Thursday, August 10, 2017

SLC Central Station

UTA's free fare zone map leaves something to be desired.Free Fare Zone Map
 It shows the TRAX, but not the bus. When I look at the bus map for downtown SLC, there is a lot of service there! UTA might do better just combining the two maps, given their near-identical extents. Here is my MS-PAINT take on such a map: (Gray line with FFZ acronym)


 On a proper mapping program, I'd use a specially dashed line, perhaps using arrow symbols. Using a shader or a hash would obscure the information inside the box.

If UTA wanted to move away from a free fare zone, they could designate certain stops or stations, rather than an area.

So... looks like either 200 south or North temple is a really nice place to put a central station. State Street and 200 South, specifically...

Jane Jacob's Density

Great  blog post here: "Squeezing Jane Jacobs Density". The comments are also worth a read. 

I'd like to do a bit of expository thinking on this bit of text:

....your lower units start losing access to sunlight at 4+ story heights. Even Jacobs notes the disadvantage of coverage that is too high in Chapter 11, discussing the North End in particular. The block on the left side of the North End photo at the top, for example, had 72% building coverage in 1960 - way too high for comfort for her (actually, she called it "intolerable"). That is why it was 123 DUA in that 4-7 story height range. 
For most 1-5 acre lots, 60% lot coverage for 6+ story multifamily development is a sober number not to surpass for your development. If you want to hit 150 DUA with this, you will need to go to at least 8 stories to secure adequately sized multi-bedroom units.  That's what 150 DUA looks like at a bare minimum with underground parking.  If we elect to squeeze 150 DUA into 6 stories instead, we are going to be building too many one bedroom units - exactly what we shouldn't be building, according to Jacobs, if we want to promote diversity! To use her terms, that would "standardize" your development to stamp out diversity.
Two topics it brings to my attention: First is the matter of density, building height, and lot coverage. The second is the difference between lot coverage and block coverage.

Density is a bit 'squishy'; it's a zonal measure of intensity, or the number of of things per areal unit. But what thing is used as the metric generates very different results. Population, employment, dwelling units, and square feet/square meters are all used, and the ratio between them is rarely constant. Which is troublesome, as zoning regulates the built environment using all of the above.

I live in a 1.5-story four-plex, which has four units, and 2-3 people per (2 bedroom) unit. So about 10 people. Total square footage (including the shed) is about 3000 SF. My mom's single family suburban houses is a 2.5 story single family detached, with one person in it, and is about 3000 SF. Very different styles of housing. I'd hazard her lot coverage is lower than mine, something like 50% vs. 70%.

My mom could probably triple the number of dwelling units on the lot by refinishing the basement, and add another unit by retrofitting the top floor. (I lived in a large old house that bad been so converted). Parking would be a non-issue, with the garage, RV-pad, driveway, and on-street parking.

Thursday, July 6, 2017

SLC Free Fare Zone

UTA's free fare zone map leaves something to be desired.Free Fare Zone Map
 It shows the TRAX, but not the bus. When I look at the bus map for downtown SLC, there is a lot of service there! UTA might do better just combining the two maps, given their near-identical extents. Here is my MS-PAINT take on such a map: (Gray line with FFZ acronym)


 On a proper mapping program, I'd use a specially dashed line, perhaps using arrow symbols. Using a shader or a hash would obscure the information inside the box.

If UTA wanted to move away from a free fare zone, they could designate certain stops or stations, rather than an area.


Friday, June 30, 2017

Streetcar vs. Automobile in 1917

Free roads and free parking subsidize the automobile. Why not transit?

"Because it benefits so few people--only 3% of people take transit to work".

And how many people took automobiles to work in 1917*?

"..."
That's right. Because we have no idea.

MODE ACCESS

 We know that about 30% owned cars. (No idea how many had access to transit--have to find that out someday)




Compare that to the number of people who were riding transit at that time:

TRIPS MADE

In 1917, there were 14 Billion transit riders, so about 131 transit trips for every person in the United States. Sadly, no data for auto users, so we still can't make an apples-to-apples comparison.

MILEAGE DRIVEN

We have some estimate of how many automobile miles were driven: About 30 billion. Or, for a U.S. population of 106.5 million, about 289 miles a year. With 260 working days in a year, that is about a mile a day.


Data for transit is proving difficult to find, and even APTA doesn't have it for before the 1970's. The best they've got is vehicle miles**:  In 1920, there were 1,922 million vehicle miles (1,922,000,000)..but that's just how far the trolleys traveled, not how far the people on board them traveled. Without knowing how many people were on board, we can't compare person-mileage.


*Streetcars reached their apex in 1917, the same year Federal funding of roads started. Whether the Feds just switched to what would have been the winning horse anyway is difficult to know.

** I'm leaving out subways and commuter railways so there can be no "that's just New York" whining.

Urban Phase Shift?

One of the comments on this article was so great I had to repost it:

When I took my Urban Economics course from Barton Smith, one of the observations Smith told us in class was that whenever prices for major goods and services in an urbanized area keep going up (and housing is certainly a big part of most people's budgets), eventually prices will reach a point where they will become a market signal to everyone that the urbanized area needs to stop growing. Population growth will either come to a halt, or people will start leaving until prices fall to an equilibrium where people can afford to live there again. - Neil Meyer 
I think it gets to the core of why city promoters like transportation improvements--without affordable housing, cities can't grow. Affordable housing includes both rents and access costs. As rents in one area rise, people can offset that by moving to nearby areas with lower rents (and higher access costs).
In pre-industrial (and third world slums) the only access available is by walking, and so some truly hideous densities result.

It's theoretically feasible that a city might stop growing***. But most cities don't--instead, they invest in transportation improvements. NYC built it's first subways in the name of "De-Congestion".

One of the ideas I'm kicking round is an urban scaling induced 'phase shift' in the effectiveness of transportation improvements. Namely, total metro population drives average metropolitan density. (As you get bigger, you naturally get denser). At small sizes and low densities, auto-mobility works: Land is cheap, parking is available, walking anywhere is madness. And it keeps working, as long as your addition of automobile capacity keeps up with congestion.

However, while travel is an 'derived demand' in terms of the number of trips made, it's a 'induced demand' in terms of the length of trips made. If you make traveling cheap and easy, people go further.* Urban form is 'set' by the dominant transportation mode at the time of construction**. So places developed under conditions of auto-mobility tend to be low-density with segregated land-uses. The large amount of travel required to get around for basic needs is 'baked-in' at that point.

This is problematic, if the metropolitan area keeps expanding.

from: https://people.hofstra.edu/geotrans/eng/ch6en/conc6en/cellular_automata.html

As the number of zones increases, the average distance from one zone to another also increases. Which means, all else equal, the amount of travel required to get to all the places you want to go also rises. Simply because things are scattered about: home in one place, work in another, groceries in a third, kids-school in a fourth, soccer in another, ballet-practice in another, dentist in yet another.

The big problem is that the increase in average distance between all of these things is non-linear. Every additional 'zone' you add to a city, the average distance rises more than it did for the last zone.
Even if the road lane miles per capita (and associated costs) remain constant, the amount of travel doesn't. As travel demand outstrips supply, congestion results.

Some cities try to fix this increasing congestion with massive increases in road-building. Failure is inevitable. Exponential increases in travel require exponential increases in road capacity, imposing exponential costs on a linearly growing population.

And so at some point, every city gets the 'rapid transit bug'. And it has to be rapid transit, because only rapid transit makes it possible to avoid congestion. Non-rapid transit, such as regular buses and streetcars, are undeniably cheaper to build than rapid transit (sometimes by an order of magnitude).

But that doesn't matter. Rapid transit is premium transit*****. It's transit for choice riders (people who could drive, but choose not to). And to get people to make that choice, it has to be better (in some way) that the driving alternative.

Non-rapid transit suffers from congestion. It's less convenient, less reliable, and less comfortable than  your personal automobile. You don't have a 'locker' to store things in, and hauling groceries is difficult. Thus, it can almost never compete with a private automobile (excepting when parking costs/hassles are enormous).****

Rapid transit is better than the personal automobile when it is a) faster, b) cheaper, and c) more reliable. 'a' only happens when congestion is fierce; transit vehicles make repeated stops. 'b' seems simple, but for most people a car is a 'stock' of mobility they can draw upon even with no money, while transit is a 'pay-per-use' thing, so it seems expensive, even if it is less expensive in aggregate. Again, 'c' is reliant on congestion to work.

In summary: Auto-mobility works until it doesn't. It stops working because average travel distances increase exponentially as the metro area expands, while population increases linearly. This makes it impossible to keep expanding roadway capacity to match demand. (Some try; all fail). As travel demand outstrips supply, congestion results.

The total amount of delay drivers experience is exponentially proportional to the amount of congestion (from: https://ops.fhwa.dot.gov/congestion_report/chapter2.htm) The AADT/C ratio is the ratio of traffic to capacity.



-----------------------------------------------------------------------------------------------------------------------

***This may be one of the reasons for competing cities, closer together. When a city reaches maximum walkable density, it makes a great deal of sense to go elsewhere. Of course, large cities have huge advantages in terms of access to resources and agglomeration economies, which (typically) more than offset the cost of congestion. I expect the only time you'd really see such a switch is for 'Twin cities' like Minneapolis-St. Paul, or the Texas MetroPlex.

*The reverse is also true. As congestion increases, trip length should start falling.

**The trouble being that urban form is fixed at date of construction, and is very difficult to retrofit for alternative transportation modes. Adding highways to NYC came at enormous financial and social cots. Retrofitting auto-dependent cities will likely be painful/costly as well.

****Which is why buses to downtowns, Universities and hospitals work--they are all places with terrible parking.

*****The political quid-pro-quo of rapid transit for dependent riders is that "Hey, you too can ride the premium transit!". The flip side to that is that the high cost of rapid transit means less of it is provided--its goes fewer places. Typically, bus operations get cut to pay for capital improvements, which leaves the transit-dependent population worse off.

Thursday, June 29, 2017

How does the WFRC model deal with trip chaining?

Was drafting a blog post on trip lengths vs. trip frequency, and the though struck me:

We know that the evening peak is longer and 'lower' than the morning peak. I think that's because people run errands after work (rather than before work). 

Economically speaking, as congestion worsens, the average amount of distance per unit of time falls. As the cost of that time rises, people travel less. I'm thinking that the way people travel less is by chaining trips together. 

The home to work journey is typically the longest people make. Assuming that journey is the hypotenuse of a triangle, the maximum journey  of chained trips is an equilateral triangle. Given the triangle inequality (the sum of two sides is always greater than the third), the minimum diversion is tiny. Looking at the maximum diversion, the greatest distance from the hypotenuse is radical(3)* the hypotenuse, or about 87% of it. So for any trip up to 87% of the distance of your work trip, it makes sense to chain that trip with the work trip. 

I know the WFRC model has HBW, HBO...but is there a WBO (Work-based other)? Or does that just get rolled into the HBW?

BRT vs. Traffic Lane, Part 3

Continuing our series on BRT vs. Traffic Lane (Part 1, Part 2), another exploration how how the two compare. Mike Brown observed that:

  1. A 5-minute, fully loaded BRT would carry about as many people as a standard Arterial lane
  2. Unless you can trust that you can fully load each bus for an hour, then a 5-minute BRT will not move as many people as standard cars would.
  3. That's not necessarily a reason to go with cars.  Cars create car dependency, and they max out in what they can carry, but BRT can be increased to more than 5-minutes.
  4. "BRT" need not be a single route. In many downtowns, some block segments have a bus each minute, and sometimes more often.  
  5. Dedicating a lane exclusively to buses in these cases will result in more people per lane, assuming most buses are quite full.
  6. If automated vehicles and vehicle sharing begin to overtake private ownership, it is possible to imagine lanes where auto occupancy might reach 4 or more passengers carried in "minivan"-type vehicles.  In this "jitney-like" transit scenario, lanes even outside downtowns can start to carry far higher numbers than 5-minute suburban BRT," which is very aggressive service for suburbs.

Mike came up with the following numbers:


I'll add a few comments to what Mike has said.

1) I don't think it's physically possible to run 60 buses an hour, even dedicated bus pullouts. That would require a bus to decelerate, board, rejoin traffic, and accelerate. Even with elevated platforms, off-board fare collection and multi-door boarding, I think that would be a hard standard to achieve. And even one late bus would make all the buses in the queue later, and congestion would ripple down the line.

 The really serious BRT routes (Gold Standard) have four lanes: A curbside lane (to reduce time spent re-entering the travel lane) used for boarding, and a bypass lane. This seems to permit operations at headways as low as a minute and a half. But that would be four lanes, and outside our scope of analysis. Hit with capacity constraints, the current solution is to make a bus more train-like, but adding another unit, using double-articulated buses rather than just articulated buses. Double-articulated buses with capacities up to 180 are currently in use in Utrecht. Volvo has a 300 person capacity bus that is being tested on the TransMilenio.

2) Rare is a system that could load such a bus so heavily. But it might be possible. Daily ridership on route 830 (the route that the Provo-Orem BRT is to replace) reached 3,000 per day. The BRT was projected (in 2011) to have 12,900 daily riders. Assuming 10% of ridership takes place in the hour of the morning peak., that's 1,290 riders. Assuming the planned five minute headway is used, that's about 107 riders per bus. Or course, they won't all be on the bus at the same time. But it does suggest that the Provo-Orem BRT will be pretty heavily used. In 2030, the BRT is projected to have 16,100 daily riders, or about 137 riders per bus. Again, they won't all be on the bus at the same time.

3) BRT does scale better. Moving to a double-articulated bus would boost capacity to 120. At five minute headway, such a bus could carry 1400 persons per direction per hour , greater than a major arterial at 5pm. Alternately, just adding 3 more buses (to boost headway to once every 4 minutes an hour) increases it to 1400 persons per direction per hour. A bus every four minutes seems like something a single lane could manage. TRAX puts a train through an intersection every 5 minutes regularly (400 S. and Main). On 'crush load' (game) days, it might be as high as double that.

4) Branded Bus Corridors are a great idea. But they are only as long as the 'rainbow' portion of the corridor, where multiple lines overlap. Beyond that, you have to transfer. TRAX is a 'rainbow' corridor from 2100 South to Courthouse station. For trains with limited amounts of guideway, service laps are almost inevitable. But for buses, I'm not sure about inter-lining services: Does it just add more confusion? I think it only really works when buses are converging on a termini. I don't see it on the Salt Lake County or Utah County map, but you can see where one should be branded on the downtown Salt Lake Map: State Street from 5th South to North Temple, and thence west along North Temple to 300 West. All of North Temple could be branded, and both 200 South and 400 South might also be candidates.

5) The key question is not "Will the buses be full?" but "When will the pavement carry more people as a bus lane than as an automobile lane, during the peak hour." Not at five minute headway and 90 person loads, but at 100 persons/bus (at 5 minute headway) or 80 persons per bus (4 minute headway), a bus edges ahead. Based on the 2030 numbers, it seems likely that a BRT is a better long-term investment than a traffic lane.

6) A full discussion on automated vehicles is going to require a full blog post.