The Law of Averages
There’s a joke about economists in a bar talking about their net worth. Each one is proudly talking about how much they have and when they get to the last person to speak, he breaks out into a big smile. Asked why, he points behind the other and says “Bill Gates just walked in, our average network just went up 10,000%.”
About a year ago, the Harbor Bay Village VI project EIR came to the Transportation Commision. This is the project which has applied for some of the business park to be re-zoned. It’s a complicated project (unless you just say no to everything, then it’s easy), but that’s another discussion for another day.
One of the questions/comments (Question 5.13) made by the commission was how the EIR could show a reduction in traffic delay at some despite an acknowledgement that traffic at that intersection will increase.
The response is rather astounding:
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It is possible to add Project traffic to an intersection approach with existing low delays, with results showing reductions in average delay at the intersection. This tends to occur when the majority of future traffic is added to through movements that have minimal delay, thereby reducing the overall average delay at the intersection. The traffic study show that reductions in the overall intersection delay does not necessarily translate into reduction of delays to all approaches. However, the operational analyses provide sufficient evidence that the Project would not result in any substantial changes to future traffic conditions in the area.
First off, it highlights a flaw (minor possibly) in the overall methodology of calculating the traffic impact of projects. (This is separate from the major flaw in our EIRs which only look at certain types of impacts like intersection congestion, as opposed to travel time, but again, story for another day). The idea that we can add traffic to an intersection and increase the efficiency (keep in mind the EIR isn’t proposing any changes to the intersection before making this finding, first it makes the finding, then it proposes mitigations, if necessary, to alleviate problem spots).
To my untrained brain, I would think that a finding of “we’re putting more traffic into an intersection and it’s going to reduce congestion” would trigger a solution of “we need to look at this and re-jigger our analysis to clarify what it says.”
The amount of traffic being projected by this project is really small (which isn’t an endorsement, just an observation) and so the impacts are likely to be small. BUT, if the EIR doesn’t identify real impacts, there is no mechanism for the city to require mitigations.
Enjoy your weekend!
delmundo
May 9th, 2008 at 9:36 am
That response is a word that should not be used in print. (It comes out of the south end of a bull walking north)
David Kirwin
May 10th, 2008 at 9:12 am
“The amount of traffic being projected by this project is really small”
JKW - This is only your subjective analysis. I would say it is as flawed as the faux scientific analysis that says more traffic at an intersection will improve “level of service’ for that intersection.
We know that this project is for 104 new homes, and for that new neighborhood everyone must use a single street to go there or to leave. It is only one way or the other on Harbor Bay Rd. Look at Cowan’s other developments - especially the most recent expansions out on Bay Farm, notice only well-to-do homes with an average of at least one car for every driver. Using common sense as required – how many vehicles per commute, per school drop-off, are to be added to the intersections examined? What will happen at all the other traffic areas not examined? What will all the new cars do at the elementary schools every morning? (I think some of the traffic studies were done when school traffic was not “in session”) What you call “small” is relative, and shows your bias. If the same # of car trips were to be added to your street I doubt you would still call it a “small” number, and it is likely that most will be using that portion of Island Drive that is already the 2nd most congested stretch of roadway in the entire city. That statistic is by the traffic study used by the traffic Commission you chair, it would be wrong of you to deny the facts.
You point out the flawed methodology; I still wonder what exactly they are talking about. I have not had time to read the final EIR, but I noticed my letters were not included. Perhaps if all the given traffic leaving the projected new development heading toward the south bay used the cross-airport ‘Cowan expressway’ and were not required to stop and wait for the traffic light to change at Harbor Bay and Cowan, this would lower the overall avg delay at the traffic light. The other example I can think of is when the rest of the traffic goes the other way on Harbor Bay to use McCartney as their ‘rabbit trail’ off the island.. If you only examine what happens if the new neighborhood uses Ratto Rd to Aughinbaugh and makes a right on red to McCartney, then by their system of abusing data to create a false perception, the average delay MAY seem decreased. At the traffic light at McCartney / Aughinbaugh. Does this about sum up your understanding as well?