In an earlier post, I laid out my plans for creating a road trip map across all the major US Highways. I discussed how I set up the network and the algorithm I used to find the path. In this post, I’ll show you the resulting paths I found and how I narrowed in on my ultimate road trip.
Before making my first run of the search algorithm, I made a quick summary of my network to see if there were any additional constraints I could add to help find a path. Turns out, there were a few:
After carefully putting these constraints into my algorithm, I decided to start the path with Hwy 46 and run the algorithm. There were a few highways left out, so I used Method 1 of the Filling the Gap methods to fit them back in (the “graft and retry” approach). After three retries …success!! Figure 1 shows the raw output of this first attempt.
Figure 1: Raw output of first attemptThis was a bit too clunky for my taste, so I went in and, with some friendly assistance from Google Maps, filled in some of the lines with extra points to add a bit more curvature and follow the actual route more closely. I also added in a Marker Type column to my data, which I could use to identify major cities and landmarks along my path. To keep from crowding the graph with too many markers, I copied the Latitude column, deleted the values in that column that were not associated with a major city or landmark, and then made the points use that column as its “Y-axis” (you can do this by selecting the Variables arrow under the appropriate group in JMP Graph Builder). By the way, the background maps I’m using here are Street Map view with the US states imposed (the border lines are set to a slightly darker grey than the default).
After this bit of tidying up, I get the path shown in Figure 2.
Figure 2: Cleaned version of first attempt
I can imagine some of your responses to this map being among the following:
OK, OK, so I admit there are quite a few issues with that first attempt. The most notable for me was the fact that it missed several states completely, which certainly would not do for a road trip across the country (sorry, Alaska and Hawaii; I hope you understand). So why were these states being left out? Well, to answer that question, I did what I should have done in the first place: plot the network!!
Figure 3 shows the highway network I compiled as described in the previous post.
Figure 3: The highway intersection network visualized
From this figure, we can clearly see why those states were missed.
With the information gleaned from Figure 3 in hand, it was time to add in a few more constraints to ensure that every state was visited and sufficiently so.
With these new constraints added, I re-ran the algorithm and had only one highway left out. So I used Method 2 of the Fill the Gap methods to add it back in (the “try every option” method). After some cleaning, this resulted in the map shown in Figure 4.
Figure 4: The second attempt at a road tripWell, at least every state has some coverage now, though it is still a bit messy. One thing I still wasn’t too keen on with this trip is the loop there in Wyoming. It turns out that Hwys 87 and 85 run pretty much concurrently with I-25 from Denver down, which is why they show up the way they do here. Also, it looks like Washington state gets hardly any coverage, as does Vermont. So I added a few more constraints (including switching to a Hwy 101 – Hwy 12 start) and got the path shown in Figure 5.
Figure 5: Yet another attempt at a road tripLooking a bit better now. Still a lot of overlapping with some parts of the path, but not as bad as the round 2 version, in my opinion.
So it seems I was able to address the “missing states” problem with these last two paths. However, there is still quite a bit of craziness going on in the layout. It feels like this post has run its course, so in the next one, I’ll discuss some adjustments I made to try and clean up the path further and show my final path.
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