All posts by Adam Bejan Parast

This post originally appeared on Orphan Road.

Ever wonder how mode choice is modeled? If yes read on…

Mode choices models came to the transportation field via psychology. These models were created to account for the competing forces populations take into account when deciding between a set of options. The model essentially attempt to re-create how people weight the costs and benefits of each mode.

I would first like to walk you through utility equations for each of the modes. When mode choice models are trying to determine how a population will travel it computes the possible utility values for each mode and then compares them to each other. The larger the number (i.e. less negative) the higher the utility and the more desirable it is.

U = utility
TT = travel time

U(sov) = -0.189*TT – 0.0151*cost

The SOV is used as the baseline against which everything else is measured to. From the SOV utility equation you can determine the inferred cost of time. It is very simple and essentially takes into account how long it takes and how much it cost. The travel time includes “terminal time” i.e. getting to your car and then parking and walking to your destination. Cost includes operational cost as well as parking.

U(hov) = -4 -0.189*TT -0.0151*(cost/occupant)

The constant at the beginning of the equation shows that this mode is inherently less desirable than driving alone. The utility of time has not changed and the cost are split between the occupants of the vehicle.

U(bus) = -8 -0.189*TT -0.0151*cost – 0.291*wait -1.427*#transfers

As you can see determining transit utility is much more complicated. The inherent utility of transit is much lower. The utility of time has not changed but the value of waiting is much higher. This essentially says that waiting for the bus for 5 minutes feels like riding the bus for over 7.5 minutes. The last value is the “transfer penalty” which accounts for lower desirability of transferring even if it will be faster. In this circumstance one transfer is equal to about 7.5 minutes.

Next the utility for each mode is raised to the natural log (e^U). These values are summed and then each mode’s utility raised to the natural log is divided by the previous sum. This will give you the mode split probability. The number of trips from one place to another is multiplied by these probability and you’re done!

Below are a few graphs that I made to show what the model predicts will happen with certain changes. I purposefully did not show numbers because they are not calibrated and I only wanted to show the trends. Scenario 1 has the lowest auto cost and time while Scenario 8 has the highest auto cost and time.

You can see that this models shows that SOV’s are much more sensitive to increases in prices than HOV’s. This makes sense because the utility equation divides the cost of the trip between the number of occupants. You will also notice how it takes a while to before the bus starts increasing. This is because it has such a low inherent utility.

In this graph you can see how increasing travel time for SOV/HOV while keeping transit travel times constant can change mode split. You can see how both SOV and HOV shrink at the same rate because they use the same utility constant for travel time. You can also see how the change is not linear. This is a result of setting a negative number to the natural log.

The last graph is a combination of the first and second graphs.

Coming Next: Delay Calculations

This post originally appeared on Orphan Road.

I almost want to say Boo Ya but I won’t because there is one last alternative to the surface transit alternative. I really commend the state for throwing out all of the alternatives that should obviously not be advanced. Chopp’s alternative didn’t solve any problems (and just created more), and no matter how nice the tunnel sounds there simply is no money for it and if there is no money it will not happen. So the state made the hard choices and threw them out as it should have.

I would like to point out how the so called “grand compromise” was simply a political stunt by those that don’t want a surface alternative. They knew they had lost so they tried to circumvent the process at the last minute. The state rightly shut them down before they could even get momentum.

We should know what the governors choice is by the end of the year. I would be shocked if it isn’t the surface alternative. Now the major choices will be where transit money is spent and where is comes from.

This post originally appeared on Orphan Road.

Any regular rider of Metro will be familiar with scenes like this, this and this. We are all use to it and I’m actually pretty suspired how well everyone deals with it. It is especially useful when the bus driver lets people off the back instead of making them squeeze down the aisle.

This problem is especially bad on the latest new flyer 60 foot articulated buses. The aisle in the front of the bus is very narrow. It is very hard and involves a good amount of maneuvering to get past someone in the aisle. Not only that but the articulated section no longer has anywhere to hold on to. You basically have to make a mad dash from the front to the back sections and hope the bus doesn’t turn.

Regardless of which type of Metro bus you are on this is almost always a problem. So why not take out seats? I’m guessing the major reason is that metro and transit agencies in general assume that people want to sit. I know I do but what about all of those people that are standing in the picture above. I’m sure they have come to expect it. I know I do if I’m getting onto a 7X.

Metro should take a proactive role in improving the capacity and ridership experience by better accommodating these riders. In this case making it more comfortable for riders to stand, i.e. making more room for them and giving them more places to hold on to.

Take a look at the pictures below that I took on my trip over the summer. This is what all of the buses in Spain look like. Notice all of the seating in the back? Parents with strollers board in the middle door and have plenty of room to maneuver. See the lean too seats on the left? They are very helpful as well. Circulation and standing room is prioritized in the front while seating capacity is prioritized in the back.

The next two pictures are from Venice. The buses still fill up but people standing are so much more comfortable. As you can see people are three wide and if someone needs to get off it isn’t hard for them to get to the door. All of the seats in the front are one wide and either face forward or backwards. Sideways seats like Metro’s aren’t better because you still only have room to stand one wide, and if you’re sitting down someone’s bag is usually right in your face. Not fun.

The next two are in a suburb of Munich. This was on the way back from a concentration camp and most of the people on the bus were American. See all the hand rails, especially in the articulated portion. Near all of the doors there is no seats which allows a huge number of people to stand there. The articulated portion of the bus also has lean too seats which I personally think are a much better use of that space than the mickey mouse seats that metro uses (if four people are sitting down good luck getting past them without tripping).

The last two are from the Paris Metro system, but I think it shows just how flexible you can get if you want to improve crush capacity while still providing more seating. These seats are located next to every door on the 8 line. When the train starts to get really crowded people sitting down stand up, freeing up a good amount of space as well as improving their comfort. They have something to lean against as well as not having bags in their face.

I’m essentially saying Metro should try out some of these ideas. They work in the rest of the world so there is no reason it can’t work here. How about removing some seats from of 7X buses or chronically overloaded buses. Another big concern of my is the RapidRide buses. If Metro wants these buses to be attractive and “rail like” it seriously needs to consider strategically removing seats so that riders can quickly get in and out. It will not be a good solution for all routes but it is just one thing that Metro can do to improve the rider experience on the cheap.

This post originally appeared on Orphan Road.

Well it has been a week since I posted this. I know that over 50 people downloaded the file so fill them out and get them back to me. I promise you I’ll create some cool graphs. I hope it helped people be more contentious about what decisions they make when choosing modes.

Here is mine. I usually drive more on the weekend (to see my dad in Kirkland) but I have been a homebody because of finals. As you can see I have great transit accessibility in addition to living close enough to everything to making biking and walking a daily part of my life. I own a car but most of the time it is easier, cheaper, faster or more enjoyable for me to walk, bike or take the bus. I usually bike to school (unless it is raining) and take the bus to work downtown. It is actually kind of ironic that I own a car because I only have it for my last job which was up in shoreline where I worked for WSDOT. Go figure.

This post originally appeared on Orphan Road.

Via with a few changes.

“Local government finances are so dire, it is time to consider — and enact — an annual fee on pedestrians.

A $25 annual fee for walking is a natural outgrowth of the enormous amounts of trails, sidewalks and accommodations the region has made for pedestrians. Those funds would be useful for local cities and King County. It would also make pedestrians true members of the world of transportation, rather than free riders on the tax rolls.”

Sound ridiculous doesn’t it.

This post originally appeared on Orphan Road.

To start does anyone know where I can get a copy of Jan Gehl’s report on the viaduct? Here is a quote of his from an interview that I just watched.

“The amount of traffic in any city in the world is arbitrary, it is a matter of how much asphalt you gave them in the first place.” Jan Gehl, (via streetsfilms)

Yeah he is good. They had lots of his work at the architecture center in copenhagen when I visited this summer.

On a similar but unrelated note take a look at this bike lane on the upper west side! Have they gone mad?!? We don’t build bike lanes that that is the US. It makes our bicycle master plan and sharrows look a bit mickey mouse doesn’t it.
(via streetsblogs)

If you haven’t started reading streetsblog get with it. It is tad NYC centric but there is lots of great information, especially bike related.

This post originally appeared on Orphan Road.

Per my travel demand forecasting post a week or two back (which I will be blogging about in the next few days) I decided to start tracking my mode split. In the process I ended up creating a nice little excel spread sheet to track myself, and I thought that it would be awesome to see what orphanroad’s readership’s mode split is. After all the more information we have the better choices we can make.

So if you want to track your mode split download this excel file. After you’re done e-mail it to me at adambp@u.washington.edu . I want to do a little data manipulation and see if I can draw any conclusions.

This post originally appeared on Orphan Road.

Why doesn’t seattle have an agency like the Portland Development Commission?

This post originally appeared on Orphan Road.

So what do you think? Can I get it’s about time in the house!

One Bus Away is starting to get attention. Seattle Magazine gave it a great review. Hopefully Metro is taking notice.

ps sorry for the horrible picture. I’ll get a better one soon.

This post originally appeared on Orphan Road.

This is an intersting article about NIMBYism in SE Seattle