Guest Commentary: Be Wary of Caltrans Pattern of Science Denial on GHG

Open letter to Davis BTSSC (Transportation Commission)

To: Chair Jessica Jacobs and members, Davis BTSSC

RE: Potential Endorsement of I-80 Yolo widening before Draft EIR released

BTSSC will be asked tonight (item 6b) to endorse a letter to partner with Caltrans to endorse I-80 widening by supporting a new and untested program of mitigation that could negate local cities’ greenhouse gas reduction programs (CAAP/CAP).

You will be asked to sign before even seeing the draft Environment Study (DEIR) or the mitigation plans. This is not due out for 30 days.

I urge caution based on the study by Professor Susan Handy’s group at UC Davis Institute of Transportation Studies. (ITS)

The below bar chart from that UCD ITS study compares induced travel projections by Caltrans to the forecast by the National Center for Sustainable Transportation model. Caltrans’ lower forecasts in the EIRs were used to justify spending hundreds of millions of dollars on these five projects. The study shows Caltrans consistently understates the amount of travel & GHG to be mitigated. And in two projects Caltrans assumed no induced demand.

Induced demand has been accepted science in the transportation world for over thirty years now. The science was upheld in the 1990 California case Citizens for a Better Environment vs Deukmejian, et al.   It was an inconvenient truth Caltrans has worked three decades to get around. It was not until the beginning of 2020 after the 2013 passage of Bill SB 743 that EIRs had to focus on reducing Vehicle Miles Traveled (VMT).

Caltrans has been in denial of the science on traffic, which has been confirmed by hundreds of studies out of UC Davis, UC Berkeley, and the Texas Transportation Institute, among many other places worldwide.

I will also note the Caltrans HQ (not the local Caltrans district doing the project) has just recently implicitly acknowledged three decades of understating the impact of the wider freeway on VMT and GHG in its CEQA guidance specifically:

– 30-year program of installing HOV lanes to reduce congestion and improve air quality were mismodeled. The billions spent here did not address air quality concerns by reducing travel or reducing congestion, i.e. they do not cause people to car pool more.

– The Caltrans new innovation “Managed Lanes” (aka Express lanes/variable toll pricing/HOV) are not “environmentally sustainable” as they do not overcome the GHG impact of regular freeway lanes.

Beware of GEEKs bearing gifts: Caltrans gets “free money” from feds & state gas taxes, so it is not unreasonable to believe that motivated reasoning is at play. There is a history of bias in the environmental analysis of these projects to justify using funds to build even wider freeways instead of funding local transit agencies. This tendency was shown in the Caltrans 2022 study of increasing mobility in the I-80 corridor: upgrading the Capitol Corridor was studied, found more cost-effective, then ignored.


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Disclaimer: the views expressed by guest writers are strictly those of the author and may not reflect the views of the Vanguard, its editor, or its editorial board.

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  1. Alan Hirsch

    Link to primary sources: Credibility is important when strong statement like I made above are made. These are my important End Notes to this article…that link to primary sources.
    References/end notes to piece on Caltrans EIR analysis methods:
    [1] The question about if a mitigation is valid is about if it is a truely “additive” change, Will Caltrans VMT mitigation offset fund truely new “additive” projects beyond what is already planned and counted in a city’s CAP/CAAP or just double count what is already planned?.  For example, the West Sacramento CAP GHG reduction Plan already calls for an ambitious 40% reduction in car travel. Any mitigation paid for by Caltrans funding increase transit/micro transit and car-free housing should be on top of this 40%—if not  the Caltrans VMT mitigation will be double counted and not be true mitigation. Any city that accepts Caltrans mitigation funds will be faced with same problem. This type of mitigation plan (VMT banking) is untested in court. See John Oliver’s tongue and cheek critique on how similar Carbon Offset plans are gamed.
     [1] Volker, Jamey et al:  Environmental Reviews Fail to Accurately Analyze Induced Vehicle Travel from Highway Expansion Projects

    [1] Citizens for a Better Environment vs Deukmejian, et al. This case put to a conclusive test Caltrans argument that wider freeways reduce congestion and air quality. Conclusive scientific evidence was present from decades of experience that when you widen a freeway, more traffic is generated to fill it. This article in Wired magazine discussed in more depth and gives real world examples of when freeways are removed traffic evaporates: What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse. The City of Davis succesfully tested this on 5th Street with its “road diet,” a change the Davis Public Works Department resisted for a decade.
    [1] SB743 and it finally focusing Caltrans on VMT/GHG reducts and that impact on EIR and need to reduce VMT is discussed in “Rethinking How We Build So Californians Can Drive Less”  
    [1]  Decades of research are cited by Professor Susan Handy, Director of the National Center for Sustainable Transportation, in recent article: Increasing Highway Capacity Unlikely to Relieve Traffic Congestion EPA published this 16 page “Induced Travel Demand Literature Review” 20 years ago. Inconvenient truths are hard to institutionalize.
    [1] [1] Rail alternative for I-80 ignored. Caltrans District 3&4. “I-80 Comprehensive Multimodal Corridor Plan (I-80 CMCP). Draft of 1/22 See Page 77 table 5.13 Benefit cost ratios for different alternatives by segment (segment 6 is Davis/Causeway). The rail alternative to improve I-80 mobility includes upgrades like 110 MPH trains, ½ hour service and a high bridge over Sacramento River so trains are not stopped by river traffic, pg. 60. Rail ridership would triple, pg. 66.  The I-80 CMCP is not found on public Caltrans site and has never been shared with Yolo elected–its only show, only Solano County website.   Of note, Caltrans claim in document Yolo Transit District was in the the plan’s preparation but a public record request show no such input or request.for input 



    1. Matt Williams

      Thank you Alan for breaking your article into two parts the way you did.  As a result, the article itself is much easier (and less daunting) to read … and your addendum to the article in the form of the comment above makes the article more powerful.

      Well done.

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