeps our systems operational and works to extend the useful life of the infrastructure, protecting the significant investments that were made to build it.
Transportation policy and regulation
Transportation engineers and professionals play an influential role in the development of policies, regulations, and standards at all levels of our government. They advise policymakers who are developing laws, codes, or guidelines, and help to ensure compliance with those requirements following implementation.
Implementing emerging technologies
As transportation technology advances, transportation engineers work to integrate innovations into our transportation system. Innovations which have successfully been implemented include intelligent transportation systems (ITS), autonomous and connected vehicles, electric vehicles, and even detection and data collection systems.
Community engagement
Transportation engineers collaborate with many different types of stakeholders in the implementation of their work, including government agencies, developers, advocacy groups, and the public to understand needs, address concerns, and to ensure that projects can meet the needs of the ultimate users.

The History of Transportation Engineering

Transportation engineering is one of the oldest disciplines of engineering dating back to ancient civilizations. As human societies and economies developed over time, the importance of goods and services grew, creating the need to move and distribute said goods and services.

We can see evidence of roads, bridges, and water transport systems as early as 3000 B.C. in places like Mesopotamia, Egypt, and Rome. Early engineers further developed their craft in the medieval and Renaissance periods by building even more roads to connect their cities and canals to transport goods and materials further. Some of this infrastructure endures today!

A key turning point in transportation engineering occurred during the Industrial Revolution of the 18th and 19th centuries with the invention of the steam engine. In addition to the expansion of canals and other traditional modes of the time, the use of locomotive-powered trains paved the way for vast networks of railways to be built, revolutionizing transportation speed and capacity forever.

The 20th century brought the advent of automobiles and aviation. As transportation became a personal commodity, transportation networks had to evolve very quickly. Transportation engineers began focusing on designing modern highways, interstates, and urban road networks to accommodate the growing demand. Even amid the Great Depression in the 1930s, transportation remained a key practice. Iconic transportation projects were built during this time, including the Golden Gate Bridge, the Empire State Building, and the Hoover Dam.

Construction progress of the Golden Gate Bridge (Source: Golden Gate Bridge Highway & Transportation District)

In 1956, President Dwight D. Eisenhower signed the Federal-Aid Highway Act of 1956 which began the lengthy but important process of constructing the United States Interstate Highway system. Not only did those projects create jobs for Americans, many of them transportation engineers, but it paved the way for the transportation network we enjoy today.

In 1996, President Bill Clinton said, “The Interstate Highway Act literally brought Americans closer together. We were connected city-to-city, town-to-town, family-to-family, as we had never been before. That law did more to bring Americans together than any other law this century...”

As we entered the 21st Century, the focus of transportation engineering has shifted to more modes than just rail and automobiles. The diversity and economic growth of the United States saw a renewed interest in public transportation systems as cities and urban areas became more congested.

Technology continues to evolve and influence how transportation engineers design our transportation networks, especially with the advent of GPS, autonomous vehicles, and intelligent transportation systems (ITS). Today transportation engineers’ focus remains forward-facing, with an emphasis on sustainability, reducing emissions, improving efficiency, and promoting more sustainable modes of transportation.

As you can see, transportation engineering has always played a role in the evolution of society and continues to evolve along with technological innovations, societal needs, and economic developments (or depressions), always contributing to shaping the physical and social landscapes of our communities.

Key Terms to Know

Understanding key terms is essential for grasping the nuances of transportation engineering. Here are a few important ones:

Vision Zero: A global safety initiative that aims to reduce traffic fatalities and severe injuries to zero. The concept originated in Sweden in the 1990s, started to gain traction in the US in the early 2000s, and has now been adopted by numerous agencies throughout the US.
Multi-modal: In general, multi-modal refers to the different types of transportation modes that may be integrated into a single network or system. Common modes in transportation engineering include automobiles, bicycles, or other micromobility options like scooters or e-bikes, pedestrians, and transit.
Intelligent Transportation Systems (ITS): Advanced technologies and methodologies such as traffic management systems, real-time information systems, integrated corridor management, and vehicle-to-infrastructure communication, that aim to improve efficiency, safety, and sustainability on transportation networks.
Infrastructure: The system of public works which provides a foundation or framework for transportation. This broad term could include roadways, highways, bridges, tunnels, utilities, communications, canals and waterways, etc.
Capacity: The physical limit to the number of people or vehicles that can pass through a transportation facility within any given amount of time. In transportation or traffic engineering, this is measured as vehicles per hour or persons per hour.
Level of Service (LOS): A qualitative measure that characterizes the operational conditions of a transportation facility or corridor. LOS uses a letter grading scale and some quantitative measurements depending on the facility type to grade how a facility is operating. LOS A generally represents free-flow conditions and little delay, while LOS F represents severely congested conditions.
Intersection: The point where two or more roadways or facilities meet. For safety purposes, most intersections require some type of control such as traffic signals, stop signs, or roundabouts to promote and facilitate the safe movement of traffic through the intersection.
Roadway or Geometric Design: The process of designing roads, highways, and streets to ensure safe and efficient movement of traffic. Design typically considers factors such as alignment, lane width, curvature, sight distance, and superelevation to provide smooth travel for users.
Traffic Control Devices: General term for the various types of signs, signals, and markings that regulate, warn, and guide traffic on the transportation network. In the US, devices are universally governed by the Manual for Uniform Traffic Control Devices, ensuring that interstate traffic and users can safely navigate our vast transportation network.
Transportation Planning: The process of evaluating current and future transportation needs and developing strategies and policies to address them, including land use planning, demand forecasting, and infrastructure investment planning.
Public Transit: Modes of transportation that are designed to move larger numbers of people efficiently. Public transit is especially important in large urban centers where large numbers of people need to go to the same already congested places. Public transit can include buses, light rail, subways, commuter trains, and paratransit. Public transit has also expanded recently to include micromobility options, such as scooters or e-bikes, for last-mile connections.
Systems Engineering: A process or methodology often used in transportation engineering and planning for the implementation of projects or technologies to ensure that intended benefits are realized by a project. The process involves the conception of and planning for the design, integration, and management of complex systems over the life cycle of the system. For more information about Systems Engineering, visit the International Council on Systems Engineering website.

Real-World Examples

Here are some practical examples of transportation engineering that Iteris has participated in:

I-405 Design-Build Improvement Project, Orange County, California: As part of a multi-disciplinary design-build team, Iteris supported the I-405 Design-Build Improvement Project which built Express Lanes (i.e., tolled lanes) in Orange County. The project built out additional capacity within an existing freeway footprint and employed emerging technologies and alternate congestion management strategies, such as congestion pricing (e.g., tolling), to help alleviate historically challenging traffic. Along with the design of the various electrical and intelligent transportation systems (ITS), Iteris also led the maintenance of traffic effort, providing innovative traffic management strategies during construction to help manage the real-time congestion due to the construction work during the 5-year construction. This project was successfully completed in 2023 and is currently in operation.d

DMATS Smart Traffic Routing with Efficient and Effective Traffic System (STREETS) Project – Dubuque, Iowa: Together with project partners East Central Intergovernmental Association (ECIA), Dubuque Metropolitan Area Transportation Study (DMATS), and Iowa Department of Transportation, the City of Dubuque initiated this project to implement an advanced integrated traffic signal system for real-time traffic management. To support this project, Iteris led the initial planning stages of the implementation of a series of innovative, next-generation technologies to help with the congestion management. Iteris implemented the FHWA systems engineering process to plan the deployment of a real-time traveler information system that proactively and dynamically balances congestion along key corridors using various refined traffic models and state-of-the-art ITS systems. The ITS systems included Advanced Traffic Management System (ATMS), Advanced Traveler Information Systems (ATIS), and third-party data sources, such as Waze. The project is expected to reduce wear and tear on the roadways by more effectively spreading traffic among the transportation network while also reducing congestion, travel time and delay, and pollution, while also improving safety. The city is moving into the next phase of their STREETS plan to expand this approach further around the City after having been awarded at $2M grant by the Infrastructure Investment and Jobs Act (IIJA) in March 2024 .

Wilshire Bus Rapid Transit Project – County of Los Angeles, California: As part of a multi-disciplinary consultant team, Iteris led the pre-design of the traffic engineering elements of this Bus Rapid Transit (BRT) project which aims to improve bus travel times on one of the County’s most heavily used transit corridors. Iteris prepared the design documentation for lighting, traffic signals, pavement markings, and transit signage to support the improvements along the project route. Upon implementation of the new BRT route and improvements, bus travel times improved by an average of 24%, ultimately resulting in an increase in ridership of up to 20% on the corridor. This project was awarded several awards: the ACEC CA Chapter Merit Award, the ASCE LA Outstanding Transportation Project Award, and the APWA Best Project of the Year – Transportation Award.

Tips and Best Practices

At Iteris, with our over 35 years of experience in transportation engineering, we’ve learned a few key strategies that make a significant difference. Implementation of these best practices requires collaboration among transportation engineers, planners, policymakers, and community members to ensure that our transportation systems are safe, accessible, environmentally responsible, and meeting user needs.

Think ahead, be proactive. Effective transportation planning lays the groundwork for transportation engineering projects and should involve close coordination between urban planners and engineers to design communities that serve all modes of transportation, even going so far as to reduce the need for car trips. In addition to building these projects, consideration must also be given to the ongoing operation and maintenance of the projects, ensuring that there is a return on the investment in the project.
Keep safety at the forefront. Always prioritize safety in design by implementing proven measures that reduce the risk of crashes and injuries, including such mitigations as traffic calming measures that reduce vehicle speeds or improve visibility at intersections.
Consider all modes. The Complete Streets Design approach considers the needs of all users, including pedestrians, bicyclists, transit users, and motorists. This could include incorporating features such as wide sidewalks, safe and controlled crossings, bike lanes, and considering accessibility for all.
Harness the power of technology. Where physical improvements may be impossible or undesirable, consider the implementation of technological solutions to enhance efficiency and safety. ITS technologies have proven effective in reducing congestion and managing traffic flow by utilizing real-time traffic monitoring, adaptive signal control, dynamic message signs, and vehicle detection systems. These systems enhance the effectiveness of the existing infrastructure by managing congestion in real-time.
Consider sustainability. Transportation engineers around the world are busy developing and implementing solutions that promote energy-efficient modes of travel and reduce emissions and environmental impact, while ensuring that our transportation network will stand the test of time. This includes social elements such as transportation equity.

By following these tips, you can develop effective, sustainable, and safer transportation projects. For additional guidance, check out NACTO’s publications for best practices.

Common Questions about Transportation Engineering

How does transportation engineering impact daily life? Most people interact with the product of transportation engineering daily. Did you go for a walk? A transportation engineer designed the sidewalk you likely used. Did you drive to work or school? A transportation engineer designed the freeway you took or the traffic signal you stopped at. Did you fly to another country for vacation? A transportation engineer designed the airport and runway the plane will use to take off. Transportation engineers design all infrastructure that is used to move goods, people, and services.
How does transportation contribute to environmental sustainability? Transportation projects generally seek to provide better, more efficient ways to move people and goods throughout the world. This means building networks that can accommodate and occasionally prioritize sustainable modes of transportation such as walking, biking, and transit. The reduction of vehicles on our transportation network generally reduces emissions, aiding in the global environmental sustainability mission.
What role does technology play in transportation engineering? Technology is a huge player in transportation, providing new innovative ways to solve complex issues that previously might have been solved by expanding facilities and infrastructure. Technology such as ITS, autonomous vehicles, and data analytics provide engineers the opportunity to improve efficiency of people and goods movement quickly and more easily than a traditional infrastructure expansion project. These technologies are shaping the future of transportation engineering.
How do transportation engineers plan for future growth and development? A key element and predecessor of transportation engineering is transportation planning . During the planning and conception phases, engineers and planners forecast such metrics as population growth, urban expansion, and economic changes using large amounts of historical data to approximate the need for transportation facilities and projects, allowing engineers to implement measures that will address projected or potential changes to users’ needs in the future. Additionally, once projects are developed and built, transportation engineers facilitate the ongoing performance measurement and maintenance of the infrastructure, ensuring that the infrastructure continues to be safe for all users and that the investment in the project is preserved.
What are Complete Streets and why are they important? Complete Streets are roadways and facilities that prioritize safety and accessible infrastructure for all modes (pedestrians, bicyclists, transit, automobiles, and freight). Complete Streets offer a proven methodology to implement improvements that benefit everyone and that can still serve all as users’ needs evolve.

Transportation Engineering Challenges

Transportation engineering is driven by ever-evolving societal needs, technological advances, and expanding environmental concerns and thus is subject to various types of challenges.

Technical Challenges

Congestion and changing travel patterns: Traffic congestion remains a persistent issue in urban areas worldwide. As congestion increases, so does the amount of wasted time, fuel consumption, air pollution, and economic loss. Addressing congestion requires innovative solutions and creative demand management strategies.
Safety: Despite improvements in vehicle safety and roadway design methodologies, traffic-related injuries and fatalities continue to be a major concern. Vision Zero and prioritizing addressing safety issues must continue to be at the forefront of any project.
Maintenance and rehabilitation of infrastructure: As our infrastructure ages, the need for maintenance and rehabilitation increases substantially. Funding constraints and competing priorities can and have hindered efforts to keep our transportation networks in good condition.

Environmental Challenges

Emissions: Transportation is a significant contributor to air pollution globally. Addressing the impacts of greenhouse gas emissions has become a key priority, with engineering projects focusing on promoting sustainable transportation options and reducing our reliance on fossil fuels.

Institutional Challenges

Regulatory challenges with emerging technologies: As rapid advancements in technology come to light, our institutions are working hard to develop regulatory frameworks that ensure that new technologies such as autonomous vehicles, electric vehicles, and smart transportation systems can navigate the transportation environment safely. Occasionally these regulations, or the waiting for regulatory oversight, make implementation of new technology take longer in the interest of protecting the public and our transportation network from adverse effects.
Funding: Adequate funding for transportation infrastructure and services is critical but often limited. Prioritizing transportation investments can be challenging when there are many competing budgetary demands.

Societal Challenges

Equity and Accessibility: A growing focus has been placed on transportation’s role in social equity. Ensuring projects account for the needs of all, including disadvantaged communities who may have limited access to affordable transportation, is an important element of any modern transportation project.

As noted previously, addressing these challenges requires a multi-disciplinary approach among all: planners, designers, owners, stakeholders, community members, and end users. It is through innovative and creative collaboration that we can create transportation systems that are safe, efficient, sustainable, and equitable for all.

Design and Deliver with Confidence

Transportation engineering plays a pivotal role in shaping the mobility, safety, and sustainability of our communities, making it a dynamic and indispensable field. Our local municipalities, regional transportation authorities, and metropolitan planning organizations are constantly working to keep up with the growing and evolving demand on our transportation systems.

If your organization is ready to improve your community's transportation systems by delivering innovative and sustainable transportation projects, contact Iteris for a consultation or to learn more about our transportation engineering services.

A Few Key References

Federal Highway Administration. (n.d.) Resources. https://www.fhwa.dot.gov/resources/topics/
American Association of State Highway and Transportation Officials. (n.d.)Publications.https://store.transportation.org/
National Association of City Transportation Officials. (n.d.). Publications. https://nacto.org/publications/
Institute of Transportation Engineers. (n.d.). Traffic Engineering Handbook. https://ecommerce.ite.org/IMIS/ItemDetail?iProductCode=LP-691