Transportation Network: Coordinated vs Anarchy

Recently I wrote an article for Paradox (Melbourne University Maths and Stats  society's magazine). It can be found on page 21-24 on this issue. Below are the first few paragraphs.

In the "real" world, many systems can be characterised by a network with nodes and paths joining them. Here, we will consider traffic flows of a decentralised transport system for personalised vehicles. It is natural to ask ourselves whether or not this network system is the most efficient one, alternatively, on average, does this road network allows commuters to get from A to B most efficiently?

On the surface, this question seems easy to answer; one can

• set up a model of the system;
• find the global minimum using the convex minimum cost flow algorithm.  

In reality, individual commuters do not collectively opt for the most optimal strategy, but their own optimal strategy. Hence, the actual performance of the network is often far from its best, even if all individuals choose the quickest route and all information is available to them. The key question here is to understand how far the actual performance is from the most optimal one. 

Part 2

The second idea is bus rapid transit.

Unlike conventional bus system, BRT is its new interpretation. It has most of advantages of train system without its cost. There are no complete agreement on what constitutes as BRT, but to me the following rough idea will explain what I believe to be BRT.

Walter Hook, director of the Institute of Transportation and Development Policy, measures the success of BRT by whether or not commuters identify BRT as permanent structure within city on part with trains and trams. Let me explain further. When we think of train, we immediately think of its stations and rail tracks. In Melbourne, we will probably think of a system under severe stress. Similarly, when we think of trams, we think of rigid tracks that run with automobiles, sometimes in complete separation from the main traffics. And in recent time, platform stops around CBD.  So, when I say that BRT's success is measured by comparing with trains and trams, I mean that Melway includes all of BRT infrastructures in its publication. 

So, what elements can combined to form BRT? 

First, its stations must be distinct from normal bus stops. In most implementation, this entails a raised platform, where the floor of station is level with the bus floor. I believe this is not necessary enough. A well-designed stations are generally enclosed and provide pre-paid ticket system. This allows the commuters to purchase ticket prior to the bus entry and thus reduces the time waste at each stop. Now, the main problem with this system is that conductors are required at each station, and hence increasing the operating cost. In addition, some stations can be designed to be local landmarks within suburbs like New York subway mosaic.

Second, the bus must be distinct from the conventional bus. Commuters cannot distinct the difference between normal bus from BRT if the BRT fleet is essentially the same as bus fleet. That is, there is no point in running BRT with old rundown buses. So what should be included in the new bus? The bus should be fitted with two wide rear and front doors to facilitate large flow of commuters. I am sure that there are more innovation out there.

Third, in some system, its buses run on separate lane. Note that this is not essential elements, depending on the condition of the local traffics. The philosophy is that the bus must be able to navigate through without interruption. So, in low traffics condition, often the mixed used lane is sufficient. In contrast, in dense traffic like Hoddle st during peak hour, separate bus lane is crucial to the success of BRT. For example, an ideal design may reserve two lanes for BRT buses and local buses. This may be physically separated like the proposal for New York.

Further within close proximity of the station, some street furniture is required. What makes train station distinctive is all the local street furniture associated with it. It is simply not enough to just put a station and expect it to do a trick. For intuition, pedestrian crossing and walkable street with cafes maybe added to create unique culture around the station. This is something bus stop or highway can never achieve. 

Advantages

1. Cheap per mile in comparison with train and tram.
2. Easy to implement. In general, the route should coincide with the one with high bus usage. 
3. High frequency.
4. Express service means faster transportation.

Disadvantages

1. In the face of climate change, it is harder to change the bus fleet to something carbon neutral.
2. Addition of the bus on the road means higher road maintenance cost.

  For example of well implemented system see TranMilenio in Bogota, Colombia.

New ways to move people around

In recent months, Melburnians have noticed and some experienced the train system under tremendous strain as a result of years of neglect. It is logical that the government should therefore implement effective transportation plan, which can reduce the strain in the current system for a reasonable price.

On this weekend, I found two reasonably new ideas of moving people around. One is significantly cooler than the other. I will talk about the cooler one first.

CyberTran : The problem with the current rail system is that the train has to stop at every stations it was scheduled. As a consequence, from commuter perspective, if he want to travel pass 10 stations, the train has to stop unnecessarily at 9 stations. From this perspective, we see that the current form of urban rail is inefficient. Since societies compete by the speed at which information/capital flows though the city (in this case, human capital), inefficiency in public transportation means losing competitive edge.

I believe that CyberTran can reduce this inefficiency. First let me explain what is CyberTran, then the potential benefits of CyberTran.

CyberTran is a complete transportation infrastructure which consists of the vehicle (called tran), the guideway and station. It doesn't have a schedule like conventional train. The commuters select their destinations and after waiting for a short period of time, the vehicle will pick them up and take the passengers directly to the destination without stopping at stations in between.  

On the contrary to convention wisdom in public transport, tran is a computer-controlled ultra-lightweight train which can carry at most 20 people at any given time. If there are more than 20 people wanting to go to the same destination, then more trans will keep coming until all passengers have been picked up. Since tran is always stored in the station when it is not in used, the waiting time is generally short. 

Trans run on separate guideway. One advantage of lightness of tran is that less structure components are required to build the guideway. This has a benefit of lowering initial cost of construction and allows the guideway to be completely built - with similar cost - where it has less interference with other form of traffics. 

The stations are designed so that trans can bypass them without interfering with stationary trans there. Hence, they are located off the main guideway. This increases the average speed since other cars don't have to slow down. Further, since most energy is spent on accelerating and decelerating vehicle, by maintaining cars at near constant speed, one can achieve higher energy efficiency. 

The unused trans are stored at the station and can be recharged using solar cell (or other appropriate form of renewable energy). Therefore, it has an additional benefit which is; no large warehouse is needed to store vehicles. 

Once passengers are picked up, tran will accelerate to the speed before joining the main guideway. As the vehicle is controlled by computer, there is less chance of collision. This is demonstrated in Morgantown PRT system in West Virginia, where excellent record was maintained during its 30 years in operation. 

Its advantages:

1. Safe with low level of collision.
2. Lightness of vehicle means less is needed for construction of the guideway.
3. It uses less energy to move similar population than the conventional train with regenerative braking system in place. 
4. With virtually no stopping in between stations (it can be designs by some clever algorithm to stop at a few stations.), it can achieve higher speed. 
5. It costs less than train system to build and operate.
6. Less polution.
7. Increase commuter travelling freedom, and less stressful.
8. Tran can travel on the slope of up to 20% in comparison with 5% for train. This means it can navigate through obstacles more easily than train. 

All in all, I like this idea. The next one is bus rapid transit. In considering for construct more study is needed. But in term of pollution, CyberTran has more potential to be carbon-free during its operation.

Here is a video of similar idea.