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Portland is a PR machine for light rail & streetcar

Here are Some Facts About Portland Oregon          

“It must always be remembered how cost-effectiveness works in the public sector: the cost IS the benefit.” - author unknown




False Promises: High Density will Reduce Traffic Congestion


Here is The Usual Claim


Here is the rest of the story:



from The Sierra Club:

The data show that auto trips decline with increasing population density, as expected. These data indicate a near linear increase in public transit and walking-biking trips per capita with increases in population density above 4500 persons/square mile. Transit trips increase with density from a low of about 0.07 trips/capita below 4500 persons/square mile (about 4 households/residential acre in a residential-only zone) steadily up to 1.03 at the highest density of 60,000 (perhaps 100 hh/res ac in a mixed-use zone). Walking and bicycling trips also increase steadily with density above 4500 persons/square mile from 0.3 per person to 1.55 at the highest density aggregate.




Data Source:

Dunphy and Fisher ("Transportation, Congestion, and Density: New Insights," Transportation Research Record, No. 1552, Washington DC: Transportation Research Board, Nov. 1996, Table 5) aggregated the 1990 National Personal Transportation Survey (NPTS) by the population per square mile of the household?s ZIP code.


Per/Sq Mi

Auto Trips/Cap

Tr Trips/Cap

Walk\Bike/C ap

2000

3.28

0.08

0.33

2500

3.46

0.07

0.28

3500

3.34

0.08

0.29

4500

3.51

0.06

0.3

6250

3.29

0.11

0.36

8750

2.92

0.16

0.45

30000

1.9

0.5

0.95

60000

0.59

1.03

1.55

Density vs. Daily Trips, from Dunphy and Fisher

with Typical city and Total Auto trips added



Per/Sq Mi

Typical Central City


Auto Trips/C ap


Total Auto Trips


Tr Trips/C ap


Walk\B ike/Cap

2000

Indianapolis

3.28

6,560

0.08

0.33

2500

Tucson

3.46

8,650

0.07

0.28

3500

Portland

3.34

11,690

0.08

0.29

4500

San Jose

3.51

15,795

0.06

0.3

6250

Seattle

3.29

20,562

0.11

0.36

8750

Providence

2.92

25,550

0.16

0.45

30000

NYC=23k

1.9

57,000

0.5

0.95

60000

2.5 x NYC

0.59

35,400

1.03

1.55

Click here for bigger table 4

Here is the original Dunphy and Fisher FIG 4 and table 4. Notice the curve is much more gentle.That is because they chose a log display to more properly show the relationship between density and auto trips. You can plainly see that there are only three data points that show a useful reduction in driving! With so few data points, the conclusion is far from certain.

Density Increases Congestion

Driving DOES NOT Decrease Until You Triple Portland’s Density


Since driving per person stays about the same, congestion goes up with density:

more people = more cars = more congestion.

PDF of this Chart