Vanishing Automobile update #13

Increased Congestion and

What to Do about It


Contrary to well-publicized claims by the anti-auto Surface Transportation Policy Project, cities that have emphasized transit over highways experienced the greatest increases in congestion over the past two decades. Data from the Texas Transportation Institute reveals that cities that concentrated on highways instead of transit did fairly well at minimizing the burden of congestion on their residents. This makes sense because few transit investments carry as many passenger miles as comparably-priced highway investments. But highway investments alone won't solve congestion: What is also needed is a toll system that charges more during congested periods than other periods.

Texas Mobility Report

The Texas Transportation Institute put out its annual mobility report on May 7, 2001, showing that congestion in most U.S. urban areas was worse in 1999 than the year before. The Institute's carefully worded publication does not take sides on the vexatious question of what to do about congestion.

But the study does quantify a lot of the problems related to congestion. In the 68 urban areas in the study, researchers estimated that congestion cost $78 billion and wasted 6.8 billion gallons of fuel and 4.5 billion hours of people's time in 1999. These numbers make for exciting newspaper headlines, but (as described on pp. 387-388 of The Vanishing Automobile) have to be taken with a grain of salt as they are based on on a lot of assumptions about road capacities and designs.

For example, the Institute estimates that congestion cost people in the San Francisco Bay Area (including the San Francisco-Oakland and San Jose urban areas) 227 million hours and $3.9 billion in 1998, which works out to about 750,000 hours and $13 million dollars per working day. By comparison, the California Department of Transportation estimates that congestion cost about 112,000 vehicle hours (which works out to about 150,000 person hours) and $1.25 million per day. Caltrans' numbers are significantly smaller than those of the Texas Transportation Institute.

This is not to say that one number is right and the other wrong. Both are in fact fairly crude estimates. The important point is that we have to be careful using these numbers. In fact, Texas Transportation Institute data are most reliable when comparing the changes in congestion over time, and less reliable when comparing congestion among urban areas for any single year.

For example, the report consistently rates Los Angeles as the nation's most congested urban area, while New York is somewhere around number thirteen. Yet, relative to Los Angeles highways, most New York highways tend to have narrower lanes, shorter merge lanes at on- and off-ramps, and tighter curves, all of which reduce the flow capacities of New York freeways. Since the Institute doesn't take these variations into account, New York congestion may actually be worse than in Los Angeles.

The STPP Response

This weakness in the data is not recognized by the Surface Transportation Policy Project (STPP), an anti-auto, pro-transit group that issued a report on the same day as the Texas study claiming that "commuters suffer most" in urban areas "with the fewest transportation choices." "Transportation choice" is a euphemism, of course, for spending transportation dollars on transit, especially rail transit, instead of highways.

STPP used the Texas institute's data to compare congestion in various urban areas in 1999 -- exactly the kind of comparison that the Texas data is least suited for. STPP also added its own factors in a convoluted attempt to measure "congestion burden" rather than just the cost of congestion. STPP's congestion burden index is the Texas institute's 1999 travel rate index times the percentage of commuters who drove to work in 1990.

Never mind that this is mixing 1990 and 1999 data. Even if this were not a problem, STPP's index produces some very specious results. For example, according to the Texas Transportation Institute's data, the average Bostonian spends twice as many hours stuck in traffic each day as the average Las Vegan. Yet because Boston has more transportation choices than Las Vegas, STPP ranks Boston one of the least congestion-burdened urban areas and Las Vegas as the second-worst congested-burdened metro area in the nation.

Just why is sitting in traffic less of a burden because there is rail transit system that doesn't go where you need to go? STPP's index may confuse cause and effect. High congestion may force some people to ride transit, but that doesn't mean they are less burdened, especially since transit trips are generally slower than auto trips even in congested conditions.

A Valid Use of TTI Data

If inter-metro area comparisons of Texas institute data are not valid (and made even less valid by STPP's politically contrived manipulations), are the Texas data worthless? No, the data are particularly valuable where they provide a time series from 1982 through 1999. These time series show what most urban residents know: that congestion is getting worse in almost every urban area. Moreover, the data are valid for making inter-urban area comparisons of the changes in congestion over that time period.

For example, it may not say much to say that Los Angeles is ranked number one and New York number thirteen in 1999 congestion because this ranking fails to account for the superior capacities of Los Angeles freeways. But it is more meaningful if the data show that New York congestion increased 50 percent faster from 1982 to 1999 than Los Angeles congestion. This suggests that whatever Los Angeles is doing may be working better at solving congestion than what New York is doing.

The Texas study uses several different measures of congestion, including:

There is a strong correlation (r-squared) between most of these indices. For example, there is a 98 percent correlation between the Travel Rate and Travel Time indices, and a 93 percent correlation between the Travel Rate Index and hours of delay per capita. (There is less than a 60 percent correlation between any of these measures and STPP's congestion burden index.)

Changes in Congestion Over Time

Looking at the changes in the Travel Time Index from 1982 to 1999, it turns out that New York congestion did increase 50 percent faster than Los Angeles congestion. Hours of delay per capita in New York increased 2.5 times more than in Los Angeles. Thus, having all those rail lines in New York doesn't seem to have eased the burden of congestion all that much.

The table below shows the percentage change in the travel time index, travel rate index, roadway congestion index, and hours of delay per capita (1999 hours minus 1982 hours) for each of the urban areas in the Texas study. The delay per capita is shown as a difference rather than a percentage because percentage changes can be misleading. An urban area which moved from nearly no congestion in 1982 to some congestion in 1999 can have a huge percentage increase in the hours of delay per capita even though the 1999 hours of delay remain relatively small.

A lot of factors caused congestion to increase in some regions faster than in others, including population growth, urban layout, and the location and distribution of employment centers. But the one important factor under the control of transportation planners is how transportation funds are spent. Over the past decade or so, the leaders of many urban areas, including Portland, the Twin Cities, and San Diego, have openly given up on highways to relieve congestion and funneled transportation dollars into transit instead. Other regions, such as Houston, Phoenix, and Kansas City, decided to stick with highways.

Results: Transit Emphasis Equals More Congestion

Table one shows a clear result. Urban areas that focused on transit had the greatest increases in congestion. My own home town of Portland suffered the greatest increase in the Travel Time Index, the second-greatest increase in the Travel Rate Index (scoring a fraction of a percent less than San Diego), and large increases by the other measures as well.

All of the top seven urban areas (as ranked by change in Travel Time Index) became fixated on rail rather than roads sometime in the 1980s or 1990s. Number eight on the list, Las Vegas, has been growing at nearly 6 percent per year -- far faster than any other urban area -- which is far faster than road agencies can build roads even if they have the political support.

Meanwhile, urban areas that focused on highways had relatively low increases in congestion. Thanks to aggressive construction of toll roads, Houston has barely recorded an increase in congestion. Phoenix and Kansas City also did well.

Table One
Change from 1982 to 1999
(Ranked by Change in TTI)

Urban area             TTI      TRI      RCI  Hours/capita
Portland OR            151%     130%     153%      30
Twin Cities MN         149%     126%     182%      35
San Diego CA           145%     130%     158%      29
Boston MA              145%     125%     145%      30
New York NY            144%     120%     149%      27
Seattle WA             144%     126%     121%      34
Atlanta GA             143%     125%     165%      42
Las Vegas NV           143%     127%     171%      16
Sacramento CA          140%     122%     158%      25
San Bernardino CA      139%     125%     159%      32
Denver CO              138%     123%     146%      32
Cincinnati OH          137%     121%     160%      29
Tacoma WA              136%     122%     159%      22
Indianapolis IN        136%     121%     173%      34
Albuquerque NM         136%     120%     182%      30
Dallas TX              135%     120%     135%      38
Detroit MI             135%     119%     135%      29
Washington DC          132%     121%     135%      28
Austin TX              131%     117%     145%      36
Los Angeles CA         131%     119%     122%      26
SFO-Oakland CA         131%     119%     131%      22
Columbus OH            130%     117%     167%      42
Chicago IL IN          130%     120%     138%      22
Milwaukee WI           130%     118%     148%      24
Baltimore MD           129%     117%     143%      23
St. Louis MO           129%     117%     118%      33
Charlotte NC           129%     119%     133%      27
Ft. Lauderdale FL      127%     119%     170%      22
Salt Lake City UT      126%     116%     152%      16
Miami FL               126%     116%     129%      25
Cleveland OH           126%     116%     146%      18
Fort Worth TX          125%     116%     132%      28
Phoenix AZ             125%     116%     127%      19
Louisville KY          125%     114%     140%      29
San Antonio TX         125%     118%     148%      19
Providence RI          124%     113%     136%      25
Philadelphia PA        124%     112%     129%      17
Colorado Springs CO    123%     113%     170%      19
Tucson AZ              123%     113%     131%      19
Memphis TN             123%     112%     138%      19
Orlando FL             122%     113%     128%      32
Jacksonville FL        122%     113%     133%      25
Fresno CA              122%     113%     149%      14
Kansas City MO         118%     109%     158%      22
San Jose CA            117%     109%     111%      22
Nashville TN           117%     109%     122%      29
Honolulu HI            117%     112%     134%      12
El Paso TX             116%     111%     152%      12
Omaha NE               116%     110%     145%      17
Oklahoma City OK       115%     108%     135%      13
Norfolk VA             115%     108%     109%      16
Salem OR               114%     107%     152%      12
Eugene OR              113%     106%     172%       9
Tampa FL               112%     107%     121%      22
Houston TX             112%     108%     107%      23
Hartford CT            109%     105%     154%      12
Rochester NY           109%     105%     153%       7
Spokane WA             109%     104%     126%       7
Albany NY              107%     104%     167%       9
Boulder CO             107%     104%     151%       4
Bakersfield CA         107%     104%     143%       5
Brownsville TX         107%     104%     139%       3
Buffalo NY             107%     104%     136%       6
Laredo TX              106%     103%     111%       5
Pittsburgh PA          105%     103%     111%       8
New Orleans LA         104%     104%     108%       8
Beaumont TX            104%     102%     126%       5
Corpus Christi TX      103%     102%     125%       4

(The names of some urban areas were shortened for convenience; e.g. Portland-Vancouver to Portland.)

Thus, STPP's claim that huge investments in transit ease the burden of congestion is almost certainly disproven by Texas Transportation Institute's data. In fact, the leaders of most urban areas that have elected to focus on transit see congestion as a tool to get people to ride transit. As noted in The Vanishing Automobile (p. 112), Portland planners say that any relief from stop-and-go traffic (level of service F) "would eliminate transit ridership." A 1996 transportation plan for the Twin Cities places a moratorium on new roads in the hope that, "as traffic congestion builds, alternative travel modes will become more attractive" (Vanishing Auto, p. 465).

Thus, well-publicized efforts to increase "transportation choices" are almost certain to be accompanied by less-publicized decisions to increase highway congestion to force people to ride transit. This is exactly the opposite of the impression that STPP tries to convey.

The Real Congestion Solution: Value Pricing

Historically, congestion has increased because the states elected to pay for roads using highway user fees based mainly on a cents-per-gallon tax. The inflation of the 1970s drove up highway costs without concurrently increasing highway revenues, while the fuel-efficient cars of the 1980s drove down revenues per mile driven. This left highway builders financially unable to keep up with the growth in driving. As cars become even more fuel efficient, the long-term solution will be toll authorities, such as the one serving Houston, along with rush-hour premiums (value pricing) on those tolls.

Before that financial solution can be adopted, however, we have to overcome the political problem, which is that the anti-auto lobby has convinced many political leaders that transit, not roads, is the solution to congestion. Those who want a real solution to congestion must prove that this is not true before they can press for toll roads and value pricing.

Transit and Urban Growth

As a side note, a recent Brookings Institution review of census data concludes that transportation policy is an important factor in urban growth. "Cities built for cars grew" between 1990 and 2000, say Brookings/Harvard analysts Edward Glaeser and Jesse Shapiro, "but cities designed for mass transit and pedestrians tended to shrink."

Their report, City Growth and the 2000 Census: Which Places Grew, and Why, notes that "Cities with less than 65 percent of their commuters driving alone grew by less than 2 percent on average, while other cities grew by an average of more than 12 percent." Those who oppose automobiles might applaud this result since many of them also oppose growth. But those who believe that growth is an important part of their regional economies should pause before endorsing transit-intensive and road-starved transportation plans.

Thoreau Institute | Vanishing Automobile | Vanishing Automobile Updates