What a Traffic Engineer Thinks about Transportation

I ran across this video on a planning website I follow. It is originally from a traffic engineer, showing how "pedestrian friendly" the diverging diamond highway interchange is. I post it not for that per se, though it is funny to see their mindset on non-auto travel. I post it to show why our transportation system is so out of whack.

I think this echos a lot of what planners are fighting. If instead of traffic engineers, we had pedestrian engineers, things would look a lot different. Most planners tend to be for a balanced system, and when we compromise with the traffic engineer, it still sways towards the car.

My favorite line is near the end. "The design of this meets the standard engineer parameter of being able to move cars very quickly through here, and that being the first, second and third design criteria. And then in order to make it a complete street, in order to make it friendly to other modes of travel, we go down a checklist and see how we can accommodate all these other things."

Measures of Density

Those in the planning profession often come across different measuring units when it comes to various things like development projects or regions. Oftentimes, these get jumbled in the public forum and some folks cherry-pick numbers for their means. I'd like to discuss a few right now, and their implications towards planning vibrant urban areas.

Perhaps the most common to the public is people per square mile (ppsm) or kilometer. This is a great one for measuring a region or a certain area, especially for comparison purposes. New York, for example, has a population of 8,175,133 over 305 square miles (8,175,133 / 305 = 26,804 ppsm). Los Angeles population is 3,792,621 contained in 469 square miles for a ppsm of 8,087. Dallas' ppsm is 3,111 which is the population 1,197,816 divided by a land area of 385 square miles.

This works on a macro scale. Generally speaking, the higher the ppsm, the greater the urbanity. A look at the list of top five densest major cities reveals: 1) New York, 2) San Francisco, 3) Boston, 4) Chicago and 5) Philadelphia. If I were to make a list of most urban places, those five would certainly be in the upper tier.

The main caution in using this measurement is the boundary of the area in question. Some sprawl proponents will point out that L.A. is denser than New York. While that is true from a regional perspective (New York State has done a good job of preserving large portions of its countryside), the city is far more dense, and therefore far more urban than L.A. Transit use alone shows that to be the case (New York carries 12.8 million trips a day, L.A. has less than 1.5). As with any stat, a grain of salt and some perspective must be exercised.

A common measurement amongst developers and their development is the unit per acre. This is generally more suited for suburban, low density developments, like a single-family subdivision. Add the number of houses, divide by the number of acres and you get your number. A small development of ten acres with ten houses yields one. 40 quarter acre lots in the same development yields a four. It is also important to note, that unlike ppsm, units/acre does not consider infrastructure. That is a separate column for planners to deal with in their plans.

It can also work for urban developments, but often developers don't like those numbers to come out because NIMBY's will see it and automatically oppose it. Most downtown buildings would see that number well over the 100's.

This is also the most common measurement that NIMBY's use in opposing projects. They see the higher the number, the higher the externalities. In some instances that may be true. An apartment complex with a relatively high units/acre usually will generate a higher crime rate, traffic trips, pollution, but that is usually in the context of an auto-oriented area. Those cities in the top five densest generally have lower negative externality rates than their suburban designed counterparts per capita and in sime case straight up. Design and use can make a huge difference.

This measurement is in the middle on an area scale. It doesn't effectively apply to regions, but can and mostly is used above the individual property, like master-planned communities.

From an urban design standpoint, one of my favorite if the Floor-to-Area Ratio (FAR). It is also the most property specific. Reference the illustration as I explain this if you are unfamiliar.

From the property lines, if a developer builds a one-floor structure across the entire property, it's FAR would be 1.0, as the picture on the left shows. In the middle, the developer built the structure on only 50% on the property, but built two stories. This is also a FAR of 1.0. Now if the developer built three stories, it would be a FAR of 1.5 (.5 x 3 = 1.5).

For an urban area, it is optimal to have a FAR as close as equal to the number of floors as possible. This generally ensures better urban design and limits setbacks, which are a detriment to the street level and pedestrian experience.

Now there are several drawbacks to this measure, as with any other tool. It doesn't ensure that the streetscape will be pedestrian-friendly. It doesn't ensure it will have multiple uses. It doesn't ensure the users will engage in urban activity. The Empire State Building is a great urban building, but its FAR is far smaller than its floors because of the setbacks. Conversely, Harwood Center in Dallas has a near equal ration, yet is a sub-par urban structure.

When I look at downtown Dallas as a whole, I see a lot of buildings with a FAR that is half or less of the number of floors. Bank of America Plaza, Comerica Bank Tower, Chase Tower, Trammell Crow, Thanksgiving Tower and Energy Plaza are all in the top ten in height, but have drastically lower FAR's.

On the flip side, that isn't to say that a setback, and therefore lower FAR compared to floor height, are inherently negative. Lincoln Plaza has a pretty big setback, but at the street level, the space is used for greater sidewalks and pedestrian amenities. Conversely, they wouldn't need to do that if the sidewalks were wide enough and the city hadn't converted some of the space to give to cars for more traffic lanes.

Bottom line, Dallas has a downtown that looks dense from a distance, but when you get there, it seems empty. The big reason is the FAR is nowhere near as close at the heights appear. In essence, it is a false density. When critics say cities like Dallas can't support tall skyscrapers, this is what they mean. In an auto-based city, density doesn't work because cars need too much space for storage when you park. The more space in a building, the more parking you need. Many of those are surface parking lots, which have a FAR of zero, which is also their contribution to a vibrant street scene.

Update from the Bay

About ten months ago, I briefly chronicled the San Francisco area's strategies for battling congestion. Under the category of congestion pricing, tolls for area bridges and roadways went up when use went up. While many people look at roadway capacity as a supply-and-demand function, they don't like to think of those same economic forces are applied to roadways, if they actually have to pay for it. Which in that essence is why it actually relieves congestion.

The San Francisco Chronicle reported on a study that followed up on the strategy, and it appears to be working. While carpooling (a dubious attempt at congestion reduction) has decreased, so has main lane use. Transit ridership is up, vehicle miles traveled are down and travel time savings is up, tremendously in some cases. The extreme example is I-880, which saw its average travel times reduced by half!

The main problem with congestion pricing implementation on a wide scale is the lack of available case studies. However, of the ones that are out there, it appears that adding a market approach actually reduces congestion, more so than any other attempt that has been tried before.

More on San Antonio

While I took time in the last post to document the historical significance of San Antonio's downtown and then compare to Dallas, I want to take time to talk other things that SA did well in keeping their downtown active, and the opposite mistake that Dallas made.

Just a note though, everything likely could be traced back to historical significance in one way or the other. Downtown's were the beginning of every city. If there was no downtown, there was no city. The exceptions are suburbs and exurbs like The Colony, which are nothing more than auto-oriented suburban locales developed well after WWII. Some, like The Colony, are just developer driven places that incorporated sometime after development began or had finished. So when I talk about the street grid for example, know that is some form, it is San Antonio acknowledging its historical significance and building upon it, rather than Dallas, which was in a race to be the more modern city that could allow thousands of cars a minute through the area, at the expense of anything else.

Also, I don’t think, as someone implied to me after reading the previous post, that everything is perfect. One of the worst mistakes that Sun Belt cities did in the ‘50’s and ‘60’s was hem off the downtown area with freeways. San Antonio is no exception. The prevailing thought several decades ago was that the through traffic, the traffic that came from somewhere else and going somewhere else, was choking downtown streets and needed to be rerouted to ease congestion.

At this point in time, highways, like Rte. 66, went straight into the city core. So, prior to I-35, the highway was U.S. 77, which ran on streets like Lamar in Dallas. To ease this congestion, the prevailing thought was to build a freeway that would carry this through traffic around downtown, thereby freeing the locals from congestion and making getting to and from downtown easier.

Of course, now we know that there are unintended side effects. By making the auto more convenient to go around downtown rather than through, planners made downtown less convenient as a stopping point. So people who were passing through that would stop to eat at restaurant or shop at the stores now no longer did, since getting off the freeway was a pain. This had the effect of dispersing the urban area, simultaneously making downtown less attractive and encouraging suburban sprawl.

Paradoxically, it also didn’t relieve congestion downtown. The streets were just about as clogged as ever. My long promised post on the induced traffic principle will go into more details.

While the degradation of downtown's vitality was a slow process, the destruction of the urban fabric was imminent. Here's some pictures of our hotel.


I-37 in the background is the likely reason the prior buildings were demolished, allowing for the auto-oriented Day's Inn.



The parking lots in the foreground and the urban skyline in the background are the antithesis of each other.

 This hotel, a Day's Inn in downtown, is a typical freeway hotel, but inserted into the downtown urban area. Notice the expanse of surface parking and the proximity of the freeway. This may be San Antonio's biggest mistake downtown, but they are hardly alone.

However, I have to also give credit that some of the freeway loop is quite a ways away from the urban core, though that just pushes the negative effects further away. I-37 is 3 miles long on the loop. I-10's southern part is 2.5 miles, the western portion is over 2. Only the northern part of the ring road, I-35, is similar to Dallas' downtown freeway loop. This expanded geographic boundary is beneficial to downtown, though it still slices the urban fabric. It means there is a greater surface area within the freeway loop.

Another automobile-oriented mistake is the one-way streets. Luckily, this is in part negated by the fact that streets were not widened. Streets like Pearl or Young do not exist in San Antonio. They also didn't do things like create a Griffin Street within the existing urban area, which is in essence the same thing as adding a freeway, only a bit smaller in scale. Outside of the historical aspect of downtown SA, it's the lack of wide, pedestrian-adverse streets that create its vibrant setting.

And finally, for my WTF?!? moment, I give you this:

Why on earth can't Dallas, with its higher office and residential population not have a rent-a-bike. Surely visitor's who frequent SA aren't as likely to grab a bike in an unfamiliar setting? Just add to the list of the many things SA does right, that has usually been overlooked in other Sun Belt cities.
The good news is that a lot of this is able to be remedied. Elm and Commerce can be tamed by reverting back to two-way. The Deck Park over Woodall helps negate the negative effects, though the surrounding area is still freeway oriented and unlikely to change. A greater focus on urban form in new development to make sure that places like Dealey Plaza engage visitors would be welcomed. While I don't think downtown Dallas will ever score high vibrancy marks like SA does, but it isn't a lost cause. It just needs political will to get it done.

San Antonio, an urban oasis?

How timely that just a bit after my family and I visited San Antonio, Yahoo! Travel and Forbes but SA in their top 10 mid and small city downtown's, though how San Antonio with 1.3 million people, let alone Chicago, is considered mid-sized is beyond me.

Per the article:
For those who haven’t yet visited San Antonio, the city conjures up images of a tragic and bloody last stand at The Alamo. But for anyone who has visited, the city is more than just home to one of the most famous historical sites in the West. The San Antonio River Walk is perhaps the most beautiful part of the city, creating a verdant pathway lined with colorful café umbrellas that winds its way through downtown, offering up a bevy of shops, restaurants, and bars on the way. Tour downtown, follow the river by foot or tour it by boat, and save your visit to the Alamo for the late afternoon, when the sun is in retreat and you’ll have more to remember from your trip than just an historic and valiant defeat.

A bit brief, though what is there is accurate. San Antonio really has a lot of what folks like me, particularly in the Sunbelt cities, advocate.

We found it to be quite an active place, which begs the question of why. Though there is not one singular answer, and I will get into many shortly, the big answer is history. Obviously, the large scale historical framework is there with the Alamo and the Tower of the Americas. But there is also the smaller places that give it the historical feel. The difference between the Alamo and the other missionary sites is that the Texas soldiers choose that site as its fort. It isn't out of the question to think that the Alamo could be just another historical site in SA, but that a current missionary settlement building could have been where the battle was fought in 1836. These smaller missionary sites have been converted other uses, but their history remains. Often these uses are public, like a theater or performing arts venue.

But that isn't all the history. Six of the top 15 tallest buildings were completed before 1960. Five were built before WWII. To put it in perspective, Dallas has one before 1960 and none before WWII.

Aside from the parking garage on the left, this vibrant street scene is composed entirely of pre-WWII buildings. 

This is significant in two major ways. First, older buildings tend to be better urban buildings than those built between 1960 and 2000. There are ground floor retail locations and even those that aren't don't alienate those who are walking near the property. They are also better for the pedestrian scale. The materials are usually softer and the design is generally warmer to people up close. The second is that when a building built before WWII is demolished, the replacement is not of the same quality. More often than not, especially in the southern half of the U.S., that replacement is a parking lot, a known pedestrian adversary. By having large quantities of these buildings, San Antonio guarantees an active street scene.

Notice how this older building respects the street, and therefore enlivens it.

One of the most famous features of San Antonio is of course the River Walk. From a planning standpoint, this area fascinates me. Here was an area, several decades ago, that was a liability. When it flooded, there was damage and death. It was considered no more than a ditch at the turn of the century. The look and smell made the locals call it an eyesore. In the '20's, plans called for taming the river, including paving it, a la the Los Angeles River. The local Conservation Society took exception to the idea. They worked with the mayor and came up with a beautification project that would turn into the River Walk. The idea was very unpopular and it wasn't until the Works Progress Administration offered funds that the project got off the ground on a large scale.

Aside from paving and the actual completion, if I inserted the Trinity River here, would that sound familiar? What would SA look like today, had this area been paved over and become an open drainage ditch? This is a major tourist attraction because it is unique, beautiful and at the same time functional in flood control. SA took an asset, improved it and has been reaping the rewards since then.

Here's some pictures:

This is a great illustrator that the River Walk is both beautiful and functional. Instead of concrete tip to toe, stone work accents landscaping that fits the area, ie that is natural. If this were done today, one of two things would be the outcome. Either the area would be entirely concrete grey, to contain costs, or consist of imported granite and exotic vegetation that required extensive maintenance and died frequently.

I like this one as it illustrates the relationship between the street, the river and the built environment. I have heard that San Antonio is an example of how you can have a divided streetscape, basically debating that the tunnels can be successful within downtown Dallas. I feel differently. What you see above is the extension of the streetscape, not another entitly, like the tunnel system. On Friday night, we had dinner at Casa Rio, a restaurant with entrances at both the river and street level. While that can be achieved in the confines of a tunnel or skywalk, it is much harder, particularly when the buildings in question are post-modern office buildings.

This final shot also illustrates how well connected the two realms are.

It is hard NOT to find the street level in San Antonio. Stairs are plentiful and there are numerous times where it is easier to go to the other side of the river by going up the stairs, crossing the street and walking back down. While, as before, this may be possible in the tunnels, it is very hard to actually achieve.

The River Walk itself is wonderfully pedestrian-friendly. Yet, so were the streets above, which had just as much activity as below. It was easy to see how the design fed one to the other. Each would be less used were the other not there.

My main focus was what they did well in creating downtown SA. It is an area that is a bit odd compared to many cities. The tallest structure is the aforementioned Tower of the America's, it's tallest skyscraper is a hotel, the Marriott Rivercenter, and the tallest office, Weston Centre, is only the third tallest in the city. It is hard to find a city whose tallest structure is not an office tower. This represents downtown SA in a measurable way.

They don't focus on what other cities did or try to incorporate an off-the-shelf-planning idea. Instead, they took stock of what they had, and strengthened it. They didn't try to import a modern Times Square. They didn't try to build the tallest office building. They didn't call the latest and hottest architect to build a fancy civic building.

When compared to Dallas, they don't have a high downtown residential population. They don't have a huge amount of office space. They have more hotel rooms, but not that drastic a difference. Yet, despite that downtown Dallas should have a higher population within downtown at all times, but the streets don't reflect it. San Antonio has accomplished this by embracing what they are and what they were. Dallas has ran from it, trying hard to be more than it is.

Just to show this point, compare the two big historical sites, Dallas' Dealey Plaza to San Antonio's Alamo. Both were the location of a tragedy, though the Alamo was significant to Texas' independence, while JFK's assassination were black eyes to folks in Dallas. Both have museums dedicated to the event. After that, it is night and day.

There are lots of things to do around the Alamo after or before you go. The River Center Mall  and the River Walk allow for eating and shopping. As it stands now, all that is near Dealey Plaza in that regard is the Sixth Floor Museum's cafe (not open past 6pm and only on weekdays), a Subway and a western-themed gift shop. Not that far, but out of eyesight of the Plaza are a few more restaurants. If you want to visit and pay your county tax bill, that can be done at the Records Building. If you want to visit then join the army, you can accomplish that at 207 South Houston. If you want to visit Dealey Plaza before your county court date, the fortress-like George Allen Courts building is adjacent. Aside from the museum and and its cafe, the only directly adjacent building that caters to visitors would be Old Red Courthouse, though if you are at Dealey Plaza, it is only a building that looks neat. Otherwise, visitors have no idea what it is. If visitors know that the JFK Memorial is only a block away (some don't) it is highly underwhelming and only makes sense when you realize it is nothing more than a garage topper.

It is this scattering of parts that make downtown Dallas so lackadaisical in activity, particularly when compared with SA. Compactness plays a huge factor in urban street vibrancy. Dallas doesn't have it, San Antonio does.