April 10


The April 2014 ITE Journal presents research by Gunn, George, Holcomb, Bekele, Ardeshiri, and Zheng related to how much traffic is generated by a Consolidated Rental Car Facility at the Thurgood Marshall International Airport in Baltimore, Maryland.  The article is well written.

Tangent – wait for it, wait for it…. Consolidated Rental Car Facilities at Commercial Airports = CRCF.  Another acronym!

The article presents three weeks of traffic generation data from the busy season at the airport (July 23, 2012 through August 5, 2012).  The authors also states flight data has been consistent from 2000 to 2011.    The data was pretty consistent over the three weeks, but obviously you should be cautious about applying data from a single site to any other site.

Here’s the background data on the site:

  • Facility’s used by multiple rental car facilities.
  • 8,000 parking space garage complex.
  • Maintenance and service facilities on site.
  • 47,000 square foot customer service building.
  • Strong correlation between daily passengers at the airport and the rental car facility trip generation.
  • Poor correlation between rental car facility trip generation and employees or square footage of customer service building.

And here’s the trip generation data from the article:

Trip Gen Table

Some thoughts about the data:

  • They have 8,000 parking spaces with 6,000 vehicles entering then exiting on an average weekday.   It isn’t mentioned if the trip generation is constrained by a limited amount of available rental cars.
  • Parking generation data isn’t supplied.  With 8,000 spots turning over 6,000 vehicles, my gut reaction is that there are a lot of spaces sitting empty at any given time.  Sunday turnover is about 4,300 rental cars – about 2,000 less than on a weekday.  Still, there could be a lot of empty parking spaces even on Sunday.  Last I checked, parking ramps cost about $10,000 per space to build.  Rightsizing the number of parking spaces is hugely important in my mind.
  • This data is from 2012.  Several car sharing programs targeting airports have popped up (RelayRides, FlightCar and ZipCar to name a few).  These schemes probably don’t reduce trip generation very much because the owners driving to/from the airport and then renters driving to/from doesn’t actually change the overall trip generation compared to the rental being a traditional one, but the onsite parking of airline passengers is significantly reduced.
  • Peak hour trip generation is based on the daily air passengers.  I wonder if the data could be sliced and diced to come up with the peak hour air passengers.  My hunch is that peak hour air passenger data would provide a stronger correlation with peak hour rental car trip generation.
  • The airport has light rail and Amtrack along with just about every other ground transport option.  The popularity of all of the other modes besides the rental cars probably plays a part in the rental car usage.  It may be to complicated of a system to untangle, but all of that other data could be useful when trying to apply the trip generation rates from this airport to other airports.
  • Overall – I always want more data!  But this is a helpful data set for those working on airport traffic modeling.
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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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