Glossary of Terms

Washington State's Revised Code (RCW) Chapter 46.92 defines an autonomous vehicle as a motor vehicle equipped with "autonomous technology" that enables it to operate without the active human control or monitoring for any duration of time, aligning with SAE International Levels 4 or 5 of driving automation, or the ability for sustained steering and lane departure. This definition excludes vehicles with only automated features like adaptive cruise control or blind spot detection, but includes systems that can work together to allow driving without human monitoring.

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).

The Commute Trip Reduction (CTR) Program is authorized by RCW 70.94.521-551 under Washington's Clean Air Act. CTR is an employer-based travel demand management program. 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.

The Growth Management Act (RCW 36.70A) 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 (RCW 36.70A.070(6)(b)) is required by 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 - 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.

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.

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.

In Washington state, environmental justice is primarily defined by the Healthy Environment for All (HEAL) Act, passed in 2021 and codified in RCW 70A.02. The law defines environmental justice as "the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income" and includes addressing disproportionate environmental health impacts in overburdened communities.

In Washington State, essential public facilities are primarily defined by RCW 36.70A.200 and WAC 365-196-550, which describe them as public facilities that are difficult to site and often include examples like correctional facilities, regional transportation facilities, state education facilities, and large in-patient facilities. The law requires counties and cities to establish processes for identifying and siting these difficult-to-site facilities, and local jurisdictions create their own comprehensive lists of essential public facilities.

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, 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.

The Growth Management Act (RCW 36.70A) 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.

In Washington state, high occupancy vehicles are defined in RCW 46.61.165, which allows the state and local authorities to reserve highways for exclusive or preferential use by public transit vehicles and private vehicles carrying a specified number of passengers. The specific number of occupants is determined by signs posted for the particular HOV lane.

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 is the relationship between housing costs and household income. Transportation costs also factor into housing affordability. 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 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 (RCW 363.70A) 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. RCW 47.06.140 defines the level of service standards for transportation facilities and services of statewide significance in Washington.

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.

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 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.

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 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 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.

In Washington state, RCW 47.80.030 defines Regional Transportation Plan (RTP) as a document created by a regional planning organization (RPO) that outlines a region's transportation needs and proposed solutions for the next 20 years. RTPs are required to be based on least cost planning, identify existing and planned transportation facilities and services, and include financial and level of service plans for regional transportation systems. This law establishes the framework for regional planning organizations (RPOs) to create and update these plans, ensuring coordination with local comprehensive plans under the Growth Management Act (RCW 36.70A).

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.

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 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. Target Zero is federally required and developed by the Washington Traffic Safety Commission in partnership with WSDOT.

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 $50 without voter approval, or with voter-approval a $100 vheicle license fee can be imposed. A TBD can also impose up to 0.3 percent sales and use tax with voter approval. 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. Washington state law defines Transportation Benefit District (TBD) in Chapter 36.73 RCW and RCW 35.21.225.

In Washington State, RCW 46.72B defines a Transportation Network Company (TNC) as an entity using a digital network to connect passengers with drivers who use personal vehicles to provide prearranged transportation. This state law specifies regulations for TNCs, including requirements for driver and vehicle certification, record retention, and zero-tolerance policies, while also preempting local regulations on certain aspects of TNC operation. Well-known examples of TNCs include Uber and Lyft, though many traditional companies like car manufacturers and software companies are also forming TNCs.

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 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.

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. RCW 36.70A.110 requires counties to designate UGAs where urban growth is encouraged and adequate urban services and facilities will be provided, while land outside these areas is reserved for non-urban uses.

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.

The Washington State Transportation Commission (WSTC) 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. WSTC provides a public forum for transportation policy development, developing and maintaining the 20-year strategic statewide transportation policy plan that addresses local, regional, and statewide needs, and coordinates state transportation policy with local and regional transportation and land use plans. WSTC is designated as the State Tolling Authority and establishes all state and bridge tolls and sets fares for Washington State ferries. WSTC also conducts special studies assigned by the legislature, including in 2018 a Road Usage Charge Pilot Program, and an Autonomous Vehicle Work Group.