My View: The Proposed Fixes by Caltrans May Not Correct Traffic Problems in Davis

On Thursday Caltrans had an open house to discuss proposed fixes to the freeway.  While the format of the meeting was less than desirable, the solution they offer does not appear to address the major problem along this corridor.

First, at Kidwell, they propose converting one mixed-flow lane to managed lanes.  Then at the Solano/Yolo County line, all the way to the Yolo Causeway, they propose paving the median and adding a managed lane.

Finally, at the Causeway they propose adding managed lanes there as well, while moving the existing bike path and creating a separate bridge.

A lot of people are skeptical that simply adding traffic lanes – ten years down the line – is going to fix the problem.

Especially when the problem appears to occur due to two key factors – the increase of lanes to six and back down to three over a relatively short period creating a bottleneck that many vehicles attempt to bypass by using local roads, which in turn creates not only local traffic jams in places like Davis, but also probably contributes to the slowdown as all of the vehicles re-converge at the entrance to the Causeway.

We can see this analysis in the two presentations made by Fehr & Peers discussing Mace.

As Adrian Engel from Fehr & Peers discussed in his presentation on Tuesday, there is a direct correlation between freeway speed and the traffic that diverts onto side streets, with most of it entering onto northbound Mace and reentering the freeway around Mace.

Mr. Engel actually noted that the biggest advantage in terms of time is not to take the Dixon bypass at Tremont, but rather to go to Highway 113 and cut across via Road 29.

He explained that he and his team got onto the freeway during peak time to validate that the freeway was not the fastest way to get from Dixon to the Causeway. Five of them traveled at the same time through different routes to see if the apps and maps and Waze “were telling us the true story.”

Traveling on the freeway was indeed the longest time. Some of the other routes “were definitely faster than the freeway.” The fastest they found was Highway 113 and County Road 29 to bypass the queue. They found that to be almost 15 minutes faster.

“There are multiple ways that can be used to bypass this freeway traffic,” he said. “The software that’s giving you these alternate routes is true and we have verified are actually faster. Ultimately the solution for this problem is going to fix I-80 and getting that traffic to flow better to keep cars on the freeway. Because if you fix Mace or do something to Mace, it may just cause traffic to go in other places.”

Ultimately, he said “the solution is to fix I-80 and get the traffic to flow better.”

Caltrans acknowledged the same problem in a September 23 letter to Bob Clarke, the city’s Public Works Director.

Brian Alconcel, Caltrans District 3, Chief Traffic Operations notes:  “The severe congestion on EB I-80 and the use of GPS navigation apps have allowed drivers to make real time route changes based on travel times.”

He notes that that traffic is utilizing two primary routes.  The first is exiting at Pedrick and traveling to Tremont and then County Road 104 which becomes Mace.  The second exits at 113 and uses Covell Blvd. to get back on the freeway at Mace Blvd. by the southbound Mace exit.

Mr. Alconcel writes: “Travel times on the local road routes were faster for almost all time periods during the PM peak period, making the local road routes more attractive options for travelers.”

Why are they finding the traffic is primarily getting off I-80 at Dixon?  The problem here, as Mr. Engel explained at the October 24 meeting at Pioneer Elementary, has to do with the configuration of I-80 as you hit UC Davis and it goes from three lanes to six lanes but then it condenses back to three lanes by the time you hit Richards Blvd.

That creates a huge slow down which traffic is trying to bypass out of.  There is a second bottleneck at the Causeway – but you can’t bypass out of that one.  So basically what Fehr & Peers found is that by bypassing at Tremont, you save 10 minutes, and apparently going 113 to Road 29 and reentering near the levee off Road 32, you end up saving 15 minutes.

But you’re only bypassing the traffic jam at UC Davis.

The way the freeway works is that you hit the bottleneck on eastbound I-80 right after the UC Davis entrance and that continues to Richards.  It then runs at three lanes the rest of the way, but there is a secondary bottleneck, depending on the day, starting around Mace and going through the Causeway.

If you stay on the freeway, you hit the bottleneck in two locations, but even if you bypass the queue at Dixon or 113, you will hit a back up attempting to get back on the freeway, whether it be at Mace or near the fruit stand near the levee, and the traffic remains slow until you are a good way across the Causeway.

Are adding managed lanes and increasing capacity going to fix this problem?  I think a lot of people are justifiably skeptical on that.  The other question is why there is a need to increase the number of lanes to six at that point in the first place?  Re-configuring the Highway 113 and UC Davis interchanges may make a lot more sense than simply adding managed lanes.

Interestingly enough, Caltrans has data which shows that by putting the metering in at Mace, they have helped to alleviate the congestion at the Causeway, but it has apparently come at the expense of local traffic congestion in Davis.

Note, however, that in both cases the traffic congestion begins when I-80 drops from six lanes to three just after UC Davis.

—David M. Greenwald reporting

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About The Author

David Greenwald is the founder, editor, and executive director of the Davis Vanguard. He founded the Vanguard in 2006. David Greenwald moved to Davis in 1996 to attend Graduate School at UC Davis in Political Science. He lives in South Davis with his wife Cecilia Escamilla Greenwald and three children.

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  1. Todd Edelman

    The best transportation systems can do no more than partly mitigate poor development choices. This destructive and time-wasting crisis has been brought about by the extremes of greed and narcissism, primarily in the western area of the Northern California Megaregion, enabled by a continued lack of robust regional think-space, accountable to the citizens… and with teeth.

    Only the western area, administrated the Metropolitan Transportation Commission, has started to make some reasonable moves on a mobility fix, but it’s marginal at best due to lack of funding and will, and continued economic displacement from west to east.

    Alternative no. 5 in the Caltrans plan – none of the presentation is yet on their website because it’s likely not required to be there –  prioritizes transit in the creation of new lanes. Combined with an amazing bicycle facility between east Davis to West Sacramento that similarly prioritizes the use of fast e-bikes (Type 3 by state definition, with assistance to 28 mph) this Alternative will cost hundreds of millions and will – at best – dull the venom-coated blade of criminally-stupid bad development for the section of I-80 in close proximity to Davis. I-80 will still be noisy and many other bad things.

    The best fix focused mainly on transportation-based solutions is to have 75 minute train services from Sacramento to the SF Financial District leaving every 20 minutes during commute hours, combined with a European-style ring road, bypass etc of I-80 around the City, starting somewhere between 113 and Dixon, south of Putah Creek and then up to the west side of the Yolo Bypass. The latter will make the general center of the City a much more livable space, and the sales of land for re-development in this corridor between 113 and the Bypass will help finance the ring road. Still, this will also cost many billions of dollars from other sources, and there’s no guarantee that the people who live in the large new area will work locally, and there’s no way to ensure that most who work there live locally.

  2. Bill Marshall

    Here’s a  (cynical, but may have merit) thought… or two…

    Try a road diet on I-80… “worked” on Fifth Street, right?

    Instead of viewing it as a “problem”, consider it the ‘new normal’… then, it’s not a ‘problem’…

    Expectations, and behaviors are the ‘root cause’… and there are real costs (or “costs”) to try to satisfy expectations, change behaviors… I-80 and Mace have plenty of capacity… if expectations and behaviors change… ~ 16 hours a day (2/3 of the day), no congestion (unless there is a crash, usually resulting from a “stupid”… another set of behaviors) exists.

  3. Ron Oertel

    From article:  “The second exits at 113 and uses Covell Blvd. to get back on the freeway at Mace Blvd. by the southbound Mace exit.”

    Probably don’t need me to remind everyone, regarding the site of the ARC proposal along this route.  Either that, or they’ll (also) be sharing the freeway access point right before the Causeway.

    No to mention the commuters back the other way from ARC, toward Woodland (along Road 102).

      1. Rik Keller

        In comments on yesterday’s article, Ron O. asked: “Hmm.  I “wonder” where that traffic ends up?  Perhaps going right past a site proposed for a 4,340-parking space development?”

        And Greenwald answered “No. Actually it ends up entering off Road 32 right before the causeway.”

        But then we find out today that Brian Alconcel, Caltrans District 3, Chief Traffic Operations stated  that “traffic is utilizing two primary routes.  The first is exiting at Pedrick and traveling to Tremont and then County Road 104 which becomes Mace.  The second exits at 113 and uses Covell Blvd. to get back on the freeway at Mace Blvd. by the southbound Mace exit.”
        So, “actually” Greenwald’s definitive “no” answer is completely contradicted by Caltrans.

    1. Rik Keller

      Ron O.: it’s a good reminder, especially with Greenwald trying to latch onto the implication yesterday that ARC traffic would just bypass Mace altogether and not contribute to the “mess” there.

      On certain days, I have observed that app-directed bypassers have ended up in massively long backups eastbound on 32A itself (on the north side of I-80). This the traffic that diverted to 113 and then Covell and Mace (and some that is coming down south from CR105 from CR28H).


      1. Ron Oertel

        Thanks, Rik.

        I understand that there’s only one entrance to eastbound I-80 at the fruit stand, and that this is also often used by those coming from the south (“Mace Mess”) side, as well.

        Therefore, the traffic that’s being directed up Highway 113 to Road 29 will mix with ARC traffic, as well as the “Mace Mess” traffic.

        In addition, there will be additional traffic going up Road 102 (toward Woodland) from ARC, which will make it that much more difficult for those same folks being directed to Highway 113 and Road 29, since they would have to cross Road 102 (to reach the road that goes by the landfill).

        More dangerous, as well – as folks become impatient for a break in traffic, to cross Road 102.
        (Which is already a problem.)

      2. Ron Oertel

        To clarify, the fruit stand that I (and apparently David) are referring to is the one right before the Causeway.

        Truth be told, I don’t think that ARC will be approved, based upon the traffic problems (alone). I’d suggest that the developer just save his money (and others a lot of grief and expense), regarding the planned campaign.

        Farming is a noble and needed service, as well.

  4. Rik Keller

    The article states “Note, however, that in both cases the traffic congestion begins when I-80 drops from six lanes to three just after UC Davis.“

    There are two senses of the word “begins” in that sentence. The first is that is the location where eastbound traffic first experiences a slowdown. That is clear, at least at certain times of day.

    However, Greenwald also stated in comments  yesterday that “I don’t understand why they aren’t fixing the real problem – the six lanes to three lane merge, they need to fix that.  This doesn’t…. The Causeway problem is secondary to this one.”

    So the second meaning that is implied by “begins” is more expanded: that this area is the primary cause of the traffic backup. There is no data or evidence presented here to indicate that this is the case. And adding an additional lane in that stretch would seem to be addressing the 6 to 3 to 6 situation partially anyway (unless they are expanding to 7 temporarily also).

    It could be the case that the Hey 113 area is just the furthest eastward extent that traffic backs up to when it starts to get congested at the Causeway and not actually the “primary” cause of the congestion in the first place. Determining that would require looking at the data, rather than just making unsupported pronouncements like Greenwald is doing


    1. Darell Dickey

      HI Rik,

      There is plenty of evidence to suggest that the bubble is what initiates the domino effect of much of the congestion we see. Eliminating the bubble won’t fix everything, but all evidence that I have points to the bubble being a significant contributing factor. Traffic is an amazingly complex thing. But just like one fender bender can bring an entire freeway to a crawl (both ways, even!) is indication enough that adding one bit of friction to the system can stuff the whole thing in minutes. The frictional merges created by the bubble is that thing we can fix easily. It would be like taking one crash out of the commute. I attempted to explain the bubble’s negative effect in the previous comment thread on the “Caltrans Hosts Open House” article. I have to get off the forums and onto my life now!


      1. Rik Keller

        Darrell: thanks! I replied on that other article thread in more detail . Short response here: I have not seen any evidence that the “bubble” “initiates” the congestion that occurs further down-road around Mace and the Causeway.If you have some, it would be interesting to see.

        Sounds like you have a good plan fir your day!



      2. Rik Keller

        As a follow-up and reality check, I looked at Google Maps data showing typical traffic patterns by day of the week. I examined these for Monday through Friday afternoons in 10-15 minute increments, and–sure enough–the first traffic slowdowns are right at Mace, followed shortly thereafter at the bubble (on some days these arise simultaneously), and then filling in between the two areas shortly after that. There is no “domino effect” of the bubble initiating the traffic slowdowns forward to Mace. And there is no sense in which the “bubble” slowdown could be said to be the “real problem” and the “primary problem” compared to the Mace/Causeway area as Greenwald claims.

    2. Rik Keller

      It should also be noted, that according to Google Maps “typical traffic” data, southboand Mace north of I-80 and northbound Mace south of I-80 start to show traffic congestion (indicated in orange) at right around the same time Monday-Friday, and also start to show heavy congestion (indicated in red) right around the same time after that too. This starts to happen before there is congestion shown on I-80, and thus would not appear to be driven at least initially by app-following shortcutters.

      1. Darell Dickey

        Thanks for all the study and input, Rik. I’ll check the other thread too. It could well be that my  experience/info/study is now out-dated. I think we can all agree that our traffic issues have changed dramatically in the past few years. And I have a total WAG to continue to support my claim: Perhaps now that folks have experienced the bubble issue for some years, they aren’t first waiting for it to form before diverting. They might instead be bypassing the freeway as a matter of course, thus starting the problem closer to the causeway.  :shrug: If this is true, I’m still happy to continue blaming the bubble!

        The part of this that I still regularly experience is the bubble stop-and-go followed by the release to effectively “free-flowing” immediately after. In some measure, I have experienced this oddness for at least the past 15 years. And that the traffic EVER starts moving again after the bubble is tough to pin on anything BUT the bubble. (some have suggested the cars joining from 113 and Old Davis are causing the issue… but those are so few that it is barely a blip on the graph.) Very often, I-80 is flowing above the speed limit until the cars reach the widest point of I-80. At which point they stop… no matter how the traffic is flowing at Richards.

        1. Bill Marshall

          Am thinking the “bubble” metaphor is misleading, to an extent… although it is incorrect to draw too many parallels between fluid hydraulics and traffic flow, some pertain…

          In hydraulics, there are “losses” from sudden expansions and sudden contractions… another analogy might be a ‘funnel’… a lot of room to accept liquid one end, but then it backs up at the top, as the fluid flows out the lower orifice… but the flow rate, once it gets past the contraction (less merges/lane changes), it flows pretty well.  Often, barring collisions/crashes, the same is true at high volume times on I-80, both WB and EB… you go really slow from when I-80/50 merge, then you have Harbor, W Capitol, etc., but once you get a bit downstream from that, vehicle speeds get pretty normal… just like a funnel.  Until the next point where there are merges/lane changes…

          Just an observation over many years…

        2. Rik Keller


          I would just note a coupe of things in response to your anecdotal evidence.:

          1) if you are typically driving through the “bubble” when traffic starts to slow down, you would not know that it already started to slow  down a few miles up the road on Mace.

          2) the apps don’t pre-route people off of 80 before  a slowdown occurs resulting in slower travel times

          3) while traffic merging back onto 80 at Mace contributes to further congestion, this  is not the genesis of the congestion in the first place.

          Agaun, there is no evidence that the “bubble” is the “real problem” that Caltrans should be addressing.

  5. Rik Keller

    Let’s not forget that when Mace traffic concerns started to become a hot button issue earlier this year, Greenwald argued in April that we shouldn’t “allow our concerns about additional traffic impacts to drive our public policy…” regarding the MRIC/ARC research/office park (that hadn’t yet released its development proposal that point).

    He also said that “Clearly this project needs to be heavily transit-oriented to work…” It is not.

    And “any proposal is going to require a very good transportation plan and regional buy-in from SACOG (Sacramento Area Council of Governments) and other agencies to make it work.” It does not not have that. And the continuing worsening of congestion on I-80 will not be relieved by any of the proposed plans.


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