November 8


project-manager-made-mistakeSeveral years ago we did a traffic study for redeveloping a tired indoor shopping center.  The anchor grocery store was remodeling and there was about 40,000 square feet of vacant space inside because a couple of tenants had recently closed shop.  The new plan included developing small buildings on outlots around the mall in addition to revitalizing the mall itself – more of the modern approach (think of Walmart sites with outlot banks and fast food restaurants).

We did some follow-up work this summer that the city required.  Instead of a generic use on an outlot, the mall owner was working to get a McDonald’s with a full drive through.  The analysis from the summer showed the incremental change with McDonald’s was ok in the near term, but full redevelopment would require closing a median (full access becomes right-in/right-out) and putting a signal at their main driveway.

We’ve been hired for another iteration – instead of generic shopping center uses internal, they might have a mega-buffet taking up 15,000 of the vacant 40,000 square feet.

We started in on the process of updating our Vistro files and Max realized we double counted our pass-by trips in the analyses from this summer.  We over-counted by about 90 extra vehicles turning in and then out of the site in the full redevelopment p.m. peak hour.  Without the over counting, we didn’t need to close the median or put in the signal.  Ouch.

I should have caught this in my review.  This is one of the bigger (known) mistakes in my career.  What to do?

We talked through all of the options.  Of course it would be nice to bury a mistake, but this is always a bad policy.  The right thing to do is to correct the mistake and apologize.  And that’s what we did.

We updated our previous memo and actually spent a couple of days working on Vissim models to make sure no mitigation was necessary.  Then we sent the revised memo to the city for their file (along with several apologies).  Now on to the analysis for the mega-buffet.

I got lucky on this one since the mitigation we recommended was for a long term build out scenario.  It wasn’t being built as part of the approved McDonald’s.

It’s easy to let our guard down as the computer analysis software gets more powerful and more automated.  This experience reinforces that I need to triple check all of the numbers.





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Mike Spack

My mission is to help traffic engineers, transportation planners, and other transportation professionals improve our world.

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