Climate Change, Child Health & Neighborhood Safety

What is the connection between climate change, child health and neighborhood safety?

All three of these issues are affected by traffic congestion.

Reducing traffic congestion decreases emissions of climate-changing greenhouse gases along with other air pollutants impairing child health.  As congestion increases, more and more drivers use local roads to bypass backups which is part of the reason why our neighborhood streets have some of the highest pedestrian-cyclist injury rates of all roads.

Reducing the number of people driving alone is the key to resolving all three impacts.  Following are some of the measures essential to providing all of us with better alternatives to Single Occupant Vehicle travel:

  • Make bus and other transit services more convenient and reliable,
  • Assist employers in making it easier for their employees to form car-pools or work from home, and
  • Discourage the use of neighborhood streets to bypass congestion through the use of speed humps and other traffic calming measures.

How does traffic congestion affect climate change?

The two graphs below are from the Miami-Dade County Climate Change Action Plan. These graphs show that transportation is the second largest source of the greenhouse gas (GHG) carbon dioxide in Miami-Dade County and that passenger cars account for 68% of these emissions.

This third graph shows that driving alone (Single Occupant Vehicle travel) generates far greater amounts of GHG emissions compared to carpools, buses, and rail.

How does traffic congestion affect child health?

The U.S. Department of Health & Human Services Traffic-Related Air Pollution and Children’s Health webpage begins:

“Traffic-related air pollutants are emitted by cars, trucks, buses, and “non-road” equipment (e.g., recreational vehicles or lawn equipment) from the burning of fossil fuels. Traffic-related air pollution contributes significantly to outdoor air pollution, especially in urban settings.  Children are especially sensitive to air pollution, and there is increasing evidence that exposure to traffic-related air pollution (TRAP) may impact pregnancy outcomes and child development.”

According to the USEPA, transportation sources account for more than half of nitrogen oxides (NOx).  These NOx air pollutants can cause lung irritation and make us more susceptible to respiratory diseases such as pnuemonia and influenza.   Just as driving alone (SOV) maximizes greenhouse gas emissions, the same is true for NOx and the other air pollutants threatening our health.  And congestion maximizes air pollutant emissions.

How does traffic congestion affect neighborhood safety?

The following table shows that of all road types, local streets have the highest fatality rate.  These local roads are mostly the neighborhood streets we live on.

Once congestion causes main road speed to drop to half the non-rush-hour speed drivers begin seeking bypass routes.  Frequently the bypass route is a neighborhood street.  This cut-thru traffic tends operate at a higher speed.  As shown in the following graphic, as speed increases so does the likelihood of an accident and serious injury.

The net result is that main road congestion increases both the volume and speed of traffic on our neighborhood streets which accounts for why they are the most dangerous of all our roads.

Why more roads are not the traffic congestion solution?

In the past, transportation planners believed that building new roads and adding lanes to existing thoroughfares was the way to keep traffic moving.  While this approach worked for a long time, it is no longer enough.  The reason is a phenomenon known as Induced Demand

Here’s how it works. 

Once a new road reduces congestion, those who used to avoid rush-hour travel to avoid excessive delay begin driving again.  Thus while a new road may reduce congestion for a while, it soon comes back to the same level of delay.

How does the future look for Miami-Dade traffic congestion?

The map below is from the Miami-Dade County Comprehensive Development Master Plan (CDMP).   The color coding shows the degree of traffic congestion on roads throughout the County come 2030.  The pink-purple and red roads will be severely congested.  Emissions of climate-changing GHGs and other health damaging air pollutants will be at a maximum on these roads.  Furthermore, the neighborhood streets paralleling these congested roads will experience volumes of cut-thru traffic and the attendant higher pedestrian-cyclist injury rates.

Reducing future congestion to minimize climate change, protect child health, and make our neighborhood streets safer

The Miami-Dade  Climate Change Action Plan outlines a number of Smart Transportation options which would reduce emissions by encouraging greater use of transit, carpooling and other alternatives to driving alone. A more complete list of congestion management options are presented in Table 6-19, of the Miami-Dade 2040 Long Range Transportation Plan, which appears below.

Combined, the Smart Transportation and Congestion Management options would achieve four goals:

  • reduce main road congestion, thereby
  • reducing GHG and child-health threatening pollutant emissions,
  • improve transit accessibility, and
  • collectively make our neighborhood streets safer by curbing cut-thru traffic seeking to bypass congestion.

Making neighborhood streets safer increases public support for Smart Transportation and Congestion Management options

One of the more ironic aspects of this whole dilemma is that cut-thru traffic on neighborhood streets decreases congestion slightly and thereby decreases public support for the best solutions.  In exchange for this minimal benefit we suffer increased risk to our children and others who walk, run or bike along our neighborhood streets.  Traffic calming measures like raised pedestrian crossings pitured below reduce cut-thru traffic while slowing speed.  However, the minimal traffic congestion relief provided by cut-thru is part of the reason why more Miami-Dade neighborhood streets do not benefit from calming measures.

Support efforts by the Miami-Dade Mayor and County Commissioners to reduce climate change, protect child health, and make neighborhood street safer

Please take a moment to assess your neighborhood with regard to measures that protect the climate, child health and pedestrian-cyclist safety by taking the survey at:

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