The congestion question: Will adding lanes to Highway 1 deliver “congestion relief”?
Here are six counterposed responses:
The answer is always yes. With predict-and-provide transportation planning, the answer is always “yes,” or at least “congestion would be worse if we did not add lanes.”
Predict-and-provide works this way: Predict increases in population, employment, and driving over a period of years. Report measures of existing peak traffic, congestion and time delays, forecast more vehicles by a certain date, and run a computerized traffic model predicting the increased future congestion and time delays. Then run the model showing that providing the increased capacity of added lanes will accommodate more vehicles with less congestion. Neglect or under-report generated traffic, and isolate the congestion question from concerns about sustainability and alternatives to more cars. Present “doing nothing” as the only project alternative, under which congestion is predicted to grow worse, so adding lanes must be the correct approach. These lanes are always called “improvements.”
The Common Sense Answer #1:
The answer is yes. This refers to the common sense view a driver may have while stuck in traffic on Highway 1: “I see two lanes of slow traffic in front of me. This is a pain. If there was just another lane alongside here, surely the traffic would flow better.” Years ago, the Sentinel editorialized: “A five-year-old can see that another lane is needed.”
The Common Sense Answer #2:
The answer is no. Some people with long experience, seeing what happens after freeway lanes are added in urban areas with peak-period traffic congestion, have noted a peculiar thing: While traffic congestion may initially be reduced, after some years a freeway typically becomes congested again at a bigger scale, because more single-occupant cars occupy a lot of road space. We built it, and they came.
The Research Actual Outcomes Answer:
The answer is no. For “aggregate outcomes” we must look into reporting from transportation studies that investigate what the results have been over time, of adding freeway lanes and highway capacity in California and elsewhere. A study on Generated Traffic and Induced Travel that aggregates the findings of many referenced studies was prepared by the Victoria Transport Policy Institute, updated in January 2015. For a peak period congested freeway such as Highway 1 with high latent demand, the study finds in Figure 3 that at ten years after capacity expansion, around 90 percent of the new capacity may be anticipated to be filled with generated traffic. See also this recent study by U.C. Davis.
The Opportunity Cost Considered Answer:
The answer is no. The “predict-and-provide” approach outlined above tends to ignore or discount the possibilities of any other reponses to traffic congestion. Expensive freeway projects lose us the opportunity to use those public funds to create a sustainable future.
The Climate Action Considered Answer:
The answer is gigantically no. Climate action means starting from a completely different question: Will we intelligent human beings take the steps necessary to prevent the destabilization of Earth's climate, which would be ruinous to the civilization we want to keep going? If we do succeed in taking the necessary steps, which will include placing an incrementally persuasive price on carbon emissions, then that pricing and other measures will result in a significant reduction in voluntary vehicle miles traveled. Then an expanded Highway 1 is a wasted investment for the future. Expansion of Highway 1 is, in other words, like anticipating failure on climate action.