It can be very empowering and exhilarating to make your own PRT designs for where you live, work and play. It allows you to see the exciting possibilities for PRT as well as the costs and realities. It also can give you a plan so that you can talk to your local officials and get them thinking about PRT in your community. This page is an attempt to get you started on that process.

Basics of PRT layout

PRT is basically a network of one way non stop routes so you have to think in a way that optimizes this principle into a workable design. The principles that you want to maximize in a PRT network is that you want to 

• equalize the trip length from any given point to any given point in the network as much as possible. This is so that going from point A to point B is a similar trip length as going from point B to point A (as much as possible).
• minimize bottlenecks in the system so that "traffic jams" (PRT vehicles waiting to merge with other PRT vehicles) are minimized.

 The simplest PRT design and the basis for all other designs is the loop.

If the loop is small enough, then trips from point A to B will be short rides as will rides from point B to point A. If for example it takes 3 minutes to traverse the loop and the shortest trip between stations is 30 seconds then the difference between the shortest ride (30 seconds) and the longest (2 minutes and 30 seconds) would be two minutes. That is a perfectly acceptable variance. If on the other hand it took fifteen minutes to traverse the loop and the shortest ride was still 30 seconds, then the difference between the shortest and longest rides would be 14 minutes. This would be unacceptable (for me) for you could probably just walk back to point A as quickly as ride. 

If you need to cover a larger area, instead of enlarging the loop, you could instead add another loop and connect the two. 

If you compare a one loop design to a two loop design that covers the same area, you would see that the two loop system reduces average trip times from every station to other station in the system. Below are two layouts (two interconnected loops and one large loop) each with 8 stations.  Below that is a table that compares trip times for each layout. The tables assume that the trip from one station to the next takes one minute on the single loop. Also trips on the double loop from adjacent stations on different loops are assumed to take two minutes (e.g. from D to E).

Expanding the design further, more loops can be added so that in the following design, you can see the idea of alternating clockwise and counter-clockwise loops. The inner loop's traffic goes counter-clockwise and the outer loops' traffic all go clockwise.

Beyond that you can create a large outer loop (around the entire network) by connecting up all the outer loops again.

So you can see in this way the system can be built to more and more loops joined in alternating rotations to cover an entire city. Also an outer loop could be added to this design as well.

Station Design

Get a map

The next step with making a PRT layout is to get a map so that you can apply the above principles to it. You can take a regular paper map (of the street level variety preferably) or you can take get a map off the one of the free internet mapping services on the web like Yahoo Maps or Mapquest. With the mapping services, you will probably have to get a map of an area several times and "stitch" the maps together to form a larger map. I'll show you how to do that later.

Splicing an Internet Map

If you are running in Windows, you can follow these instructions exactly. If you are not, there are ways in Linux and on the Mac which are similar (I will provide instructions when I get a chance to or if someone provides me with some - hint, hint).

1. Go to a map site and get a zoomed out view of the area you want to map
2. Zoom in to one corner of the area to the street level
3. Press Ctrl-Alt-Print Screen (this should copy the screen contents to the clipboard)
4. Run the built in paint program (ie Programs | Accessories | Paint)
5. Go to the edit menu and Paste the image in
6. Use the marquee tool to select just the map portion of the screen
7. Select Edit | Copy
8. Do File | New
9. Select Edit | Paste
10. Do File | Save to save that segment of the map
11. Go back to step 2 and zoom in on another section of the map area
12. Do the above until you have all the map segments saved
13. Run Paint again
14. Go to Image | Attributes dialog and make the canvas large enough to hold all the segments (just make it very large to start with)
15. Run another copy of the Paint program
16. Open up a map segment
17. Select the whole map (by Edit | Select All)
18. Copy it (by Edit | Copy)
19. Paste it into the other Paint program into its appropriate place, lining it up as necessary
20. Once the image is all pasted together save it to disk.

Whew, that was a lot of work wasn't it? Now print out your map so you can go on to the next step.

Laying out the network

Now that you have your map either printed out or you have a paper map start by locating where your loops will go. Keep in mind some of the advantages of PRT when thinking about how this will interact with existing structures:

• Stations can be inside of buildings (they don't have to be out in the cold and rain)
• In an area with more than one building or mall, remember that they were designed so that their parking lots have to hold the maximum number of cars that they ever expect to get but not what they get on average, because sharing parking space between buildings is not practical (the walk is too long). PRT allows interconnected buildings to share parking space thus possibly reducing the amount of land devoted to parking space to be reduced (perhaps allowing more green space or other uses).
• PRT can run above ground, at ground level or underground if need be.
• Stations can be larger or smaller as traffic patterns require. If it is next to a stadium, then a large amount of people will need to be moved at once so one large station (many berths) or several medium size stations should be used.

Costs

When costing the network try using the following parameters

• 6 million a mile of one-way track
• 0.7 million per station

Conclusions

Have fun with this and when you are done, send it to us and we will post your vision so that it can be shared and inspire others!