Food Truck Report Madewell AND
PRARIE HOME COMPANION
THE FUTURE OF McLEAN
The Hydraulics of Traffic ISSUE #5 MAY28, 2012
COVER PHOTO BY TYSONS ENGINEER FIAT FLOW ALL PHOTOGRAPHY AND GRAPHICS WITHIN THIS PUBLICATION RIGHTS RESERVED TO THE ARTIST
The Hydraulics of Tr a f f i c
We Are Looking For Writers MADEWELL Event Tysons Corner
FOOD TRUCK WATCH ATIP and The Bratwurst King
Tolls and Their Finite Funding THE OUTER BELTWAY
Art Scene in Northern Virginia
McLean Stuck in the Middle With You
THE HYDRAULICS OF
Imagine you could float over a transportation network and view it at the network scale where cars would begin to appear as a single moving mass. Individual blips of the road would be ironed out and intersections/ramps would appear like nodes. What you would see would be familiar to anyone who has ever seen water running through a
channel or pipe, but how far do the similarities run? The mechanisms that control the movement of water through a channel or pipe are not independent of other elements in physics. Friction governs where water runs, how fast in flows, and how much energy the flow maintains. This friction is dependent on two elements, the velocity of the flow and the characteristic of that flow (turbulence
and fluid composition). The faster and more non-uniform the flow becomes the more friction occurs at the walls of the pipe, thereby removing energy from the system and eventually being able to stop all flow all together.
Interestingly though the same high velocity and turbulent flows also provides the highest flow capacity within the pipe. The faster water moves through the system, the more of it you can move.
Vehicle traffic is very much dependent on the same characteristics as water flows. Velocity provides the capability to move a lot of traffic through a system, like a highway, but higher velocity roads are also more vulnerable to curves in roads, sudden reductions in speed due to lane reductions, and overall traffic incidents. The characteristic of a traffic flow also is important, and this is the element which most traffic analyses do not consider. Turbulence in traffic flow would be characterized by several differing vehicle types (large trucks, small trucks, SUVs, sedans, and motorcycles) which all have independent movement patterns (braking and accelerating). Turbulence would also be indicated in large movements from one side to the other of a road which would exist in locations where many different traffic movements are happening (imagine the mixing bowl with many people changing lanes). Overall energy loss in fluid and transportation congestion increase, ie the loss of energy in the traffic flow, are correlative.
So the flow is similar, but velocity and flow type canâ€™t define everything can it, what about pipe size, pipe material, and other non-flow characteristics? Absolutely, the system itself has as much if not more implication on how
the flow operates, in fact it is iterative. Modifications to the pipe system will make impacts to the flow characteristics by modifying turbulence and velocity, and much like in traffic, the difference between optimal flow characteristics and failed flow characteristics occur quickly due to the exponential nature of the dynamic. The different pipe size and material could be directly analogous to the number of lanes and the lane width/presence of shoulders of that road. Finally, one might wonder what intersections, ramps, lane reductions, and other system modifications could be modeled as in hydraulics. All of these are individual nodes where a spot occurrence exists. In hydraulics objects in a water network like crosses, tees, bends, valves, and reducers all have equivalent friction impacts on a networkâ€™s energy. In other words when water flows through one of these objects, energy is lost on the other side of the object. In fact these objects, compared to the amount of space they use, are the most impactful elements in a network in energy loss. In traffic patterns this can also be seen at major onramp systems (crosses) which congestion flow back upstream the system, traffic lights (valves) which might not operate appropriately, and reducers (lane reductions) which bottle neck flow into a sudden smaller flow area.
The Tysons Corner is a website in its infancy, started in 2011, created BY to discuss the local issues DESCRIBING THE specific to eastern Fairfax COMPLEXITY OF including the regions of Tysons Corner, Falls OWN BACKYARDS Church, McLean, Vienna, and Merrifield. Our goal is to provide a deeper analysis of progressive topics centered around the new urbanism concepts of a 21st century E N T E R TA I N M E N T Northern Virginia. We have seen the region grow W R I T E R S from a quiet suburban community to a cultural U R B A N I S T S and economic contributor of the east coast rivaling other more established T H I N K E R S A N D cities. The area for many grew without I N N O VAT O R S years direction leaving a disconnected community A R T S C E N E of micro-developments R E P O R T E R S without any coordinated design concept. Our goal is to create a unified, or cacophonous, voice of residents and interested parties to discuss what the future vision for the
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region could or should be. We look to fill the questions that many have and provide the depth of coverage that is difficult for overall news publications to provide.
We are currently looking for interested bloggers who are looking for a forum to discuss their ideas as a writer for TTC. This could be done as an exclusive TTC format or as a cross post with other independent blogs. If you are interested in reaching a large base of readers specific to this region think about joining. Please feel free to contact us; firstname.lastname@example.org
had a great little styling event this week at Tysons Corner and the lovely DC blogger Sydney from The Daybook was there to hang out. Her blog is on my daily must-read list, so it was really nice to see her super sweet and stylish self! There were macarons, cupcakes, Jones sodas (with polka dot straws), a hair braiding bar, a great DJ, and some Madewell sales! I happily had a Jones while I shopped around for a few pocket tees (not black or grey, per my â€œwear more colorâ€? resolution) and white shorts. I wish shopping was always like this!
Like The Constant Shopper and want more? Follow @diaryofd on Twitter or at her personal blog
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FOOD TRUCK WATCH The world of Food Trucks is a competitive battle of positioning and word of mouth. Often times that means that a person has to pick one truck specifically over another. I try to spread the love around as much as possible but until this past week I had not had the chance to show some love to a
Follow us on twitter for daily food truck alerts forwarded from the trucks.
new truck in Tysons, ATIP.
You may have seen ATIP around recently and one thing that intrigued me was that they had both breakfast and lunch time stops in Tysons Corner. On a particularly crowded day last week I chose to try something new. Having never seen their menu before I was shocked when I found out there was a Gyro/Falafel truck just begging for my patronage. Gyroâ€™s, for those of you who have never tried one, is a delicious slow cooked meat with a subtle tahini sauce or yogurt, served on a soft and seasoned flat bread. ATIP fits this description to a tee, and on top of the delicious seasoning and flavors their gyro is a traditional slow roast lamb that melts with each bite. Their falafel is good too, for you vegetarians who might be feeling neglected by most food trucks. I rounded out the lunch with some samosas, which unlike the Indian version, was formed a thin filo pastry. It was one part samosa filling and one part spanakopita. It was crispy and delicious. All of the selections are provided at 5 bucks which I thought was a great price option for those who like a light, healthy, and affordable lunch. I didnâ€™t have a chance to talk to the food truck owner but from what I could tell this was a family run operation, mom, pop, and son. Either way it tasted authentic and made me take notice. From now on ATIP will definitely be on my Food Truck watch.
The Bratwurst King Hit the spot last week. Who knew German food could be paired so well with Indian food? Curry Brats are just what I wanted. The schnitzel was freaking amazing also, and when I ordered it I had no idea that it was going to be that huge. That of course was only exaggerated by the comically small pretzel roll that it came tucked between.
The sauerkraut was really great and went very well with the brats and pretzel rolls. The food did as it was promised, it brought a bit of old world europe into my afternoon. If you are looking for a quick bite or something light then look elsewhere. If you have a man sized hunger that needs spicy mustard and fried meats then welcome to the old world. Danke Schoen PAGE 9
For two years urbanists, traditionalists, conservatives, liberals, planners, and residents have all argued about the ghost project that never disappears, the outer beltway. Many of the outer beltway supporters have noted several studies that do show that a second bridge could help relieve traffic on 495 caused by BRAC, unfortunately the outer beltway only addresses a small portion of the true cause to this traffic and does not achieve any real results in the urban and commercially viable regions of northern Virginia. While a bridge crossing at Ashburn might help a lot of residents who work in Maryland, there would be almost no private funding assistance with this pathway as the region in question is substantially residential in nature. In the absence of commercial business leader funding, who overwhelmingly are in favor of mass transit in place of road improvements instead, the bridge crossing would need to be a tolled system. Based on the speculated 3.5 to 5.0 billion dollar cost of this crossing project and ICC-like roadway project, the tolls would need to be quite significant. Imagine trying to build the entirety of the Silver Line project on ONLY tolls. As much as people have complained about the funding via tolls for the Silver Line, which is anticipated to total about $2.5 billion, imagine how hefty of a fee would be required for a fiscally solvent project which costs double that amount.
This was the best salad I have ever eaten.
Donâ€™t expect the State to help out too much, considering how hard it was to get $150 million in funding of the Silver Line. Then again, the state has been willing to help with highway projects thoughâ€Ś double standard perhaps? Either way, the toll revenue would need to be significant to pay back this project even if Virginia helped with $500 million (only 10% of the cost).
So how much would the toll have to be? Well the Dulles Toll Road has about 160,000 commuters per day (80,000 each way) of which approximately 90,000 (45,000 each way) come from Loudoun County based on VDOT’s “Annual Average Daily Traffic Volume Estimates By Section of Route”. Of the 45,000 residents in Loudoun County that use the Dulles Toll Road, only 15% are anticipated (pending the current resident/destination analysis being performed) to work in Maryland and would be users of the outer beltway. If this same percentage were applied to the 15,000 users in Fairfax County that are adjacent to Loudoun County the total number of prospective outer bridge users would be 9,000 total residents (or 18,000 total crossings). First, one can see that this really won’t solve any traffic problems that occur the closer we get to the city, but it might be a political sale to Loudoun county residents so let’s continue. With most capital projects that attain private backing, such as the silver line bonds, a payback period could be anywhere from 10 years to 50 years. Obviously the shorter the payback period, the smaller the return interest needed, and the less costly the total project becomes. For a 10 year period payback we can assume that growth in this corridor will not significantly increase (let’s assume on average over this 10 years the total users rise to 10,000 residents or 20,000 crossings daily). Let’s also be nice to the numbers and assume Virginia will help out the loyal GOP and wealthy residents of Loudoun county with a sizeable $500 million assistance. This leaves $4.5 billion that must be done through toll backed bonds. We’ll be generous again and say that even on weekends there will be 20,000 crossings. So how much would a Greenway like toll of 4 dollars generate over 10 years? Right around 300 million dollars. Are you starting to see the problem? There just isn’t enough actual users to fund a project that would be so costly, it is an entire order of magnitude short of its funding needs and last I checked no one would pay a 40 dollar toll to cross a bridge, no matter how nice of a route it would be. Ok well how about a 50 year backing? Well this is tricky, you are gaining the benefit of more time, but you must also pay back far greater in the long run. For instance even with the historically low interest rates today on houses, a 30 year mortgage
at the end of the term will have cost over 2 times the actual cost of the house. The more money you have up front, and the shorter your term, the less total cost. Let’s assume the bonds are backed with a private company that sees some great potential of the corridor (though unlike 495 HOT this is not a likely scenario) and let’s say the total payback cost of the toll users will only need to increase 10% in this 50 year life span (right around $5 billion total). PAGE 12
Let’s help out the numbers more, since 50 years is a long time (something that people who are against the cost of urbanizing Fairfax infrastructure don’t understand). Over the course of 50 years let’s assume a steady inflation of 3%. That would mean that the Greenway toll 50 years from now would be the same cost as today (4 dollars) if it were priced at 9 dollars. This is just inflation, nothing to be afraid of, it is the reason why a hamburger no longer costs 10 cents and is the natural progression of an economy that is experience growth (something that everyone wants). So over that 50 years the actual average toll intake is closer to 6.50 cents if it were priced similarly to the Greenway. One final assumption, let’s say that Loudoun county becomes a better place because of this corridor and 20,000 crossings becomes 60,000 crossings over that 50 years. On average again this would be a typical
crossing rate of 40,000 trips per day. Again these assumptions are all very ambitious and favor a bridge crossing very aggressively. The amount of revenue generated from the tolls would therefore be 4.7 billion dollars, 300 million dollars short but at least most of the way there. Therefore a toll rate of about $4.50 which would rise with inflation to about $9.50 in 50 years could theoretically work. This unfortunately assumes explosive growth of 300% in that same time as well as 365 days of steady toll user ship. It also assumes that Loudoun County lands the deal of the century with a private partner who will only require a 10% total payback over cost. That means only a 0.2% annual yield on the investment while taking on a multi-billion dollar risk. In reality any private partnership would need to see back at least a
100% payback over 50 years, closer to a 2% margin annually, which would force the tolls to be far greater to pay off the in total 9 billion dollar project. This project as it is currently proposed simply does not make sense. There is no private interest either from the construction and management aspect or from the commercial business aspect (special tax districts). As it did over the past 20 years this ghost dream of an outer beltway crossing of the Potomac will once again die away once actual numbers are put behind it, but in the meanwhile it is distracting the true discussion. This area DOES need another bridge crossing of the Potomac and it needs to function for both vehicles and rail expansion. In our follow up article we are going to talk about how it can be done, and where it should go to do the most benefit and be the most economical and functional siting. PAGE 13
The of Traffic Hydraulics In hydraulics the flow of water is classified using a Reynolds number. This is a constructed variable which weighs the impact of a flowâ€™s velocity and composition and the material of the conveyance pipe in order to determine a friction factor. Click. Click. Click. I just wanna read about food trucks and new buildings. I promise this is getting somewhere. The friction factor is an important variable in flow parameters. It defines how much energy is lost when a fluid goes through a pipe or any valve, tee, cross, bend, etc. When a flow begins to slow down, dwindle, or otherwise convert from a supercritical to subcritical flow (sudden hydraulic jump) it is directly attributable to the loss of
energy. The reason why water from a reservoir 20 miles away eventually comes out of your shower head with adequate pressure is because the network that conveys this water is adequately designed.
What makes water flow into one pipe at a certain rate and through another pipe at a different rate? Is it all dependent on the size of the pipe? Not quite, in a pipe network the amount of flow does not find equilibrium based on a pipe size/flow ratio but rather all pipes in a network and paths will find equilibrium in how much friction energy loss they experience. This is important because this is the mechanism in which water determines what its direction of least resistance is. Now we come to transportation networks. The current method for determining how well a network is operating and how well an
improvement will work views the network as several independent objects which direct flow based on their capacity. This is materially flawed because it does not understand that when a new highway improvement is completed users that used to find the friction energy (congestion) with that route to be slightly more than an alternate route will now make a decision whether the new improved path is now better.
This is induced traffic, something that transportation models still canâ€™t anticipate. Because each road user is very similar to each unit mass of water it is not a large leap to view this dynamic similarly. Therefore, instead of viewing a network based on capacity and route widenings, each network improvement should be analyzed to determine the new equilibrium friction factor. In other words, people like water will follow a path of least resistance. PAGE 16
By creating an appropriate mathematical model the network designer can also analyze the system not only at a point and place peak, but at any time and geography of the day. This will help solve the issue of over sized roads, if properly done, which go completely under used for a majority of a day.
In fluids the energy in a system is defined as; Total Energy = Potential Energy(gravitational energy) + Kinetic Energy (movement energy) + Dynamic Energy (pressure energy) â€“ Friction Loss (energy loss from point A to B) Potential energy has no real implication in traffic flow as the elevation has no sizable impact on transportation network operation. Kinetic and dynamic energy however are very relevant to transportation analysis. The velocity of vehicle travel will directly increase the total quantity and capacity of the road and, as in fluids, will increase the impedance friction that occurs. Why? At faster velocities traffic has more difficult stopping and accelerating, similar to fluids, and gaps between each user is increased. Dynamic energy becomes an interesting question. In fluid flow it defines the characteristics of the fluid that is in motion and the pressure energy contained with in it. In a transportation setting this dynamic is similar to the composition of the vehicles within a traffic flow and a measure of the traffics linear or chaotic nature. If users are continuously shifting in and out of lanes due to multiple point exits and entrances then the relative capacity and friction caused is effected compared to a traffic flow in which everyone remains in their lanes. This has a huge implication on how effective a system is in moving users. With this definition we can now view Bernoulliâ€™s fluid equation in terms of transportation; Total Energy = (v^2)/2 + (chaotic flow factor/static factor) â€“ Friction Loss between two points The total energy is important to understand as it will indicate when a traffic flow will go from supercritical (free flow) to subcritical (congested flow) patterns. Before we delve into that issue we must understand the friction loss and the variables that turn a stable flow into a deteriorating flow. It is also important to understand friction loss as this is the element which all travel ways/paths within a system will form equilibrium to, not capacity.
People, like fluids, will choose the path of least resistance. Not just how far they have to travel, but how long it will take.
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Congestion Energy Losses and
Network Equilibrium The path of least resistance in water was related to individual users determining their own best path from point A to point B. In our next step we need to examine what factors in transportation will have an impact on congestion energy loss. The loss of energy in a fluid conveyance is governed by the Darcy-Weisbach equation where; Energy loss = f (L/D) x (v^2/2g) In this equation we see the friction factor, as discussed in part 2 of our analysis, as a function of the length (L) and size (D) of the system, being linearly related to the energy loss. Conversely velocity (v) has an exponential impact on how much loss is experienced in the system. When determining the friction factor in transportation we find that Moodyâ€™s diagram, converted to apply to transportation, shows an inverse relationship between the
Reynolds number and the friction factor. Therefore the friction factor rises as a flow becomes fully turbulent. What does this mean? We should slow down roads to a design speed of 25 mph? No. As we see by the basic capacity equation (Flow= velocity x area) the velocity of a system, while causing significant energy loss, also has huge impacts on the actual flow volume possible on a road. What this does say however is, in areas with turbulent characteristics in traffic flow (lane movements, high speeds, variant user types) and with high speeds we see a very sudden deterioration in a roads capacity from visibly functioning to full traffic jam. While increasing the number of lanes (the diameter/area) does increase the capacity of the road, it only affects the energy loss linearly, while other factors are impacting the system exponentially. For this reason by attacking the systemâ€™s demand, and therefore its turbulence, the energy loss is impacted far greater and more efficiently. The best method to reducing demand is providing an alternate
path. This of course needs to be balanced with cost, negative results of new traffic patterns in previously unused regions, and the need for some corridors to be improved with mass transit. In piped networks where a long and over capacity section often times is improved by creating a loop to its destination. This allows demand to be split by these two paths and is far more efficient than increasing the size of the pipe in question in many cases. This is visibly the case in transportation networks as well, where often traffic within a city finds a healthier equilibrium in the gridded network than the freeways with fewer route options. Whether the system is improved via a new route connection or increased corridor size, the effect is not experienced solely on the direct vicinity. The entire network re-adjusts to find a new equilibrium based on all congestion energy losses being equal at any multi direction option. The new pathway will induce traffic flow from congested routes to the new lane/road.
In a simple example, imagine 3 suburban regions with paths into an urban core. The regions themselves are connected to each other, as well as the commercial business area. If path 2 did not exist, then the users from the outer suburb would either choose path 3 or path 1, and that decision would be dependent on how long it takes for them to get to work, not on how much capacity either route is capable of. In this way, the length and congestion is the largest determinant in how the flow will split. If very few people use path 3, even if it is a longer route, the two roads will find an equilibrium in which the statistical average of users will balance their commute path timing.
If a new path 2 was constructed between two of the suburban regions one could expect that a significant amount of people from
path 1 and path 3 would now switch to using path 2. At a certain point this may mean that path 2 deteriorates by overuse, causing larger congestion energy loss, and therefore path 1 and 3 would still be used by some. Again the length of time it would take for the statistical average of people would determine how much each path actually receives. If the final segment of path 2 and 3 was in very poor condition then people would still use path 1 to a level in which the length of time it would take to use path 2 or 3 would equal out. If the final portion of path 2 and 3 was really awful, everyone from suburb X could end up using path 1. However EVERYONE will not switch to path 1, because if this were to occur then path 2 and 3 would suddenly become far more attractive of a route.
Stuck in the Middle With You McLean Virginia has come to be defined by its upscale residents, a culture of isolationist development, and an objection to all outside ideas. For all of the wealth its residents possess the town is beginning to show some wear and tear. After decades of rejecting almost all centralized concepts and master planning over hauls the main corridors of Dolley Madison and Old Dominion have gone from vibrant destinations to aging to through ways. McLean has an opportunity with its location tucked between Tysons Corner, Arlington, and Northwest DC in becoming a boutique sleeping community with more than tract housing without needing to â€œurbanizeâ€?. In a twitter discussion between myself and Richard Florida this past week, (640 characters of amazing conversation), I came to realize that density is not always a way forward. Sometimes the best way to create smart growth in a region is to understand its culture and the desires of residents to preserve the neighborhood. Integrating subdued growth in a way that can create benefits to residents through better walking corridors, lessened traffic, and diverse retail can organically create a main street.
In previous stories we have said how important reinstating main street to our towns really is, by creating ownership of the town instead of mass selling of lands to large retail stores, everyone is reinvested in the future. No one cleans up a neighborhood better than its own residents, but when that resident becomes a multi-national corporation, the neighborhood becomes entrapped by an absentee landlord.
Dolley Madison Drive may be too far gone to save, this road has clearly become a traffic calmed vehicle corridor. Old Dominion on the other hand still has a chance. Every year the traffic counts on Old Dominion continue to grow and of course much of this is commuter traffic using Old Dominion as a go between from the Dulles Toll Road and Arlington.
In order to save 4 or 5 minutes on a commute users are opting for this route as opposed to using Route 123 to GW Parkway, a more appropriate vehicular path. With this excessive through traffic the corridor has fallen to the retail cycle of strip malls and gas stations. There have been some spot improvements such as the Elm Street development however this is only a fraction of the remaining corridor between Chain Bridge Road and Dolley Madison. How can Old Dominion be taken away from commuters and returned to residents?
Most bike incidents occur at intersections or by drivers who refuse to give equal right of way to bicyclists. Bike lanes are tough political sales, often expensive for Right of way acquisition, and continue a cycle of widened roads.
Start with traffic calming, let users who want to fly down Old Dominion at 45 miles per hour know that they are no longer the priority. One concept could be including roundabouts at Old Dominion and Chain Bridge, but an easier sale might be right lane rumble strips that create an inherent bike lane. The rumble strips do nothing to impede vehicular traffic (much smaller than speed bumps), but by providing 4 or 5 strips tightly together every 200′ a vehicle becomes annoyed by the cadence of the lane and is more likely to use the left lane. At a minimum most people don’t enjoy driving 45 mph over rumble strips and would choose to slow down to the actual speed limit of 35 mph.
A mixture of traffic calming on specific corridors like Old Dominion, where through traffic is unwanted, with rumble strips can return huge benefits and make pedestrian and bike travel safer without large capital costs by using existing road space.
The ripple effect would be more users selection GW Parkway and more short trip users (residents) being able to use their own roads with either cars, bikes, or walking and being able to do so safely. This is cost effective (extremely low cost as opposed to adding more paved surface) and keeps Old Dominion at a manageable and attractive human scale. Next step? Allow some redevelopment in this specific region for higher end retail, projects that are willing to build structural parking so that shops can be brought forward and along wider pedestrian walks. Require small scale (15′x15′) parks for every block to encourage pedestrians. These are small tweaks without
needing skyscrapers, that are affordable and not obstructive to developers, and are encouraged with the small improvements within public areas like the streets. Why do this? The people of McLean like their area the way it is and it has always been this way. Actually, McLean wasn’t always this way. It started as a township incorporated into the W O&D Railway. The town original looked as you would think, a small hamlet of 19th century brick buildings, tightly wrapping this commercial center, and surrounded with wealthy homes and manors.
The only remaining semblance of its past remains the wealthy homes, but with all that wealth the residents have lost a sense of identity that other towns like Vienna or Old Town Alexandria retained. This is visible by just how few residents you see walking around what remains of this corridor, heck you barely see anyone driving and parking unless you are talking about the McDonalds on the corner which is packed. To say that residents don’t want a sense of community and place is a hyperbole of what suburbanites want. Yes obviously residents want to keep their houses unimpeded with skyscrapers and traffic, but when did they demand that stores must only remain Stop N’ Go and 7-11. Clearly there are other options as well but even these businesses have trouble, see the closure of McLean 1910, because of the lack of a unified and accessible path for residents. By returning to what made McLean an affluent corridor and town, without mimicking what Arlington and Tysons are doing, the residents can have both their wealthy hamlet and an outlet to enjoy the smaller things in life. This doesn’t require adding hundreds of thousands of square feet of retail space, it means adding smartly designed and compact development which spurs a mom and pop format. It won’t happen all at once, but speaking with one voice and vision for the town can resist development in the form of McMansions and strip malls, and encourage tried and true methods that have lasted multiple generations like in Old Town Alexandria and Vienna