As
discussed in [addressee and further motivation for document is omitted], transportation
and vehicles account for roughly one-third of greenhouse gas emissions.[1] The premise of this writing is to put forth
the argument that better infrastructure - including more adequately designed
and modern roadways to reduce vehicular traffic congestion - would help to
decrease carbon emissions and pollutants from transportation sources and
thereby reduce carbon footprints and any subsequent accumulation of Green House
Gases (GHGs) in the atmosphere as a result.
Most
of the nation’s interstates and highways were designed in excess of five
decades ago when the population of most urban areas was merely a fraction of
what the respective populations are today – increased population which is
exacerbated by the number of cars on the roads to service the larger populace.[2] Such a proposed paradigm of better designed
roadways also creates further positive externalities including less pollution
as well as more jobs to build and maintain roadways – though there is some
debate as to which transportation projects build more jobs, i.e.: public
transportation v. public roadways and jobs creation.[3]
While
this sensitive subject and corresponding argument is vastly more entailed than
can be completely addressed by this short writing, this note is to nevertheless
address the framework for such an argument. Regardless, any Climate Action Plan (“CAP”) that
does not allow for the increased capacity of roadways to handle the
ever-increasing in-flow of residents who will likely own cars seems off-base
and lacking in foresight. Lack of how to
properly mitigate any greenhouse gas difficulties that the region currently and
continues to face into the future seems unrealistic without significantly
reducing traffic congestion – especially concerning freeway congestion.[4]
The
amount of pollution created by an internal combustion engine vehicle correlates
to the amount of fuel a vehicle’s engine burns.[5] Driving less therefore would decrease
pollution from vehicular sources by running the vehicle’s engine less.[6] Of course, driving less would seem to
correspond to spending less time while driving in one’s vehicle as well.
As
a common sense example of unnecessary pollution from vehicles, automobiles tend
to burn much more fuel when traversing any given 30 miles in the timespan of an
hour and a half (i.e.: at 10 miles per hour, “mph”) due to traffic congestion
on the scale of “city traffic” (e.g..: repeatedly stopping and starting) as
opposed the amount of fuel burned when traveling the same 30 miles on the
freeway at normal uncongested freeway speeds which would take approximately 30
minutes (say, at 60 mph).[7] In other words, the matter seems one of
common sense that better fuel efficiency ultimately pollutes less and better
fuel economy is generally not available to the fuel-burning engines of vehicles
that are sitting idle in traffic and therefore going no miles for the gallons
of gas the vehicle burns while sitting in the traffic congestion – as often
seems typical for much of the nation’s highways during rush-hours.
The
lesser fuel economies/efficiencies from vehicular sources include vehicles
inching-along in bumper-to-bumper traffic as opposed to a vehicle that is
getting more miles per gallon by moving at unfettered freeway speeds.[8] From a numbers point of view and considering
all external factors to otherwise be equal, while a vehicle could burn twice
the amount of fuel for a given timespan at 70 mph as opposed to idling in
bumper-to-bumper traffic for the same time period, if traveling at 70 mph takes
one third the amount of time compared to traveling in bumper-to-bumper traffic,
ultimately the freeway travel speed will consume less fuel and therefore likely
pollute less because the vehicle spends significantly less time on the roadway
and also maintains significantly increased fuel efficiencies as well.[9] The realities of less pollutants from
vehicles traveling at freeway speeds are further illuminated when viewed in light
of the realities of modern vehicle emission controls systems[10] and the torturous time-consuming
crawl of most highway traffic congestion situations.[11]
For
instance, while a car arguably may release more GHGs when it is motoring at 70
miles/hour (level-ground cruising at 70 “mph,” typically at 2000 rpm) as
opposed to when it is idling and sitting still (0 mph, yet 1000 rpm), when a
vehicle is idling or sitting motionless in one place then the amount of GHGs
emitted are concentrated or more dense per area polluted than compared to the
vehicle that is motoring by at a speed of 70 mph.[12] However, even such an assumption/comparison
is unlikely to be valid given modern emissions controls as some internal
combustion engine by-products/pollutants decrease at higher speeds.[13] Furthermore, those GHGs that are released
during a non-moving idling period are emissions/pollutants that essentially
resulted in no productive work either (as work is physically defined as a force
moving/working over a distance).[14] And again, Barth et.al.
displayed that cruising at constant normal travel speeds tends to burn less
fuel and pollutes less – with freeway congestion being the most inefficient
fuel consumption and the larger comparative source of pollutants, especially in
light of the stop and start driving realities of traffic congestion.[15]
As
this writing has attempted to display, traffic congestion is likely a major
contributing factor to vehicle emissions and pollutants. And as anyone who has ever undergone the
misery of having to travel 30 miles or more in bumper-to-bumper freeway/highway
traffic can attest, the roadways of our nation are seriously under-designed and
outdated for the volume of traffic to which the roads support in most of the
nation’s urban regions. The literature
seems to extend ad nauseam concerning the increased volume and density of pollutants
from vehicles in traffic congestion – as discussed herein and above. For any government entity to currently gamble
on the adequacy of future plans to reduce vehicular traffic and to concurrently
ignore the inadequacy of nation’s highways and roadways, that government entity
seems more than short-sighted. This writer believes that our nation would be
well-served to start building modern and adequate roadways to support the level
of traffic to which those roads are modernly subjected (and allow room for continued
expansion as well). To rely on the outdated
designs and traffic estimates of 1960 – which is when most of the nation’s
interstates and highways were designed and built, seems misguided.
Adam Trotter P.E.
May 2017.
Adam Trotter P.E.
May 2017.
[1] How Does the Release of Car Exhaust Fumes
Cause Global Warming?; by J.T. Barett, SEATTLE PI, located at: http://education.seattlepi.com/release-car-exhaust-fumes-cause-global-warming-3682.html. Also see:
Road Transportation Emerges as Key
Driver of Warming, Feb. 18, 2010, NATIONAL AERONAUTICS AND SPACE
ADMINISTRATION, Goddard Institute for Space Studies, located at: https://www.giss.nasa.gov/research/news/20100218a/.
[2]
For example, San Diego County’s population has tripled from 1,000,000 to over
3,000,000 since 1960. From: Population.us, located at: http://population.us/county/ca/san-diego-county/#2. For sake of illumination, the Greater Los
Angeles population is currently approaching 19,000,000, also three times the
population in 1960, from: Population Growth
in California, located at: http://cgge.aag.org/PopulationandNaturalResources1e/CS_US_July09/CS_US_July094.html. See also:
Density, Car Ownership, and What It Means for the
Future of Los Angeles, By Damien Newton,
Dec 13, 2010, STREETSBLOGLA.ORG, located at: http://la.streetsblog.org/2010/12/13/density-car-ownership-and-what-it-means-for-the-future-of-los-angeles/.
[3]
For example: “According to data sent by
the states to Congress, the states that created the most jobs were the ones
that invested in public transportation projects and projects that maintained
and repaired existing roads and bridges.”, New report reveals smart
transportation spending creates jobs, grows the economy, SMART GROWTH AMERICA, February
4, 2011, located at: https://smartgrowthamerica.org/new-report-reveals-smart-transportation-spending-creates-jobs-grows-the-economy/.
[4]
For instance, see: San
Diego Climate Action Plan (CAP), which only superficially, at best, addresses vehicular
freeway congestion. Located at: https://www.sandiego.gov/sites/default/files/final_july_2016_cap.pdf
[5] “Fuel Economy And Air Pollution. The amount of co2 emitted by a vehicle is
essentially proportional to the amount of fuel burned.”, Global Warming. GREENCARS.ORG,
located at: http://www.greenercars.org/automobiles-environment/global-warming.
[6] How much air pollution comes from cars?,
by Linda C. Brinson, HOW STUFF WORKS,COM, located at: http://auto.howstuffworks.com/air-pollution-from-cars.htm.
[7]“A
key element in assessing the EPA rating for a vehicle's average fuel economy
(EPA combined) is the split between highway and city driving. Almost all cars
and trucks deliver better fuel economy while cruising at 55 mph on the open
highway than they do while stopping and starting at low speed on city streets.”;
Here's Why Real-World MPG Doesn't Match
EPA Ratings. Why Your Car Could Have an
MPG Gap, by John O'Dell, EDMUNDS .COM, Sept. 2012, located at: https://www.edmunds.com/fuel-economy/heres-why-real-world-mpg-doesnt-match-epa-ratings.html.
[8] “This
is because carbon dioxide emissions are directly related to the amount of fuel
consumed.”, Gasoline Vehicles. Learn More About the New Label. U.S. DEPT.OF
ENERGY, located at: https://www.fueleconomy.gov/feg/label/learn-more-gasoline-label.shtml.
[9] See: “Car makers can meet these targets
through improved fuel efficiency and an alteration to their mix of models using
only current technology.” Green Peace
Worldwide, located at: http://www.greenpeace.org/international/en/campaigns/climate-change/cars/questions-answers/.
Also see, for instance, Footnote 7, supra.
[10]
See: Emission
Control Devices, located at: http://www.mopar.ca/en/partsandaccessories/emission-control-devices.html. Also see, Footnotes 7 and 8, supra.
[11]
“As mean speed increases, the travel time on a link decreases even though the
emission rate tends to increase. The
resulting estimates of total emissions for the example case study are shown in
Figure 5. These results indicate that
the total emissions tend to decrease as mean speed increases. Of course, an increase in mean speed is
associated with a decrease in travel time.
The speed profiles for higher average link speeds typically have more
constant cruising speed, whereas the speed profiles for lower average link
speeds may have more deceleration and acceleration events. The latter, in particular, can lead to higher
total emissions. The total emissions on
one trip depend on both on the travel time and the average emission rates, but
are influenced by micro-scale events.
For example, driving situations, whether caused by driver behavior or
traffic flow problems, that lead to increased frequency of acceleration events
can lead to higher average emission rates.”, Speed and Facility-Specific Emission Estimates for
On-Road Light-Duty Vehicles based on Real-World Speed Profiles. By H.Christopher
Frey PhD., et.al. North Carolina State Univ., 2006.
[12] Driving for Fuel Economy, by Larry
Webster CAR and DRIVER Magazine; August
2006, located at: http://www.caranddriver.com/columns/driving-for-fuel-economy. See also: Vehicle
Emissions in Congestion: Comparison of Work Zone, Rush Hour And Free-Flow
Conditions, by Kai Zhang, et.al., ATMOSPHERIC ENVIRONMENT 45 (2011) 1929 –
1939, located at: https://sph.uth.edu/kaizhang/files/2014/02/Zhang-2011-AE.pdf. See also:
No idle matter,
TRAFFICTECHNOLOGYTODAY.COM, located at: http://www.traffictechnologytoday.com/features.php?BlogID=718.
[13] “Policy
makers have placed less attention on reducing CO2 emissions by reducing traffic
congestion. As traffic congestion increases, so too do fuel consumption and CO2
emissions. … If congestion reduces the average vehicle speed below 45 mph (for
a freeway scenario), CO2 emissions increase. Vehicles spend more time on the
road, which results in higher CO2 emissions. Therefore, in this scenario,
congestion mitigation programs will directly reduce CO2 emissions.”; Estimating Emissions and Fuel Consumption
for Different Levels of Freeway Congestion, M.Barth, et.al., TRANSPORTATION
RESEARCH RECORD 1664, Paper No. 99-1339; located at: http://cmscert.engr.ucr.edu/cmem/docs/TRR1999-Different-Congestion.pdf. See also: Traffic
Congestion and Greenhouse Gases, by M. Barth, et.al., ACCESS,
[14] “Work
is done when a force that is applied to an object moves that object. The work
is calculated by multiplying the force by the amount of movement of an object
(W = F * d). A force of 10 newtons, that moves an object 3 meters, does 30 n-m
of work.”, PHYSICS4KIDS.COM, located at: http://www.physics4kids.com/files/motion_work.html.
[15] Estimating Emissions and Fuel Consumption
for Different Levels of Freeway Congestion, M.Barth, et.al., TRANSPORTATION
RESEARCH RECORD 1664, Paper No. 99-1339; located at: http://cmscert.engr.ucr.edu/cmem/docs/TRR1999-Different-Congestion.pdf.
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