We can’t see it. We can’t smell it. But air quality can have a significant impact on the transportation planning process. This issue will try to provide readers with a basic understanding of air quality.

What types of pollution affect transportation planning for the Metropolitan Planning Organization (MPO)?

The following pollutants are of primary concern to Transportation Planning:

• Carbon Monoxide (CO): A colorless, odorless, tasteless gas formed in large part by incomplete combustion of fuel. Human activities (i.e., transportation or industrial processes) are largely the source for Carbon Monoxide production.
• Volatile Organic Compounds (VOCs): A byproduct of fossil fuel combustion, which, when combined with Nitrogen Oxides and exposed to heat from sunlight, produces ozone.
• Nitrogen Oxides (NOx): A byproduct of fossil fuel combustion, which when combined with Volatile Organic Compounds and heat from sunlight, produces ozone.
• Ozone (O3): A colorless gas with a sweet odor. Ozone is not a direct emission from transportation sources. It is a secondary pollutant formed when VOCs and NOx combine in the presence of sunlight. Ozone is associated with smog or haze conditions. Although the ozone in the upper atmosphere protects us from harmful ultraviolet rays, ground-level ozone produces an unhealthy environment in which to live.

What is Conformity?

Conformity is the process of assessing the compliance of any transportation plan, program or project with air quality implementation plans. It is a way to ensure that Federal funding and approval are given to those transportation plans that are consistent with air quality goals. According to the Clean Air Act of 1991, transportation plans cannot:

• Create new violations of the Federal air quality standards.
• Increase the frequency or severity of existing violation of the standards.
• Delay attainment of standards.

Because driving is so closely linked to air pollution, federal law requires the High Point Urban Area’s Long Range Transportation Plan to support the goals of North Carolina’s air quality plans. Without this “conformity”, the urban area risks losing its federal transportation funds.

How does Conformity affect the MPO?

Under the Clean Air Act, States and MPOs must demonstrate, through the conformity process, that the transportation investments, strategies and programs they choose, taken as a whole, have air quality impacts consistent with those contained in the State Implementation Plans (SIP) for achieving the National Ambient Air Quality Standards.

If a transportation plan, program, or project does not meet conformity requirements, transportation officials have the following options:

• Modify the plan, program, or project to offset the expected emissions.
• Work with the appropriate State agency to modify the SIP to offset the plan, program, or project emissions.

If the above is not accomplished, and if a conformity determination cannot be made within certain time frames after amending the SIP, or if three years passes since the last conformity determination, a conformity lapse occurs and no new projects may advance until a new determination for the plan and Transportation Improvement Program (TIP) can be made.

What triggers a Conformity Analysis?

The following actions initiate the need for a Conformity Analysis:

• Establishment or Revision of the Emissions Budget. The State or Federal Government determines this need.
• Long Range Transportation Plan adoption or amendment
• Establishment or revision of Traffic Control Measures.
• For maintenance areas, a Conformity Analysis is required every three (3) years.

In short, a new analysis is required whenever the transportation plan adds a project, deletes a project, significantly delays or accelerates a project, or changes the project scope.

What variables are considered when determining conformity?

Emission rate models (often referred to as the Mobile models) are used to estimate emissions for the area, taking into consideration factors such as the mix of vehicle types, temperature, etc. These rates are then applied to the vehicle miles traveled and speed estimates from the travel demand model to calculate motor vehicle emissions rates.

How do emission levels determine the classification of urban areas in reference to air quality?

Based on the air quality monitoring results, the area can be classified into the following categories.

• Attainment Area: An area considered to have air quality that meets or exceeds the United States Environmental Protection Agency’s health standards used in the Clean Air Act. An area may be an attainment area for one pollutant and a nonattainment area for others.
• Nonattainment Area: Any geographic region of the United States that has been designated as nonattainment for any pollutant for which a National Ambient Air Quality Standard (NAAQS) exists. The nonattainment designation identifies the area as an area where pollution levels have exceeded those standards prescribed by the EPA. The designation requires that those areas designated as such implement strategies to improve air quality or risk losing funding.
• Maintenance Area: Any geographic region of the United States previously designated nonattainment pursuant to the Clean Air Act amendments of 1990 and subsequently redesignated to attainment subject to requirement to develop a maintenance plan.

Guilford and Davidson Counties were originally declared nonattainment for ozone (O3) on January 6, 1992. At that time, Guilford and Davidson Counties were classified as moderate nonattainment. On November 8, 1993, both counties were redesignated to maintenance for ozone.

What options are available to improve air quality?

These options are often referred to as Transportation Control Measures (TCMs). Funds are available from the State and Federal government to aid in the implementation of these strategies. Below is a list of traffic control measures and cost effective transportation strategies.

• Bike / Pedestrian Improvements
• Reformulated Gasoline
• Inspection and Maintenance Programs
• Ridesharing
• Parking Pricing
• Signal Timing
• High Occupancy Vehicle (HOV) Lanes
• Park / Ride Lots
• Transit Improvement

Why are these options necessary?

Each of today’s cars produces 60 to 80 percent less pollution than cars in the 1960s. However, more people are making more vehicle trips. In 1970, Americans traveled 1 trillion miles in motor vehicles, and that was projected to increase to 4 trillion miles per year by the year 2000. Transportation options are the most effective means of reducing vehicle miles traveled, congestion, and pollution.

Why does air quality affect transportation?

Construction of wider roads reduces congestion temporarily. Once congestion is reduced with additional lanes, the roadway becomes more attractive to motorists until saturation is again reached. The addition of a project can also increase congestion on connecting roads. While congestion does contribute to pollution problems, it also serves as a means to deter added vehicle miles traveled. Thus, there is a need for transportation professionals to explore alternative forms of transportation.

Glossary

Emission Budget for motor vehicles: The total of all motor vehicle emissions identified in the State Implementation Plan (SIP) that an area can produce and still achieve the SIP’s purpose which is to demonstrate attainment of the air quality standard or in some cases, demonstrate maintenance of the standards.

Emissions Sources: Emissions are generally classified in one of three categories: stationary sources, area sources, and mobile sources.

• Stationary sources are relatively large, fixed sources of emissions such as power plants, chemical process industries, and petroleum refineries.
• Area sources are small, stationary and nontransportation sources that collectively contribute to air pollution (e.g., dry cleaners, bakeries, etc.)
• Mobile sources include on-road sources such as cars, trucks, and buses, and off-road sources such as trains, ships, boats, airplanes, lawnmowers, and construction equipment.

National Ambient Air Quality Standards (NAAQS): Federal Standards that set allowable concentrations and exposure limits for various pollutants. The EPA developed the standards in response to a requirement of the Clean Air Act.

Parking Pricing: Governments may implement many pricing approaches. They may:

• Impose or increase fees and surcharges for solo drivers or long term parkers in public parking facilities.
• Give price preference to car and vanpoolers.
• Tax the providers of parking, whether commercial operators of parking or all public and private entities providing parking .
• Impose parking pricing through regional regulations, for example air quality regulations or special legislation.
• Tie funding (especially state government) allocations for road improvements to requirements for local trip reduction plans incorporating parking pricing among other demand management strategies.

State Implementation Plan (SIP): State air quality plans required by the Clean Air Act for nonattainment and maintenance areas. The plans are prepared by state air quality agencies and include estimates of future air quality and control strategies to attain appropriate air quality standards.

Transportation Control Measures (TCM): Actions to adjust traffic patterns or reduce vehicle use to reduce air pollutant emissions. These may include HOV lanes, provision of bicycle facilities and sidewalks, ridesharing, telecommuting, etc. Such actions may be included in a SIP if needed to demonstrate attainment of the NAAQS.

Vehicle Miles Traveled (VMT): The sum of distances traveled by all motor vehicles in a specified region.