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Monday, June 29, 2020

VMT and GHG Emissions

Myths of "VMT-Mitigation"

Many Cultures have Myths of Fantastical Creatures
One such is "VMT-Mitigation"


California has mandated that cities use "Vehicle Miles Traveled" (VMT) instead of "Level of Service" (LOS) to measure environmental impacts of new development projects.  The idea is that if people drive less then there will be fewer pollutants and greenhouse gasses (GHG) emitted.

Sounds nice.  However, US Census data for last 15 years (2002-2017) shows this to be pure fantasy.  Despite more and more building near job centers in the SF Bay Area and Sunnyvale, data shows VMT has increased significantly whether measured by city, county, or 9-county area.

It's getting worse, in case you hadn't noticed.

The hypothesis "build more housing near work centers to lessen VMT" is shown to be counterfactual.

Normally, I wouldn't bother analyzing it because very few people will actually do what planners want.  VMT will continue its upward trend, and eventually electric vehicles will solve the GHG emissions issue.   However, the proposals include reduced parking because everyone will walk-bike-bus to work, and Sacramento policy makers apparently want to make freeway traffic worse.  This will not turn out well.
Vehicle Miles Traveled
1970 - 2020 Annualized

Another, more subtle, point is that if decision-makers actually think this VMT reduction idea works in reducing GHG emissions, they will be less inclined to support more significant measures that actually do work, such as requiring all new office construction to have "net-zero" GHG emissions.

We use the US Census tool "On the Map".  Instructions for the tool here:
To set a basis for discussion, consider the following chart showing GHG emissions in California.   (click image to enlarge)

Transportation is 40% of GHG emissions, of which passenger vehicles are 28%.  Passenger vehicles includes pickup trucks but not freight or delivery trucks.  Pick-up trucks generate approximately one third of light-duty-vehicle GHG emissions.  Pick-up trucks are used by construction workers or service-workers like plumbers.  No plumber is going to bike around to customers with clogged drains.


Sunnyvale Commute In/Out Data

US Census data for the 15 years from 2002 to 2017 shows that:
  1. The number of workers living in Sunnyvale increased by just over 12,000,
  2. The number commuting out of Sunnyvale for work increased by nearly 13,000,
  3. The number of workers in Sunnyvale increased by just over 10,000,
  4. The number of those both living and working in Sunnyvale decreased by 469,
This is seen in the two images from "On The Map" below (click on images to enlarge)

Sunnyvale Work & Commute
2002 & 2017
Employed in Sunnyvale = 78,329
Reside in Sunnyvale = 58,772
Commute Out = 49,164
Commute In = 68,771

Employed in Sunnyvale = 88,572 = 10,243 increase from 2002
Reside in Sunnyvale = 71,175 = 12,403 increase from 2002
Commute Out = 62,086 = 12,922 increase from 2002
Commute In = 79,483 = 10,772 increase from 2002

Above data shown in bar chart below (click on image to enlarge):

Sunnyvale Totals:
Resident Workers, non-Resident workers and Commuters.

Green bars show the increase in each category.
Increase in outbound commuters exceeds increase in residents 
Increase in inbound commuters exceeds increase in workers 

Clearly, the data shows that despite increased housing in Sunnyvale there is more outbound commuting.  Similarly, despite increased job numbers, there is more inbound commuting.  US Census data thus shows that increasing the opportunity to live and work in Sunnyvale is completely ineffective in lessening commuting either in or out.


Sunnyvale VMT Data

Outward Bound:
We look first at those commuting from Sunnyvale to other towns to work.  More important than how many commute in or out is how far they travel.  If people are simply commuting a mile or two between neighboring towns it doesn't matter how many are doing so.  Fortunately, "On The Map" also shows how far people commute and how that has changed over 15 years as seen below (click graphic to enlarge).

Commute distance - outward bound commuters
2002 (left) & 2017 (right)

The increases are key.  The number commuting 25-50 and over 50 miles increased more than those commuting less than 10 miles.  This is summarized in the chart below (click image to enlarge):

Sunnyvale - Outward Commuting
Number of Commuters vs Miles Traveled

One thing to note above is that the increase in those commuting out of Sunnyvale more than 25 miles was greater than the increase in those commuting less than 10 miles.  In other words, a "reverse sprawl" is happening - there is a significant increase in those commuting out of the job centers of Silicon Valley.  This has a dramatic effect on VMT because one person commuting 50 miles produces the same VMT as 5 people commuting 10 miles.

We can see this when we calculate the VMT for commuters from Sunnyvale.  We approximate the VMT corresponding to the above data by taking the mid-point of each mileage range (assume 60 miles for ">50") and multiply the total number of commuters in each range by that mid-point.

For example, to calculate the total VMT for all those commuting less than 10 miles, "< 10", we multiply the average of the mileage range, [5 miles = (10-0)/2], times the total number of people commuting that range in 2002, (42,435).  I.e., the 2002 VMT for those commuting less than 10 miles was:
5 miles x 42,435 commuters = 212,175 VMT.  

Doing this for all the data for commuters leaving Sunnyvale for work elsewhere is shown in the table below:
VMT for those Commuting OUT of Sunnyvale

The above data is graphed below (click on image to enlarge):

As an example of the above data in context, we see that in 2017, the 19% of commuters who traveled more than 25 miles contributed 62% of the total of over one million VMT.

We see that the hypothesis that "adding more housing reduces VMT and therefore GHG emissions" is counterfactual for outward bound commuting.

Inward Bound:

We do the same thing for those commuting into Sunnyvale.  Same drill, different data.  See below - click on images to enlarge:
Commute distance - Inward Bound Commuters
2002 (left) & 2017 (right)

Sunnyvale - Inbound Commuting
Number of Commuters vs Miles Traveled

For the inbound commute VMT data table it is interesting to note the 29% increase in inward bound commuting.  This was much less than the 47% increase in outward bound commuting VMT seen earlier.  We might see the two commute VMTs (in and out) converge!

Graph of table data:

No surprises at this point. People are continuing to commute from further and further out, despite the increase in housing in Sunnyvale over the 15 year span covered.  People want that single family house and if they can't get it here, they will move to where they can get it.  If not Livermore, then Austin, TX, or Charlotte, NC.

This is not very different from the SF Bay Area as a whole as I showed using similar methods.


We have only looked at VMT for car commuting.  Everything above does not include VMT for all the travel used for other purposes by cars.  Commuting is only 27% of individual automobile use as seen in the following two graphs from US government agencies.

From Federal Highway Administration document

If all other auto use stays the same, to achieve a 15% reduction in total car VMT would require that 27% to go to 12% = only 44% of current use.  That equates to a 55% reduction in commuting.  Nor does that count the VMT of heavy duty trucks, which have much worse CO2 emissions.  The extraordinary difficulty in achieving such extreme reductions is compounded when one considers that pickup trucks are typically used in the trades for work.  Plumbers, for example. are not going to start biking from one house with a plugged-up drain to another.

Example Cities

So, where are all these long commutes to and from?  "On The Map" tells us that too!  We select destinations when we set up an analysis and get the list seen below:

Cities Sunnyvale Residents Commute To
2002 (left) & 2017 (right)

I circled a few in red.  In 2002 the number of commuters to Santa Cruz was 111. And 15 years later it was 107.  Basically the same.  Commuters from Sunnyvale to Livermore numbered 117 in 2002, 158 in 2017.  Sunnyvale to Sacramento: 229 in 2002, 245 in 2017.  Pleasanton; 631 in 2002, 471 in 2015.

This pretty much puts paid the idea that people desire nothing more than to "walk to work".  All the cities circled above have much cheaper housing than Sunnyvale, yet over a span of 15 years, roughly the same number of people commute from Sunnyvale to these cities.

Yet another nail in the coffin of the "build more housing so everyone can walk to work" mantra.


The counterfactual myth that building more will lessen VMT would normally be harmless because people will do what they want to do.  When it comes to getting a job or choosing where to live, data clearly shows people don't care about VMT in the slightest.  What well-intentioned people in Sacramento decree doesn't really matter.

The realization of this myth under the guidance of the bureaucrats will be reduced parking and freeway flow because "everyone will walk or bike to work".  In reality what will happen is that parking will become a nightmare as will freeway traffic - more and more people will leave CA because traffic and parking just gets too crazy. 
If you can!  Might get stuck on "the 5"

Which is probably just as well.  If the government agencies in charge of making life better keep making life worse then people will vote with their feet, because they really have little voice in this.  

By roughly 2025, battery prices will decline enough that Electric Vehicles (EVs) will reach cost parity with Internal Combustion Engine Vehicles (ICEVs).

By then it will be clear that is the only real solution to transport-generated GHG emissions.

You might think that would free us from this tyranny of VMT.  It won't.  Urban planning depts. in all universities adhere to the myth of "cars bad, buses good, everyone wants to walk to work".  They will find some other excuse to impose their "vision".

But at least you, dear reader, will know it as a cult - like the flat Earth movement.

For now, this is...