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OK, so I wrote about my experience at one of the vehicle emissions testing facilities here in the Chicago area.  I said I would share the findings of my mini-study of the location of these facilities with respect to population.

There are 14 testing facilities in the Chicago area.  Nine of them are full testing facilities that can administer the computer-based OBD system test and the exhaust-sniffing test.  Five of the facilities only administer the OBD test.  They also vary in the number of lanes they have, from three to six.  Theoretically, a facility with more lanes is more accessible, but I did not make any differentiation in the stations.  The same could be said about the accessibility of full-service stations, since they accommodate all vintages of cars.  However, I think most people have cars that are newer than 1996 and only need an OBD test.

To determine the accessibility of the testing stations, I divided the population of a census block by its distance from each testing station.  So a testing station close to a low-population block would have good accessibility because of its proximity.  On the other hand, a high-population census block farther away from the station may still result in the station having moderate to high accessibility.  The station is still being accessed by a large population, meaning it would still have decent accessibility despite being isolated from the population.

So here’s a map.  It shows population density (per square km) and the different testing stations.  The more accessible stations have bigger dots.  Only census blocks located in ZIP code areas that are required to submit to emissions testing are shown.

The testing stations tend not to coincide with high population density.  They are often located in industrial parks.  You can also see that some stations are clustered together and those on the outskirts of the testing area have lower accessibility.  Here is a table listing the facilities, their accessibility, and the size of the population they serve (adults 18+).

The most accessible stations were in high population areas – Chicago-Webster (highest), Chicago-Forest Preserve, and Skokie.  The stations with the lowest accessibility scores were Crystal Lake (lowest), Waukegan, and Joliet.

I made a map showing which station was closest to each census block.

At first glance, it would appear that there are too many stations in the northwest suburbs.  The Schaumburg, Elk Grove Village, and Addison stations are quite close to each other.  However, when you add up the adult population served by each station, they serve 346k, 228k, and 342k respectively.  The average adult population served by the 14 stations is about 416k.  So one could argue this area is being over-served by emissions stations.  The City of Chicago is served by five stations – Chicago-Forest Preserve, Chicago-Webster, Skokie, Markham, and Bedford Park.  The Bedford Park station is potentially the most overwhelmed in the system, serving over one million adults.  On the other hand, the Joliet station only serves 186k.  These adult population figures are based on the 2000 Census.

As you can see, the distribution of testing stations is less than optimal.  More stations are needed near Chicago, and the stations at the urban fringe need to be repositioned.  While a station is needed in the southwest suburbs, Joliet is not the right place.  Markham has its hands full, and Tinley Park is underutilized.  Likewise, both Crystal Lake and Waukegan are underutilized.

Here’s what I would do:

• Close the Joliet station
• Move the Naperville station to north Plainfield
• Move the Tinley Park station to Mokena or New Lenox
• Close both the Waukegan and Crystal Lake stations and open a new one in Volo.  Actually, there used to be one in Volo.
• Open a new station in South Elgin or St. Charles.  There used to be a station in South Elgin.
• Open a new station on the south side of Chicago to relieve the burden on Bedford Park.

Who is making these decisions to close emissions testing stations?  The contractor or the Illinois EPA?  Have they performed even the cursory analysis I have?  I can see on their website that four stations were closed in Chicago.  I already mentioned that stations in Volo and South Elgin would prove beneficial.  My proposal would help increase the utilization of each station, and provide better accessibility for residents.

Kane County has 262,741 adults in the testing area, yet there is not a single station in Kane County currently.  Residents have to travel far to the north, east, or southeast to get their vehicles tested.  Having a station in Kane would help serve the western end of the testing areas, and relieve the Schaumburg and Naperville stations.  If my plan were used, the loss of Crystal Lake wouldn’t matter because northern Kane residents would be better-served by a station in South Elgin or St. Charles anyway.

OK, I’m going to take a break and test my proposal to see if there is better accessibility and utilization.

[geognerd tests his proposal]

OK, I’m back.  My goal was to add a station to Chicago and even out facility utilization throughout the whole area.  In the end, I left nine stations intact – Bedford Park, Chicago-Forest Preserve, Lincolnshire, Markham, Schaumburg, Addison, Chicago-Webster, Elk Grove Village, and Skokie.  I reinstated the stations in Volo and South Elgin.  The Volo station replaced Crystal Lake and Waukegan.  The South Elgin station would serve Kane County as well as southern McHenry County, since they lost the Crystal Lake station.  I moved the Naperville station to Bolingbrook.  I also moved the Tinley Park station to Orland Park.  Lastly, I added a station to the south side of Chicago.

Here’s a map of my proposed network of emissions testing stations, along with the areas served by each station (closer to that station than any other).

And here is a table showing the utilization of my proposed facilities:

I figured the Volo and Lincolnshire stations could serve Lake and McHenry Counties.  However, I later found that 45-minute drive times existed in the Lincolnshire service area.  That isn’t really acceptable.  On the other hand, the Lincolnshire station would become better utilized, serving 433k people instead of 330k.  The Volo station had the lowest accessibility value.  It served 279k, but they were coming from all over the place, resulting in lower accessibility.  Also, that part of the metro area has a lower population density than elsewhere.

The South Elgin station only served 249k, which is less than I expected.  As you can see, it serves Kane County quite well, but its lower accessibility and smaller population make it harder to justify the location of that station.  But, it would be more accessible than Crystal Lake and would potentially serve more people.  Shifting the station south to St. Charles would help serve residents of Aurora, but at the cost of those in southern McHenry Co, which already has accessibility issues with the Volo station.

The Bolingbrook station surprised me.  This is a move of the Naperville station.  I originally intended to choose a site in Plainfield, which would be between the large cities of Aurora, Naperville, and Joliet, but I had a hard time finding an industrial park with vacant land.  These testing facilities tend to be in business or industrial parks, and Plainfield is a residential bedroom community that likely has a net out-migration during the day.  I found a site with a large lot in an industrial park in Bolingbrook.  I felt guilty about taking the station away from Joliet, so I also wanted to move the station away from Naperville and a little more toward Joliet.  The Bolingbrook station ended up having a huge service area, with an adult population of 504k.  Additionally, this is an area with a lot of businesses along Interstate 55.  This station could see a lot of traffic from workers in the area getting their emissions test done during their workday.  On the other hand, this is also an affluent area that would likely have a lower proportion of cars over four years old, which don’t need to be tested.  Lastly, this is a much larger lot than most testing stations are located on.  They could build the mother of emissions testing stations and could handle the workload.  It could accommodate a station larger than those in Chicago, which theoretically would have to handle more cars.

The Elk Grove Village station, which I left untouched, is in the large employment center of O’Hare Airport, which means it could experience heavy use during the workday.  For that reason, I left it alone.  This is the same thinking I used for the Bolingbrook location.

My next alteration was the move of a station from Tinley Park to Orland Park.  Not far from major roads and expressways, but it had a lower accessibility score and a smaller service population than the Tinley Park location.  To rectify this, another site like this one in New Lenox could be chosen.  It’s closer to Joliet, which would probably increase its accessibility and the size of the population served.  Markham could handle the extra few thousand people who would likely go to that station.  Choosing the New Lenox location would also take a small bite out of the Bolingbrook location.  My goal was to keep the population served to around 410k per station (which is the average), and Bolingbrook was over 500k, if you remember.

My final change was the addition of a testing station on the south side of Chicago.  I don’t know if this is a safe neighborhood or not, but it had a big old brownfield ready to be built on.  I was pleased that this station could serve 492k, and take some of the burden off the Bedford Park station.  Under my plan, Bedford Park would go from serving over a million adult residents to only 661k.  Who knows, maybe an emissions testing station on the South Side could provide construction jobs initially and a handful of jobs during the operation of the station.

So my proposal for a redistribution of emissions testing facilities has some positives and negatives.  Overall, there was only one station (Volo) that had low accessibility, and that was because it was serving a large, lower-population area.  My proposal would inconvenience northern suburban residents with longer drive times to reach testing facilities.  On the positive side of things, I showed a station in Chicago would be beneficial and the elimination of the Joliet station could be absorbed by testing stations in Bolingbrook and New Lenox/Orland Park.  The viability of the South Elgin station is debatable.

I know this was intensely dorky, but it was a fun exercise with real-world implications.  This is quite similar to an exercise I worked on with a couple of professors for an urban geography textbook.  I enjoyed getting to use my geography and GIS skills in this project, because I don’t get to do this stuff very often at my job anymore.  One would hope spatial analyses were performed when sites were selected for the emissions testing stations.  The operator of these stations have actual site visit data, which would be quite helpful in determining which stations were being used to their potential.  I tried to hit on site utilization when discussing Bolingbrook and Elk Grove Village.  Adult population is the closest proxy I had to determining how well-used a station would be.

Now for my next project – finishing up the maps of the 2010 General Election in November for IL governor, US Senator, and other stuff.

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