This is the seventh in an 8 part series on “The Streetcar”.
The route of the streetcar will be substantially less than efficient for the purposes of transportation. If, as it’s proponents say, it will encourage development along it’s route, then to the extent that it does so, it will stimulate development in a form that is itself structurally difficult to serve efficiently with transit. Rather than helping shape future development into an ideal form, it will reinforce unplanned patterns from the past and be less efficient in the long term than it could be. Since many people have talked about the streetcar “shaping development” and even creating “transit oriented development”, it’s important to think deeply about what transit oriented development would look like and whether the streetcar would move us toward it.
I’ll make a clear example to illustrate my point before I apply the principle to a more subtle reality. Here we have a regular gridded street pattern and some regularly placed transit stops crossing it on the diagonal.
Let’s say that right now the whole grid is developed pretty evenly with two story buildings and that denser development grows around the transit stops over the next few years. Here are some contour lines so you can visualize it:
This doesn’t really look so far fetched as a development pattern for a city. Places like St. Louis have a long stretched out development pattern that seems similar at first glance.
But what would such a shape mean for transportation? The grid isn’t just decorative stripes crossing a flat surface. It’s a collection of rectangular barriers(buildings) lined up end to end with gaps(streets) in between them. Unless there’s a parking lot or a completely vacant parcel, you simply can’t cross a block diagonally. You have to follow the streets. If our transit line is underground, that isn’t a problem. Assuming there’s nothing else in the way, we could just take a straight line through each stop from end to end.
But let’s say that, like the streetcar would be, it isn’t underground and has to follow the streets. If we want to hit each stop, we’ll need to zig-zag.
Our little transit line here is starting to look a bit less reasonable. Pythagoras tells us this is actually a bit over 43% longer than the straight-line underground version. Further, there’s no way at all to make a shorter trip while we have to stick to the grid. Even if you were walking or riding a bike, there’s just no shorter trip to be made between any two stations. We can make a trip of the same distance that should be a bit faster, but it can’t be shorter. Both of the following possible routes are the exact same distance as our hypothetical transit line.
One thing classical geometry doesn’t account for is real-world intersections. Passing through an intersection can take a lot of time. Whether there are stop signs or traffic lights, you’re going to spend a significant amount of time not only waiting while stopped, but slowing down to stop and speeding back up again. Anyone who’s ridden a bicycle through Newport should be acutely aware of this. More important for our consideration though, turns can’t be taken at full speed even if you have a green light, so each turn adds time to the trip. Left turns particularly will slow us down. In fact, in an effort to save time and money, UPS apparently decided that their trucks would never turn left if they could avoid it.
So anyway, our transit line can be seen making a lot of left turns, right turns, and passing through a lot of intersections. It will also go 43% further than is strictly necessary. The alternative of course was for the transit line to run parallel to one of the streets for all or most of it’s length. A line that was fully parallel to a street would eliminate 11 turns, 5 intersections and 30% of the total length from the route while going the same effective distance. Recall that we’re assuming even density across the whole area, so a similar line simply angled in a different direction would serve just as many people and would do so with significantly less effort. Our example route is the least efficient possible choice for a gridded street pattern. A route that makes the line fully parallel to a street would be the most efficient possible.
This isn’t true just for transit, but for all transportation. The development that occurred around our line is diagonally crossing the grid. Since more trips will originate and end in the denser areas(there are more people and things there), more trips will be crossing the grid diagonally than would otherwise have done so. Bike travel, car travel, walking and transit would all be significantly less efficient in the long term because of the initial decision to build a stimulating line diagonally across the grid. On the other hand, there would be more reasonable paths to the average destination meaning that congestion could be better distributed if necessary.
Let’s express these ideas numerically so that we can compare reality more readily to our example. With the diagonal zig-zag, we go exactly as far in one direction of the grid as we do in the other. Let’s call this a ratio of 1/1. That’s the least efficient. If our line were to follow one street all the way, it would go the whole distance in one direction and none in the other. That would be 1/0, the most efficient. Where does the streetcar fall on that scale? It depends on whether you want to consider the extension to Vine street. Without it, the ratio is about 1/0.19:
With it, the ratio comes to about 1/0.28. Here’ I’m considering that the effective distance would be less(it doubles back) and that the route deviates back to the east again before leaving the grid.
That’s not awful. It’s not the worst possible route by this measure, but it’s 28% of the way to being the worst. If the streetcar simply went up and down Vine Street, as I’ve suggested it should for a number of other reasons, we’d see a ratio of 1/0, the most efficient configuration. Our measure of 1/0.28 can’t be written off as a case of reality being more messy than hypothesis. It’s a case of planners(or in this case, politicians) ignoring the euclidean realities of transportation in favour of sending some real-estate-speculation money more directly to established and popular constituents like Findlay Market.
The streetcar won’t be helping to shape the city into a form that’s easy to serve by transit. Transit and transportation generally is best able to serve people when they establish linear development patterns that follow reasonably good transportation corridors. The typical picture we see in the media of “transit oriented development” does little to consider this aspect of meta-orientation. It matters little if your cafe fronts the street if the street is out of the way of the transit line. Conversely of course, it matters little if the transit line goes right past you if you’ve got a fenced parking lot in front of your building. “Transit oriented development” needs to consider not only it’s human-scale orientation to the street, but it’s regional-scale orientation to major transportation corridors, including the orientation of gridded street patterns.
I don’t want to be misunderstood as implying that the streetcar is doing especially poorly here. There really aren’t any transit lines that take an ideal route through downtown at the moment, and they all certainly miss a lot of opportunities for redundancy and centrality that could by now have established a few major high density corridors branching off from Downtown if we’d let them. These opportunities were missed at some point and SORTA’s downtown/OTR routing is currently a giant mess.
No, I make these points not because I think the streetcar will actually make transportation substantially more difficult. I make them to point out internal consistencies in the arguments used to justify the streetcar. If as proponents said the streetcar would indeed encourage a lot of “transit oriented development”, it wouldn’t do so very well, and it wouldn’t do so in a way that’s in the best possible long-term interest of a city that wants to move toward increasing transit use. If we want that, we really need to develop linear corridors with redundant high-frequency transit lines that try not to cross grids on the diagonal.
I want to conclude by assuring you that I’m not just pulling this out of my ass. Linear developments that parallel street grids are absolutely everywhere that there are grids. If anyone can find me a truly non-parallel yet still linear business district or other denser development pattern occurring in a fully gridded context I’d like to see it. Here are some examples of my own, pulled pretty randomly from satellite photos:
Go do a little Google Earth exploring yourself and think about why Cincinnati wants to build a project, ostensibly to encourage development, that would violate this almost universal transportation oriented development pattern.