The Road Not Taken

Two roads diverged in a yellow wood,
And sorry I could not travel both
And be one traveler, long I stood
And looked down one as far as I could
To where it bent in the undergrowth;

Then took the other, as just as fair,
And having perhaps the better claim
Because it was grassy and wanted wear,
Though as for that the passing there
Had worn them really about the same,

And both that morning equally lay
In leaves no step had trodden black.
Oh, I kept the first for another day!
Yet knowing how way leads on to way
I doubted if I should ever come back.

I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I,
I took the one less traveled by,
And that has made all the difference.

Robert Frost

Altoona Pennsylvania adopts Land Value Tax

The Altoona Mirror reports that Altoona Pennsylvania adopts Land Value Tax, sadly the report headlines on confusion. Altoona property tax bills confuse property owners :

“City Council voted to adopt “land value tax” in 2002, on the urging of The Center for the Study of Economics in Philadelphia, whose president, Joshua Vincent, had made a presentation the year before.

Land value tax shifts the basis for property tax to assessed value of land and away from assessed value of buildings. It’s designed to encourage development and discourage speculative hoarding of ground.

While 16 cities and two school districts in Pennsylvania use land value tax, Altoona this year became the first municipality in the country to go as far as to rely on land value alone.

Council introduced the practice with a 20-percent shift toward taxing on land alone, followed by successive annual shifts of 10 percent, until the transformation was complete.

Because collective assessed value of land in the city is one-seventh as much as assessed value of land and buildings combined, the city had to increase millage by a factor of seven to generate the same revenue.

That land millage is now 369 mills.

Applied to the $24.59 million assessed value of land in the city, it generated $9 million for 2011, theoretically.

Because the new millage is seven times higher than the millage under the old system, individual property owners pay less if their land value is less than one-seventh of their total assessed value – the amount that was the basis for taxation under the old system.

Conversely, owners pay more if their land value is more than one-seventh of their total assessed value.”

H/T Matt Yglesias

A survival analysis-based choice set formation approach for single-destination choice using GPS travel data

SDC figure

Recent working paper:

This research investigates how land use and road network structure influence home-based single-destination choice in the context of trip chains, using the in-vehicle GPS travel data in the Minneapolis-St. Paul Metropolitan area. We propose a new choice set formation approach which combines survival analysis and random selection. Our empirical findings reveal that: (1) Accessibility and diversity of services at the destination influences individuals’ destination choice. (2) Route-specific network measures such as turn index, speed discontinuity, and trip chains’ travel time saving ratio also display statistically significant effects on destination choice. Our approach contributes to methodologies in modeling destination choice. The results improve our understanding on travel behavior and have implications on transportation and land use planning.

This paper is part of Arthur Huang’s Dissertation.

Racial Dot Map

Cross-posted at Racial Dot Map . Every person is a dot.

Racial Dot Map


The Racial Dot Map shows at the level of one dot per person the racial makeup of every census block in the US. This map was created by Dustin Cable of the Cooper Center.  Below is a zoom on Minneapolis.

Cable writes:

“While Minneapolis and St. Paul may appear purple and racially integrated when zoomed out at the state level, a closer look reveals a greater degree of segregation between different neighborhoods in both cities. While some areas remain relatively integrated, there are clear delineations between Asian, black, and white neighborhoods.”



Dustin Cable's Racial Dot Map

Why isn’t NASA in USDOT?

The United States Department of Transportation was formed in 1966 and began operations in 1967 in the Johnson administration to consolidate a set of federal agencies dealing with transport, which had been in various places. One of the most important components was the Federal Highway Administration, which Wikipedia notes:


The organization has several predecessor organizations and a complicated history. The Office of Road Inquiry (ORI) was founded in 1893. In 1905 that organization’s name was changed to the Office of Public Roads (OPR) which became a division of the United States Department of Agriculture. The name was changed again to the Bureau of Public Roads in 1915 and to the Public Roads Administration (PRA) in 1939. It was then shifted to the Federal Works Agency which was abolished in 1949 when its name reverted to Bureau of Public Roads under the Department of Commerce.

The Urban Mass Transit Administration, founded in 1964 was in HUD (and even a few years after USDOT was formed).

The National Aeronautical and Space Administration was founded in 1958 by incorporation of the National Advisory Committee for Aeronautics, itself formed in 1915!

NASAToday USDOT has the following units:

Two former agencies, Transportation Security and the Coast Guard, were moved to Homeland Security.

USDOT’s mission is to “Serve the United States by ensuring a fast, safe, efficient, accessible, and convenient transportation system that meets our vital national interests and enhances the quality of life of the American people, today and into the future.”

NASA’s Vision is “To reach for new heights and reveal the unknown so that what we do and learn will benefit all humankind.”

So the scopes are a bit different, USDOT cares about Americans, while NASA cares about humanity. NASA is about exploring the unknown and USDOT is about the exploiting the known. But without a sufficient dialog between the two, the unknown never becomes known. Research and practice need to be integrated for progress to be made.

Some Reasons NASA should be in USDOT

  1. It will decrease the myopia of USDOT, encouraging that organization to have a longer term and far broader perspective on transportation, now and in the future.
  2. It will install in USDOT a sense of the future possible
  3. It will increase coordination between NASA and mainstream transportation practice (especially, but not only aviation), tying research more closely to implementation.

Some Reasons NASA should not be in USDOT

  1. It will diminish NASA’s independence.
  2. NASA will have to compete more directly with today’s needs for federal funding and attention. The 2012 NASA budget was $17.7 B, while USDOT was $72.6 B. So NASA would be the second largest agency in USDOT, following only FHWA, but ahead of FAA and FTA.
  3. Government agencies should be smaller and more focused. USDOT will lose focus with NASA on board, but more importantly, NASA will lose focus responding to USDOT issues.
  4. The skills and missions of the  agencies are very different, and irreconcilable. The short term is the enemy of the long term.

Causality in the Link Between Road Network Growth and Regional Development

StatePanel image

Recent working paper:

  • Iacono, M. and D. Levinson (2013) Causality in the Link Between Road Network Growth and Regional Development

    This paper investigates the relationship between the growth of road networks and regional development. We test for mutual causality between the growth of road networks (which are divided functionally into local roads and highways) and changes in county-level population and employment. We employ a panel data set containing observations of road mileage by type for all Minnesota counties over the period 1988 to 2007 to fit a model describing changes in road networks, population and employment. Results indicate that causality runs in both directions between population and local road networks, while no evidence of causality in either direction is found for networks and local employment. We interpret the findings as evidence of a weakening influence of road networks (and transportation more generally) on location, and suggest methods for refining the empirical approach described herein.

Modeling the Commute Mode Share of Transit Using Continuous Accessibility to Jobs

MCMS image

Recent working paper:

This paper presents the results of an accessibility-based model of aggregate commute mode share, focusing on the share of transit relative to auto. It demonstrates the use of continuous accessibility — calculated continuously in time, rather than at a single or a few departure times — for the evaluation of transit systems. These accessibility calculations are accomplished using only publicly-available data sources. A binomial logit model is estimated which predicts the likelihood that a commuter will choose transit rather than auto for a commute trip based on aggregate characteristics of the surrounding area. Variables in this model include demographic factors as well as detailed accessibility calculations for both transit and auto. The model achieves a ρ2 value of 0.597, and analysis of the results suggests that continuous accessibility of transit systems may be a valuable tool for use in modeling and forecasting.

This is based on Andrew Owen’s Master’s Thesis.

The Hyperloop Boarding and Alighting problem

It has been noted that there is a very short time between Hyperloop capsules arriving at the Hyperloop station. This potentially makes boarding and alighting difficult, since there is no guarantee everyone will take their seats and be strapped in before the next capsule arrives. This requires either the following capsule to deploy its emergency brake (with bad consequences), or the main capsule to depart without everyone properly strapped (with bad consequences). Even with handlers like a ski-lift, this is less than optimal.


There is a simple solution for this. Pre-load passengers into removable chairs, and then automatically load the removable chairs into the Hyperloop passenger capsule. The pre-loading can take as much time as required, be conducted offsite at the station, with many parallel removal chairs loading bays, and assures that the main infrastructure is fully utilized.

There are a few options with design. Would the chairs be individual, or a set of chairs in series, and thus have one or multiple passengers? (And thus would the Hyperloop passenger capsule have one or multiple passenger chair units?

Would it slide horizontally into the Hyperloop capsule, or be loaded aerially?

The removable chair loading system would have multiple switches, so if a capsule were not ready, the next one could be loaded into the system.

WallE Chairs

In other words, the chairs should not be built into the passenger capsule (as drawn in the alpha-proposal, reproduced here), but into a removable unit. This unit would be robotically unloaded and offloaded.

It is much like removable car seats for babies, with the parents replaced by robots. Or like the chairs in Wall-E, with the chairs physically grounded, and then loaded into the Hyperloop passenger capsule.

I hereby open-source this idea, and don’t have time to develop it further as I am busy with other activities.