Reference our Glossary for definitions and context for terms, concepts and acronyms used throughout 2040 & Beyond. On this page, you can also find information about current and past plans, and link to RTPO & MPO websites.

Glossary of Useful Terms, Concepts & Acronyms

WTP 2040 and Beyond is full of terms that are specific to transportation, or common terms used in specific ways when thinking about transportation. This Glossary is a collection of terms found throughout the plan that may be unfamiliar to readers, or which merit clarification as to how they’re used in this plan, including common acronyms for those terms.

Autonomous Vehicles | AV

An autonomous vehicle is one that can drive itself effectively in autopilot mode from a starting point to a predetermined destination using various in-vehicle technologies and sensors. Humans play a very limited role, if any, in the driving process. AVs include passenger vehicles, trucks, and transit vehicles as well as emerging vehicles designed for particular mobility functions like package deliveries (e.g. drones, robotic delivery devices). Automated vehicles are undergoing rapid technological advancements and generate widespread interest both for their potential benefits and their potential downsides or unintended consequences for system mobility.


Broadband refers to a variety of techniques for delivering high-capacity data transmission. It typically means high-speed internet access that is “always on,” as opposed to dial-up access, for example, DSL and 4G cellular service. While there are differing opinions as to whether broadband is actually the transportation system for information, there is no doubt that absent broadband access, few if any transportation technologies are available and opportunities to access services without having to travel are severely restricted. Lack of broadband access limits access to economic and social opportunities enjoyed in communities that do.


Transportation capacity is a measure of how much throughput a system has during a certain amount of time, for example, an hour or a day. How we define system capacity is evolving for the first time in over half a century. Throughout the second half of the 20th century, the primary throughput of concern was the number of motor vehicles. The time period of greatest concern was the evening peak commute period – typically the “rush hour” in most communities but extending to many hours in big ones  Increasingly we’re paying more attention to people throughput or freight throughput, not just vehicle throughput, especially in highly urban corridors. This aligns closer with our values about doing more with the infrastructure and services we have and getting maximum benefit out of our transportation investments. It lets us look at transit in a more balanced way, and better support the transportation-land use connection in so many of our communities. How throughput is defined and capacity is measured is central to any discussion about urban congestion, concurrency, level of service or LOS, system performance, and performance measures, and it has a big influence on what constitutes an effective strategy or project investment. WTP 2040 and Beyond recognizes that how we think about transportation system capacity is evolving. It will be different in the future than the way we think about it now and have thought about it historically. Unless indicated otherwise, the term “capacity” in this plan refers to system capacity with an emphasis on person throughput and freight throughput for situation-specific increments (e.g. hour or 12-hours).

Commute Trip Reduction | CTR

Commute Trip Reduction is an employer-based travel demand management program. Laws relating to commute trip reduction (CTR law) were adopted in 1991 and incorporated into the Washington Clean Air Act. The intent of the CTR law is to reduce automobile-related air pollution, traffic congestion, and energy use through employer-based programs that encourage the use of alternatives to the single-occupant vehicle traveling during peak traffic periods for the commute trip. Strategies such as these that encourage travelers to use the transportation system more efficiently are generally known as transportation demand management (TDM). In 2006, the Legislature amended the CTR law to make the program more efficient and effective.

Comprehensive Plan

The Growth Management Act is a state law that requires local agencies to develop and adopt long-range plans that guide growth and development to achieve community visions and agreed-upon goals and objectives. These perpetual plans are updated periodically. Most have been in place and working to shape community growth for over 20 years. Local Comprehensive Plans must establish adopted Level of Service standards for transportation and be consistent with the long-range Regional Transportation Plan; the Regional Transportation Plan in turn must be consistent with the local plans. This overlapping GMA consistency requirement ensures ongoing coordination between local and regional agencies.


Concurrency is one of the goals of the Growth Management Act. It refers to the timely provision of public facilities and services relative to when they are needed, typically “concurrent” with development. GMA directs special attention to concurrency for transportation. It requires that transportation improvements or strategies to accommodate development impacts need to be made concurrently with land development to maintain adopted Level of Service standards  Improvements or strategies need to be in place at the time of development, or a financial commitment is needed to complete the improvements or strategies within six years. Those Level of Service standards are established as part of the Comprehensive Plan, and are used to determine whether the impacts of a proposed development can be met through existing capacity and/or to decide what level of additional facilities will be required to meet LOS standards. Transportation is the only area of concurrency that specifies denial of development if LOS standards cannot be met. GMA grants local government great flexibility in how they define Level of Service and apply concurrency within their plans, regulations, and permit systems. Note that local jurisdictions cannot require developers to pay for improvement to correct existing deficiencies. Concurrency does not apply to Highways of Statewide Significance.

Congestion Pricing

Congestion pricing - sometimes called value pricing - is a way of harnessing the power of the market to reduce system inefficiencies that contribute to traffic congestion. Congestion pricing works by shifting discretionary rush hour highway travel to other transportation modes or to off-peak periods through pricing mechanisms. By removing a small fraction of the vehicles from a congested roadway (even as small as 5 percent), pricing enables the system to flow much more efficiently and move more people and vehicles through the same physical space. Similar variable charges have been successfully utilized in other industries - for example, airline tickets, cell phone rates, and electricity rates. The Federal Highway Administration finds there is a consensus among economists that congestion pricing represents the single most viable and sustainable approach to reducing traffic congestion. Although drivers unfamiliar with the concept initially have questions and concerns, surveys show that drivers more experienced with congestion pricing support it because it offers them a more reliable trip time than without it. Transit and ridesharing advocates appreciate the ability of congestion pricing to make transit and ridesharing more attractive. Congestion pricing can be applied through a variety of mechanisms. In Washington it is typically applied through variable rate tolls (dynamic tolling) on entire facilities, such as the SR 520 floating bridge, or on specified managed, Express Toll Lanes.

Connected Vehicles | CV

A connected vehicle is one that is equipped with Internet access, and usually also with a wireless local area network. This allows the car to share internet access with other devices both inside as well as outside the vehicle. This includes connectivity and information sharing between the vehicle and things like cell phones and tablets in the vehicle, and with other vehicles (vehicle-to-vehicle), with roadway infrastructure (vehicle- to-infrastructure), and with information systems in the cloud (vehicle-to-cloud). The vast majority of new vehicles come with standard with varying degrees of connectivity. Vehicle connectivity is undergoing rapid technological advancements and generates widespread interest both for the potential benefits and the potential downsides and unintended consequences for system mobility.

Cross-Cutting Topics

Cross-cutting topics refers to a small number of disruptive forces at play that are beyond the control of any one agency or organization and which influence the issues and opportunities we face in meeting our transportation goals. The three topics featured in WTP 2040 and Beyond are:

  • Technology and innovation, which are changing the way we think about and plan for transportation and mobility
  • System resilience, particularly in the face of climate change and extreme weather events but also in terms of earthquakes, tsunamis, and lahar flows
  • Paying for transportation, including changes in revenue sources and funding responsibilities, how projects are prioritized for funding, and the nature of funding partnerships

Each of these topics have implications for all six transportation goals and present uncertainties that must be factored into our decision-making for all aspects of the transportation system.

Demand Management

Demand management is a process to plan for and manage the demand for transportation capacity and services. See Travel Demand Management.

Dynamic Tolling

Dynamic tolling is a congestion pricing mechanism intended to maintain more reliable travel speeds and increase throughput, especially during peak periods of demand. Tolls are continually adjusted according to traffic conditions to maintain smooth traffic flows, with prices increasing as the tolled lane or facility is closer to full, and prices decreasing when the lane or facility is less full. The current price is displayed on electronic signs prior to the beginning of the tolled section. This system is more complex and less predictable than using a fixed-price table, but its flexibility helps to consistently maintain the optimal traffic flow.


Equity refers to the fairness with which benefits and costs are distributed. Transportation equity considerations focus largely on the intersection of community design and access to transportation services and programs, transportation impacts on public health, and access to economic and social opportunities regardless of income, age, ability, race or ethnicity. Transportation equity can be difficult to evaluate because of the various types, impacts, measurement units, and categories of costs and benefits for people to consider.

Essential Public Facilities

Essential public facilities are defined in the Growth Management Act as those facilities that are necessary but typically difficult to site. Transportation facilities falling into this definition include: airports; state or regional transportation facilities; and facilities deemed to be of statewide significance including interstate highways, principal arterials, ferries serving statewide travel, intercity passenger rail services and high-speed ground transportation, the freight railroad system, the Snake-Columbia River navigable waterway system, marine ports serving international or interstate trade, high capacity transportation systems, and regional transit authority facilities. Local jurisdictions can identify additional essential public facilities. Essential public facilities can be publicly or privately owned, and include existing and future facilities. Local Comprehensive Plans must identify the process for siting these facilities. Cities and counties cannot use their Comprehensive Plans to preclude the siting of these facilities though they can require mitigations of adverse impacts. Plans must consider the process for siting, expansion, or modification of essential public facilities.

Express Toll Lane | ETL

Express Toll Lanes are dedicated high-occupancy vehicle lanes that allow single-occupancy vehicles to use those lanes for a fee, or toll. Toll rates adjust based on traffic conditions. The primary goals of ETL are to provide a choice to drivers when they need it, provide a faster and more predictable trip, and to generate revenue for future improvements. Express Toll Lanes are a congestion pricing mechanism intended to improve overall highway system performance and increase person and freight throughput.

First-and-Last Mile Connections

First and last mile connections, also commonly referred to as last mile connections, refer to the first and last segments of a longer trip. Typically applied to public transit and freight, it refers to the ways that people or goods get to the primary mode of travel from their starting point and then, how they get from the primary mode of travel to their destination at the end of the trip. The term “mile” is not a literal definition of distance but implies a short trip segment. Sometimes referred to as “last mile connection” or “first mile-last mile service”. A wide and growing array of services, technologies, and other strategies are being deployed that address this part of the trip for both passenger travel and within the supply chain.

Growth Management Act | GMA

The Growth Management Act is a Washington state law first passed in 1990 requiring state and local governments to manage Washington’s growth by identifying and protecting critical areas and natural resource lands, designating urban growth areas, preparing comprehensive plans, and implementing them through capital investments and development regulations. This approach to growth management is unique to Washington. The GMA was adopted because the Washington State Legislature found that uncoordinated and unplanned growth posed a threat to the environment, sustainable economic development and the quality of life in Washington  Instead of centralizing planning and decision- making at the state level, GMA focuses on local control within a broad and coordinated framework of state goals. Within that framework, local governments have many choices regarding the specific content of comprehensive plans and implementing development regulations. The GMA establishes the primacy of the local Comprehensive Plan. The Comp Plan is the centerpiece of local planning and articulates a series of goals, objectives, policies, actions, and standards that are intended to guide day-to-day decisions by local and state agencies. A transportation element is a required component of the Comp Plan, and establishes Level of Service standards coordinated with local land use plans. The transportation element must be consistent with the Regional Transportation Plan which in turn must be consistent with local land use plans.

High Occupancy Vehicle | HOV

High Occupancy Vehicles are those carrying more than one person. In Washington, two or more people qualify as an HOV. In some other places HOV is defined as three or more people. HOV include vanpools and transit, as well as cars. HOV lanes are highway or street lanes restricted to use by vehicles with two or more people.

Highways of Statewide Significance | HSS

Highways of Statewide Significance are interstate highways and other principal arterials that connect major communities in Washington. The designation helps assist with the allocation and direction of funding.

Housing Affordability

Housing affordability is the relationship between housing costs and household income. Housing affordability can be measured for rented and owned housing. Once a focus primarily for very-low and low income households, it is increasingly a focus for middle income households in high growth areas where housing demand is outpacing supply, often in association with a large concentration of high-paying jobs. Traditionally, housing affordability is a housing cost that does not exceed 30 percent of a household’s gross income  Increasingly, though, transportation costs are included in this equation since an “affordable home” that requires a long, expensive commute is actually not affordable. “Housing + transportation” affordability is a combined cost that does not exceed 45 percent of a household’s gross income. Many factors influence housing affordability, including basic supply and demand of housing types and proximity to jobs, incomes, travel choices, and consumer preferences. Lack of housing affordability is associated with increasingly long commutes from communities with affordable housing to communities with a concentration of high paying jobs. People do not typically make long commutes for low-wage jobs.


Intermodal is the use of two or more modes of freight, such as truck and rail, to transport goods from shipper to receiver. The intermodal process usually begins with a container being moved by a truck to a railcar or ship, then back to a truck to complete the process.

Level of Service | LOS

Level of Service is a qualitative description of transportation system performance, reflecting agreed upon expectations about acceptable levels of performance. Historically, LOS was measured in terms of the number of vehicles using a system compared to the maximum volumes that system was designed to carry during a specific time period such as an hour, resulting in vehicle-based congestion measures usually for a one-hour peak period. Increasingly it is being redefined to better reflect overall community, regional, and statewide expectations about how the whole system performs, and its relationship to land use patterns. This may include all modes of travel, focus more on passenger or freight throughput than just vehicles, or emphasize reliability and predictability. This is especially important in highly urban corridors where maximizing system efficiency is critical. The Growth Management Act requires local agencies to adopt LOS standards in their Comprehensive Plans, monitor system performance, and use concurrency to ensure future growth does not diminish adopted LOS standards. It also requires that RTPOs establish LOS for regionally-significant facilities in collaboration with WSDOT on state facilities, and that local LOS be consistent with regional LOS  LOS standards for Highways of Statewide Significance are established by WSDOT. GMA provides great latitude in defining LOS, recognizing that it necessarily must reflect local conditions. A one-size-fits-all approach is not prescribed. Multimodal LOS is sometimes used to explicitly clarify that level of service includes other modes of travel in addition to the single-occupancy vehicle in describing system performance though any LOS standard can be multimodal.

Lifeline Route

Lifeline Routes are those priority multimodal transportation routes and facilities that will be most essential for emergency response after a major seismic event and which warrant hardening, retrofit, and mitigations to ensure their usefulness for this purpose. Washington’s lifeline routes include I-5 from McChord Air Force Base in Pierce County to Paine Field in Everett, I-405, and I-90 from I-5 to the Grant County International Airport in Moses Lake.

Metropolitan Planning Organization | MPO

A Metropolitan Planning Organization is a federally mandated and federally funded transportation policy-making organization designated by the Governor to administer federal planning requirements in urban areas with a population on 50,000 or more people. It is made up of representatives from local government and governmental transportation authorities. MPOs must comply with federal transportation requirements, and are authorized to award federal funds to projects in their region that help achieve adopted visions and goals. Duties include updating a 20-year regional or metropolitan transportation plan, a regional transportation improvement program (RTIP), and a unified planning work program (UPWP). Washington has twelve MPOs. State law requires MPOs to be the lead agency for Regional Transportation Planning Organizations where their boundaries overlap. Federal MPO requirements can be found in 23 CFR Part 450.

Mixed-use Development

Mixed-use development is a type of urban development that blends residential, commercial, cultural, institutional, or entertainment uses, physically and functionally integrating those uses in ways that provide pedestrian connections. The intent of this type of development is to create opportunities to live, work, shop, and recreate in close proximity to each other. This in turn makes walking, biking, and transit viable alternatives to driving for all trip purposes. It also lowers the per capita cost of providing other government services like water and police, reduces per capita environmental impacts and energy consumption, and supports other community objectives related to vitality and social opportunity. A surge of interest in mixed-use development across the country has characterized the real estate market since the Great Recession ended and corresponds to growing consumer demand for more walkable, car-lite lifestyle options.


Mobility refers to the movement of people and goods, regardless of travel mode. The purpose of mobility is typically not movement or travel itself, but getting access to a desired product or service or activity. In this way, mobility is a means to an end; the end is access.

Mobility as a Service | MaaS

Mobility as a Service is defined as shared-use multimodal mobility. This mobility is enabled by combining transportation services from public and private transportation providers through a unified smartphone app that creates and manages the trip, which users can pay for with a single account. MaaS represents a shift away from personally-owned modes of transportation and is increasingly transforming the business models of traditional transportation sectors like vehicle manufacturers and car rental businesses.

Multimodal Transportation

Multimodal transportation is two or more modes of travel to make a trip. A multimodal transportation system provides infrastructure and services that support more than just driving by car, such as transit, biking, walking, ferries, or newer modes of travel such as ride-hailing services.

Practical Solutions

Practical Solutions is an approach towards project planning and design that uses performance-based, data-driven decision making and early community involvement to guide the development and delivery of transportation investments. The intent is to increase the focus on system performance and enable more flexible and sustainable transportation investment decisions.

Regional Transportation Plan | RTP

A Regional Transportation Plan is a 20+ year blueprint for a region’s transportation system. They are developed by RTPOs and MPOs in accordance with state and federal laws, respectively, in coordination with adopted land use plans, and are updated on a regular basis. They describe regional growth and future transportation conditions, agreed upon Level of Service standards, transportation goals and policies, and recommendations which can range from specific projects and funding priorities to regional work program activities. Regional Transportation Plans for RTPOs must be consistent with the six legislative transportation goals at the center of the Commission’s statewide strategic policy plan, WTP 2040 and Beyond.

Regional Transportation Planning Organization | RTPO

A Regional Transportation Planning Organization is a voluntary association of local governments and other transportation stakeholders within a county or contiguous counties  RTPOs were established in Washington State in 1990 in association with Growth Management Act legislation. RTPO requirements can be found in RCW 47.80 and Chapter 468.86 WAC.

Resilient Washington

Resilient Washington is a state initiative to develop a framework and implementation strategies that will reduce the impact on life and property associated with a major earthquake, enable rapid response and recovery, and ensure the expedient restoration of services and livelihoods.

Road Usage Charge | RUC

A Road Usage Charge is a transportation fee based on vehicle miles traveled, where system users pay for use of the roadway based on distance traveled. The Transportation Commission is conducting a RUC pilot study in 2018 to evaluate the effectiveness of such a system and its impacts across the state on different types of system users.

Target Zero | TZ

Target Zero is the name of Washington’s Strategic Highway Safety Plan. It is based on the premise that no traffic fatality is acceptable, and it establishes as a goal the elimination of fatality and serious injury crashes by 2030. It emphasizes the “4 E’s” of transportation safety – engineering, education, enforcement, and emergency response. Target Zero is developed and maintained by the Washington Traffic Safety Commission.

Transportation Benefit District | TBD

A Transportation Benefit District is a quasi-municipal corporation and taxing district created for the sole purpose of acquiring, constructing, improving, providing, and funding transportation improvements within the district. A TBD can raise revenue for transportation projects through a vehicle license fee of $20 - $40, or a voter-approved .02 percent retail sales tax. Revenue may be used for improvements ranging from roads and transit service to sidewalks and transportation demand management activities. Construction, maintenance, and operation costs are eligible.

Transportation Network Company | TNC

A Transportation Network Company, sometimes referred to as a mobility service provider, is an organization that pairs passengers via websites and mobile apps with drivers who provide such services. TNCs are examples of the emerging sharing economy and shared mobility. Well-known examples of TNCs include Uber and Lyft, though many traditional companies like car manufacturers and software companies are also forming TNCs. This is a relatively new and rapidly evolving element of the transportation system, one that local and state agencies are still working to understand and incorporate seamlessly into a multimodal system that provides equitable access to social and economic opportunities.

Transportation Systems Management and Operations | TSMO

Transportation Systems Management and Operations refers to the practice of using multimodal transportation strategies, technologies, and pricing mechanisms to maximize the efficiency, safety, and utility of the existing transportation network. While it has application in any situation, it is particularly important in areas where roads and highways are largely built out or where transportation funding to increase capacity is limited. It includes such things as traveler information, ramp metering, incident management, traffic management centers, access management, travel demand managements, tolling and congestion pricing, among many other strategies to increase overall system operating efficiency and performance.

Travel Demand Management | TDM

Travel Demand Management encompasses a suite of tools that modify peoples’ travel behavior to better manage system capacity and improve operating efficiency. Examples of TDM tools range from “incentive” type programs like employer-subsidized bus passes, compressed work weeks, and telework options, to “market measures” like employee-paid parking and variable-rate toll roads with rates based on time-of-day travel. The State’s Commute Trip Reduction program is a TDM element. Even measures like effective land use planning fall under the realm of TDM, since the way a community is built – and the kind of travel options it provides – will influence individual travel behavior.

Urban Growth Area | UGA

An Urban Growth Area is a regional boundary established to designate where urban-style development exists and will occur in the future. Areas outside of a UGA boundary is intended to remain rural. A UGA boundary typically includes a city or town as well as the unincorporated area around it that will accommodate urban growth in the future, even though it may not be urban today.

Washington State Department of Transportation | WSDOT

The Washington State Department of Transportation is the owner-operator of the state’s transportation system. WSDOT is responsible for building, maintaining, and operating the state highway system and ferry system. WSDOT also works in partnership with others to maintain and improve local roads, railroads, and airports, as well as to support alternatives to driving, such as public transportation, bicycles, and pedestrian programs. WSDOT also conducts multimodal planning and manages the statewide RTPO and tribal transportation planning program.

Washington State Transportation Commission | WSTC

The Washington State Transportation Commission is a seven member body of citizens appointed by the Governor for six-year terms, and includes the WSDOT Secretary and a representative from the Governor’s Office as ex officio members. As a public forum for transportation policy development, the Commission develops and maintains a 20-year strategic statewide policy plan that addresses local, regional, and statewide needs, and coordinates state transportation policy with local and regional transportation and land use plans. It is designated as the State Tolling Authority and establishes all state and bridge tolls and sets fares for Washington State ferries. It conducts other tasks assigned by the legislature, including in 2018 a Road Usage Charge Pilot Program, and an Autonomous Vehicle Work Group.

WSDOT Strategic & Modal Plans:

WSDOT Strategic & Modal Plans:

State Ferries Plan

2040 long-range plan for the State's ferry system

Travel Washington Intercity Bus Plan Update

An update to 2007 studies that will be used to evaluate and possibly refine existing Travel Washington services

Aviation System Plan

2034 long-range plan for the State's aviation system

Freight System Plan

Technical update to the 2035 long-range freight plan completed in 2014

Grain Train Strategic Plan

10-year strategic plan supporting the Washington Grain Train program

Public Transportation Plan

20-year strategic plan for public transportation systems statewide

Target Zero Strategic Highway Safety Plan

Strategic plan working to eliminate traffic fatalities by 2030

Passenger & Freight Rail Plan

Current rail plan. An update is underway with completion anticipated in 2019

Statewide Human Services Transportation Plan

Strategic framework for addressing existing and future human services transportation needs

2008* / 2019
Bicycle Roadways & Pedestrian Walkways Plan

Current non-motorized plan. An update is underway with completion anticipated in 2019.

Highway System Plan

Highway component of the State's multimodal transportation plan