Guest Commentary: DISC Traffic Problems and Associated Vehicular Emissions Will not Be Solved by the Proposed I-80 HOV Lane Expansion

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Myths and Facts about Impacts of Freeway Lane Expansions on Traffic Congestion and Adoption Rates of Electric Vehicles

By Alan Pryor

Proponents of the proposed DISC project claim that the projected traffic congestion associated with the project will be solved soon in the future by the hoped-for I-80 freeway HOV lane expansion easing roadway congestion. The proposed freeway expansion project envisions the addition of one HOV lane on each side of the I-80 freeway freeway from from Hwy 113 on the west to the I-5/I-50 interchange in Scaramento and the I-80/Reed Ave interchange to the east.

Proponents also claim that the associated vehicular greenhouse gas (GHG) emission from the increased traffic to and from the DISC site will be substantially eliminated by the mass adoption of electric vehicles reducing tailpipe GHG emissions

Unfortunately, science shows us that the proposed addition of the two HOV lanes on the 20.8 mile stretch of the I-80 freeway expansion (one HOV lane on each side of the freeway) will actually induce further traffic and Vehicle Miles Traveled (VMT) on this stretch of the freeway. Methodology developed by the UC Davis National Institute of Sustainable Transportation (NIST) shows this phenomena is due to both short and long-term driver behavioral changes including taking longer and more frequent automobile trips, route shifts, and transportation mode shifts away from public transportation. The cumulative impacts will result in no relief from the current plague of I-80 freeway congestion.

Further, mass adoption of electric vehicles will take decades to substantially replace existing aging fossil fuel-powered vehicles resulting in no near term decreases of the additional GHG emissions resulting from new traffic associated with the DISC project. These emissions directly threaten the Davis goal of carbon neutrality by 2040 and Yolo County’s goal of net negative carbon emissions by 2030.

Myth #1 – The Proposed I-80 Expansion will Greatly Reduce Freeway Congestion for DISC Commuters Leading to Decreased Congestion for Local Drivers on Mace and Covell Blvd.

Facts – The following are excerpts from a Policy Brief issued by the UC Davis National Institute of Sustainable Transportation (NIST) entitled “Increasing Highway Capacity Unlikely to Relieve Traffic Congestion” authored by Professor Susan Handy of the Department of Environmental Science and Policy on October 1, 2015 (https://ncst.ucdavis.edu/research-product/increasing-highway-capacity-unlikely-relieve-traffic-congestion).

Issue

Reducing traffic congestion is often proposed as a solution for improving fuel efficiency and reducing greenhouse gas (GHG) emissions. Traffic congestion has traditionally been addressed by adding additional roadway capacity via constructing entirely new roadways, adding additional lanes to existing roadways, or upgrading existing highways to controlled-access freeways. Numerous studies have examined the effectiveness of this approach and consistently show that adding capacity to roadways fails to alleviate congestion for long because it actually increases vehicle miles traveled (VMT).

An increase in VMT attributable to increases in roadway capacity where congestion is present is called “induced travel”. The basic economic principles of supply and demand explain this phenomenon: adding capacity decreases travel time, in effect lowering the “price” of driving; and when prices go down, the quantity of driving goes up. Induced travel counteracts the effectiveness of capacity expansion as a strategy for alleviating traffic congestion and offsets in part or in whole reductions in GHG emissions that would result from reduced congestion.

Key Research Findings

Increased roadway capacity induces additional VMT in the short-run and even more VMT in the long-run. A capacity expansion of 10% is likely to increase VMT by 3% to 6% in the short-run and 6% to 10% in the long-run. Increased capacity can lead to increased VMT in the short-run in several ways: if people shift from other modes to driving, if drivers make longer trips (by choosing longer routes and/or more distant destinations), or if drivers make more frequent trips. Longer-term effects may also occur if households and businesses move to more distant locations or if development patterns become more dispersed in response to the capacity increase. One study concludes that the full impact of capacity expansion on VMT materializes within five years and another concludes that the full effect takes as long as 10 years.

Capacity expansion leads to a net increase in VMT, not simply a shifting of VMT from one road to another. Some argue that increased capacity does not generate new VMT but rather that drivers simply shift from slower and more congested roads to the new or newly expanded roadway. Evidence does not support this argument. One study found “no conclusive evidence that increases in state highway lane-miles have affected traffic on other roads” while a more recent study concluded that “increasing lane kilometers for one type of road diverts little traffic from other types of roads”.

Increases in GHG emissions attributable to capacity expansion are substantial. One study predicted that the growth in VMT attributable to increased lane miles would produce an additional 43 million metric tons of CO2 emissions in 2012 nationwide.

Capacity expansion does not increase employment or other economic activity. Economic development and job creation are often cited as compelling reasons for expanding the capacity of roadways. However, most studies of the impact of capacity expansion on development in a metropolitan region find no net increase in employment or other economic activity, though investments do influence where within a region development occurs.

Related research by the UCD NIST have produced an Induced Traffic Calculator whereby the increased VMTs resulting from a freeway expansion can be calculated. Using 2019 freeway usage data with the Sacramento-Roseville-Arcade Metropolitan Statistical Area (MSA) which includes Yolo County, the following result was obtained for two additional HOV lanes added in the proposed 20.8 mile stretch of I-80 work.

 

Source: https://travelcalculator.ncst.ucdavis.edu/

Further Information about the Induced Traffic Calculator can be found at https://travelcalculator.ncst.ucdavis.edu/about.html

The result of this calculation show that the addition of two HOV lanes on I-80 over the proposed 20.8 miles of the freeway will result in an additional 217.6 million miles per year of vehicle miles traveled! So much for relieving congestion.

Caltrans now recommends in its Transportation Analysis Framework (TAF) that the calculator be used where possible to estimate – or at least benchmark – induced VMT: “In cases where the NCST Calculator can be directly used, it should either be used exclusively or used to benchmark results from a [travel demand model]” (Caltrans, 2020, p. 14). Caltrans’ recommendation is supported by the report of a panel of experts convened by Caltrans to guide its choice of induced travel estimation methods for the TAF (Deakin et al., 2020).

Myth #2 – Electric Cars Will Dominate New Vehicle Sales Soon and Combined with Increased Usage of Public Transportation  Will Mostly Eliminate Additional Auto Emissions Resulting from New DISC Commuters.

Facts DISC advocates claim rapid expansion of electric vehicle use by future DISC commuters combined with increased use of mass transit will dramatically reduce vehicular emissions associated with the project allowing the City and County to reach their carbon neutrality goals within the decade despite the additional of 14,000+ vehicular trips per day associated with the project. This is an unsubstantiated and misleading claim.

Despite advances in battery storage capacity and decreased cost, the overwhelming majority of drivers still rely on fossil fuels to power their vehicles and will likely do so for decades. Of course, electric cars are the future and I’m not arguing that point. They emit no greenhouse gases and air pollutants compared to gasoline or diesel-powered vehicles and the life-cycle costs of operating such vehicles are compelling even now. And governments around the world are pushing for this switch.

But the truth is that electric vehicles won’t replace pollution-producing gas-guzzling vehicles for a long time. The number varies, but the U.S. vehicle fleet turns over about 7% per year. That means it would take about 15 years to replace all the vehicles on the road today. So even if every single car owner swapped out his or her gas- or diesel burning vehicle for a new electric model, it would take at least that long for the vast majority of vehicles on the road to be all-electric.

But electric cars are nowhere close to 100% of new cars sold. Currently, they account for only about 2% of new vehicle sales. Electric vehicles’ market share will increase, of course. One optimistic set of projections puts electric vehicle sales at about 50% of the market in California by 2030 and 90% by 2040. But even with a 50% new electric vehicle market share by 2030 and a 90% market share by 2040, it would take until mid 2039 to get us to where 50% of the vehicles on the road would be electric and until 2047 for 90% of all vehicles on the road to be electric(see attached Appendix A). According to the recent UN Report on Climate Change, we will have by then already far surpassed the goal of limiting planetary temperature increases to 1.5° C and it’s game over for the planet as we know it.

Conclusions

Despite the hyperbole from DISC proponents, the facts belie their rosy projections of reduced congestion on I-80 and local roadways resulting from the proposed I-80 freeway expansion. If VMTs are substantially increased as a result of the planned expansion of I-80 through the addition of HOV lanes as proposed, there will be little to no reduction of congestion on I-80 and the DISC project can be expected to substantially increase the congestion on Mace and Covell Blvd. by almost 12,000 vehicular trips per day further exacerbating an already unacceptable traffic condition. This congestion will be occurring far into the future even if the majority of commuters elect to use public transit to get to the DISC complex.

Further, if adoption and use of electric vehicles occur at projected rates and as many as 50% of commuters eventually elect to use public transit (an exceedingly highly optimistic and probably unattainable objective), substantial increases in Davis’ GHG emissions from fossil fuel burning vehicles will still be occurring at least through the early 2040s.

The only logical choice to limit future traffic congestion and GHG emissions resulting from the DISC project is thus to deny build-out of the DISC project until stringent and enforceable limits on single occupancy vehicle (SOV) traffic are  acheived – particularly by non-electric, fossil-fuel-powered vehicles. The potential future failure of the City to impose such restrictions on this project would be a de facto renunciation of their very own Emergency Climate Resolution calling for carbon neutrality by 2040.

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12 thoughts on “Guest Commentary: DISC Traffic Problems and Associated Vehicular Emissions Will not Be Solved by the Proposed I-80 HOV Lane Expansion”

  1. Craig Ross

    Who needs professional traffic analysis when you have Alan Pryor.  BTW, as I understand it, proponents are not relying on the freeway fixes that are at least ten years off, someone showed me pretty elaborate Mace reconfiguration which should at the very least allow local traffic to have a path through the overpass.

    1. Alan Miller

      Who needs professional traffic analysis when you have Alan Pryor.

      I guess you’ve never heard of consultants and their tendency to produce what the person who hires them wants to hear?

      pretty elaborate Mace reconfiguration which should at the very least allow local traffic to have a path through the overpass

      I’m not familiar with the design.  Do tell.

      Where’s the ped/bike underpass this time around?

      1. Bill Marshall

        Where’s the ped/bike underpass this time around?

        Appears, there isn’t…

        Here, Alan M, am in full agreement (I think) … there needs to be a grade separated bike/ped facility @ N end of project/existing Mace Ranch, with connection to N/S bike-ped path farther west… the sooner that gets into ‘base-line’ feature, the better, for a positive vote… including mine… it’s too damn logical…

        1. Bill Marshall

          There may be some nuances in why we agree… it is not my “litmus test” but close to that… I see it as a way to minimize traffic in Mace Ranch for employees… I also see that the residential component might generate (pun semi-intended) kids… with a pretty good shot to the elementary school and the JrHigh…

          And, it is probably ‘our’ last, best, chance to have a grade-separated crossing of major arterial… any future development to the north, or northwest should be required to reimburse the proposed project on a pro-rata basis…

          That is possible with a Development Agreement, and the will of current/future City Councils… adjacent properties should be given a “credit” for any right of way, etc., they bring forward… in the here and now…

          But if the project is approved, and if the crossing isn’t done, a door will be closed, and unlikely a window will be opened in the future… I believe that the area under the Covell/Mace curve WILL be developed, tho’ perhaps not in my lifetime… that, too, is logical… I feel this is the developer’s and the City’s only time “at bat” to get it done.

  2. Todd Edelman

    I’m not familiar with the design.  Do tell.

    I also have no idea what he is talking about.

    Where’s the ped/bike underpass this time around?

    They very well may implement a standard crossing of an arterial at the two planned egress points on Macovell Surface Freeway. They will likely claim that the plan “reduced size” project doesn’t warrant that, even if it’s access for Harper Junior because only cruel and stupid parents will move their kids to the new NE corner of Davis (West West Sacramento). Or there simply won’t be enough kids.

    Also from I can grok they are planning for vehicles approaching from the east to use Count(r)y Road 32A’s exit east of Mace, and likely use the same to head West, and 32B to head back east. This is so convenient and makes it very easy for people living and working here at Wannsee Conference (following nature theme of Bretton Woods) to completely avoid knowing anyone in Davis or do anything here. Note that these roads are not really intended for this type of use, and that anything but a fully-protected bike lane on this route will not be safe.

    Congestion won’t be reduced at Mace as much as spread everywhere.

    But aside from my fellow Commission-exile Pryor’s excellent take down of the Miracle of Freeway Expansion and Electrification, it is simply difficult to impossible to conveniently and/or safely get to a wide variety of places from Wannsee by bicycle, even fast e-bikes, by people of all ages, and it’s so peripheral that only a very small proportion of Davisites are close enough to want to come by bike to work here or visit friends.

    As you can see also from the not-so-technical concept the internal streets are ridiculously wide.

    If SACOG, the County and the City were smart they would have eliminated the chance of this going forward in any form many years ago, and instead pushed for many small developments in brownfield areas adjacent to I-80 – and unsuitable for housing and parking lots closer to Downtown – connected by inexpensive autonomous EV shuttles on fixed routes and perhaps two new bike/ped connections across I-80 – these solutions to provide equal connectivity to a bunch of complementary facilities in the same location for any business synergies that actually happen.

    Better would be to re-locate, bury or enclose I-80, but we’re going to do that in the General Plan, and SACOG, the County and the City are also going to sue the State and Federal Government to pay for that and rapidly optimize the passenger rail corridor currently used by Capitol Corridor as a guest.

    1. Ron Oertel

      only cruel and stupid parents will move their kids to the new NE corner of Davis (West West Sacramento).

      I believe you’re referring to “East East Davis”.

  3. Keith Y Echols

    , it is simply difficult to impossible to conveniently and/or safely get to a wide variety of places from Wannsee by bicycle, even fast e-bikes, by people of all ages, and it’s so peripheral that only a very small proportion of Davisites are close enough to want to come by bike to work here or visit friends.

    Yes, this is likely true.  In theory those homes are there to best serve those that work at the center…so less of a commute issue.  Others that live there will probably likely be ones that commute to Sacramento…so bicycle commute issues aren’t as significant.  But well planned expansion of the community should include planned supporting neighborhood retail to service the immediate area.   Ideally this should exist (better than it does currently in the form of single story strip malls) for existing neighborhoods too.

    As you can see also from the not-so-technical concept the internal streets are ridiculously wide.

    Don’t you need ridiculously wide streets for bicycle lanes?  Also, those streets are serving traffic coming and going to a busy business park….so high capacity interior roads are necessary?

    If SACOG, the County and the City were smart they would have eliminated the chance of this going forward in any form many years ago, and instead pushed for many small developments in brownfield areas adjacent to I-80 – and unsuitable for housing and parking lots closer to Downtown – connected by inexpensive autonomous EV shuttles on fixed routes and perhaps two new bike/ped connections across I-80 – these solutions to provide equal connectivity to a bunch of complementary facilities in the same location for any business synergies that actually happen.

    I’m not sure what you mean.  But much of this sounds unrealistic and therefore shouldn’t impede progress or at least be a consideration in deciding future growth and expansion.  Maybe if you better explained your comment, I might consider it.

     

  4. larryguenther

    The entire presentation of the project and explanations of how traffic will be mitigated show quite clearly that this project is being designed around commuters.

    Approximately three quarters of our environmental impact comes from vehicles, not buildings: i.e. driving, not living. Approving commuter-centric development after making a climate emergency resolution does not make any sense if there was any integrity in that resolution.

    And adding lanes to reduce traffic is like loosening your belt to cure obesity.

    1. Don Shor

      And adding lanes to reduce traffic is like loosening your belt to cure obesity.

      The purpose of adding lanes to I-80, particularly lanes that favor vehicles with multiple occupancy, is to make traffic flow more smoothly and reduce congestion. Failing to expand road capacity to meet increased demand from increased population is like making a 16-year old keep wearing the pants he had to wear when he was 8.
      Forced scarcity doesn’t achieve better transportation.

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