Greenhouse Gas Emissions
According to the U.S. Environmental Protection Agency, in 2010 transportation contributed approximately 27 percent of total greenhouse gas emissions in the United States. Additionally, transportation accounted for 45 percent of the net increase in total greenhouse gas emissions in the United States from 1990-2010. Globally, as of 2008, China, the United States and the European Union were the top emitters of carbon dioxide (CO2) from fossil fuel combustion and some industrial processes.
Non-renewable fossil fuels, such as coal, petroleum (oil), and natural gas meet around 82 percent of U.S. total energy demand. According to the Institute for Energy Research, as of 2012, 95.5 percent of the United States’ transportation sector consumed fossil fuels. As consumption and demand for these resources increase, availability is rapidly declining. Reliance on fossil fuels from other countries creates vulnerabilities within U.S. energy security and can lead to extreme price fluctuations. While domestic hydraulic fracturing can lower the price of natural gas in the United States, the environmental challenges (such as the possibility for groundwater contamination) of this method are still somewhat unclear.
Alternative fuel vehicles are becoming more commonplace, for city departments and otherwise, as gas prices continue to rise. However, reliable access to renewable energy options to power current and future transportation demands continues to remain a challenge. For example, since fossil fuels still generate much of the power in the United States, electric cars would not actually be contributing to reducing emissions within this framework.
Across the country local governments are struggling to maintain and repair aging transportation infrastructure such as roadways, highways, and bridges. Cities that support multi-modal transportation options must often decide how to allocate financial resources to both ensuring the safety of existing transportation infrastructure while also supporting new options such as public transit, complete streets, and increased connectivity. Federal funding sources often have rigid parameters on the type of transportation projects the money can fund, which may limit or exclude multi-modal transportation options.
Regardless of how many or what types of multi-modal options a local government decides to invest in, one of the biggest challenges is being able to meet the demand by consumers at various times of the day. While public transit helps to alleviate peak level traffic on roads, transit agencies still face the challenge of ensuring that public transit infrastructure is flexible enough to accommodate various passenger loads throughout the day. Similarly, local governments often face the challenge of pricing transit options appropriately so that maintenance costs are covered while keeping fares affordable for users.
Although people are moving back to cities in high numbers, at a local and regional scale there is often a disparity between where residents can afford to live and where employment opportunities and various amenities are located. As a result, many residents experience long commutes in personal vehicles (contributing to traffic congestion and greenhouse gas emissions), or via public transit that may or may not be fully integrated into a multi-modal transportation network that provides convenient access to areas outside of the immediate downtown corridor. This spatial mismatch can be a significant challenge for local governments attempting to meet the travel demands of an increasingly socioeconomically diverse and multi-generational population.
Commuting costs are often a deterrent for residents who would typically use public transit options. In some cases, commuting by car is cheaper than using public transit. Additionally, if multi-modal systems are not fully integrated, traveling by public transit could take more time than driving. In 2012, the Center for Housing Policy and the Center for Neighborhood Technology found that for households earning 50 – 100 percent of the median income of their metropolitan area, 59 percent of income goes towards housing and transportation costs. Similarly, between 2006 and 2010, for the top 25 regions combined, 27 percent of income went towards transportation costs.
Human health is impacted by emissions, especially for the very young, elderly and those who already suffer from respiratory disease. While the federal Clean Air Act has been successful in reducing emissions from transportation and other sources, exposure to air pollution, as well as sedentary behavior encouraged by automobile travel, can exacerbate respiratory illness, anxiety, and produce indirect health effects such as obesity and heart disease.
Public Safety and Education
Cities that offer multiple modes of transportation for residents often face the challenge of ensuring that all road users are safe, comfortable and knowledgeable about the multi-modal transportation system. The first component is that bicycle and pedestrian networks may not be easily visually marked, increasing the rate of fatalities when sharing the road with automobiles. Additionally, a lack of knowledge about how to navigate the road with various types of users also has a large impact on safety.Although a popular term, the specific definition varies among states. Generally speaking, alternative fuel is any substance that can be used as fuel that is not petroleum based, i.e. gasoline, diesel, coal, propane, or kerosene. Alternative fuel is typically derived from BIOMASS material or natural gas. The term is also applied to petroleum-based fuels that have been mixed with some percentage of alternative fuel. Common types of alternative fuels include solar, vegetable oil, alcohol, hydrogen, compressed air, and electricity. Energy that comes from sources that are not depleted by use. Examples include energy from the sun, wind, and small (low-impact) hydropower, plus geothermal energy and wave and tidal systems.Greenhouse gases are a part of the Earth's atmosphere and are both naturally occurring and the result of human chemical processes. The most common greenhouse gases are carbon dioxide, water vapor, methane, nitrous oxide, ozone, and chlorofluourocarbons. These gases trap heat and thus contribute to the warming of the planet. See also CFCS and GREENHOUSE EFFECT.Fuel formed from geological processes acting on the remains of living organisms. Typically refers to oil, coal, natural gas or their by-products.The ability or potential of a physical body to do work. The most common forms of energy are heat, light, mechanical (moving parts), and electrical.