Transportation mode recognition using GPS and accelerometer data


One of the big problems for smartphone travel diary apps is automatic mode detection. The split between walking and not is pretty easy, as is cycling, but what about separating cars from rail? Apps like Moves just dubs it "transport", but that doesn't help much with travel behavior research. A new paper in Transportarion Researc Part C examines using accelerometers and GPS to detect mode. Tao Feng and Harry J.P. Timmermans from Eindhoven University of Technology present their research in, "Transportation mode recognition using GPS and accelerometer data"

Potential advantages of global positioning systems (GPS) in collecting travel behavior data have been discussed in several publications and evidenced in many recent studies. Most applications depend on GPS information only. However, transportation mode detection that relies only on GPS information may be erroneous due to variance in device performance and settings, and the environment in which measurements are made. Accelerometers, being used mainly for identifying peoples’ physical activities, may offer new opportunities as these devices record data independent of exterior contexts. The purpose of this paper is therefore to examine the merits of employing accelerometer data in combination with GPS data in transportation mode identification. Three approaches (GPS data only, accelerometer data only and a combination of both accelerometer and GPS data) are examined. A Bayesian Belief Network model is used to infer transportation modes and activity episodes simultaneously. Results show that the use of accelerometer data can make a substantial contribution to successful imputation of transportation mode. The accelerometer only approach outperforms the GPS only approach in terms of the predictive accuracy. The approach which combines GPS and accelerometer data yields the best performance.

The full article can be found here

Ant colony routing for Freeways

ants all in it

Do we drive like ants? Researchers from TU Delft's Center for Systems and Control use an ant routing algorithm for freeways. "Ant Colony Routing algorithm for freeway networks" by Zhe Cong, Bart De Schutter and Robert Babuška, explore this topic. 

Dynamic traffic routing refers to the process of (re)directing vehicles at junctions in a traffic network according to the evolving traffic conditions. The traffic management center can determine desired routes for drivers in order to optimize the performance of the traffic network by dynamic traffic routing. However, a traffic network may have thousands of links and nodes, resulting in a large-scale and computationally complex non-linear, non-convex optimization problem. To solve this problem, Ant Colony Optimization (ACO) is chosen as the optimization method in this paper because of its powerful optimization heuristic for combinatorial optimization problems. ACO is implemented online to determine the control signal – i.e., the splitting rates at each node. However, using standard ACO for traffic routing is characterized by four main disadvantages: 1. traffic flows for different origins and destinations cannot be distinguished; 2. all ants may converge to one route, causing congestion; 3. constraints cannot be taken into account; and 4. neither can dynamic link costs. These problems are addressed by adopting a novel ACO algorithm with stench pheromone and with colored ants, called Ant Colony Routing (ACR). Using the stench pheromone, the ACR algorithm can distribute the vehicles over the traffic network with less or no traffic congestion, as well as reduce the number of vehicles near some sensitive zones, such as hospitals and schools. With colored ants, the traffic flows for multiple origins and destinations can be represented. The proposed approach is also implemented in a simulation-based case study in the Walcheren area, the Netherlands, illustrating the effectiveness of the approach.

You can find the full article here

Book of the Week: The World Beyond The Windshield


Anybody who has gone on a roadtrip has experienced changing landscapes and introductions of new locales through the lense of a windshield. The World Beyond The Windshield: Roads and Landscapes in the United States and Europe is a collection of scholarly papers that examine the relaitonship between roads and landscapes. It touches upon aesthetics, concepts of space, and the evolution of road networks. You can borrow our copy or read it online

Urban Gridlock

Chicago Gridlock

Gridlock is a fact of life in urban areas. Why is that? A new study explores the characteristics of urban gridlock, to better understand the condition and ways to ease congestion. From Transportation Research Part C: Emerging Techonologies, "Urban network gridlock: Theory, characteristics, and dynamics" by Hani S. Mahmassani, Meead Saberi, and Ali Zockaie tackles the issue. 

This study explores the limiting properties of network-wide traffic flow relations under heavily congested conditions in a large-scale complex urban street network; these limiting conditions are emulated in the context of dynamic traffic assignment (DTA) experiments on an actual large network. The primary objectives are to characterize gridlock and understand its dynamics. This study addresses a gap in the literature with regard to the existence of exit flow and recovery period. The one-dimensional theoretical Network Fundamental Diagram (NFD) only represents steady-state behavior and holds only when the inputs change slowly in time and traffic is distributed homogenously in space. Also, it does not describe the hysteretic behavior of the network traffic when a gridlock forms or when network recovers. Thus, a model is proposed to reproduce hysteresis and gridlock when homogeneity and steady-state conditions do not hold. It is conjectured that the network average flow can be approximated as a non-linear function of network average density and variation in link densities. The proposed model is calibrated for the Chicago Central Business District (CBD) network. We also show that complex urban networks with multiple route choices, similar to the idealized network tested previously in the literature, tend to jam at a range of densities that are smaller than the theoretical average network jam density. Also it is demonstrated that networks tend to gridlock in many different ways with different configurations. This study examines how mobility of urban street networks could be improved by managing vehicle accumulation and redistributing network traffic via strategies such as demand management and disseminating real-time traveler information (adaptive driving). This study thus defines and explores some key characteristics and dynamics of urban street network gridlocks including gridlock formation, propagation, recovery, size, etc.

The full paper can be found here.

Bad Moods and Risky Drivers

Road Rage*

There's a new article from Transportation Research Part F that explores a possible link between driver mood and risky driving. Researchers from Peking University's Department of Psychology tested to see how a good or bad mood could affect driving bevaior. From the paper, "Negative or positive? The effect of emotion and mood on risky driving"

This research explored how two states of affect, emotion and mood, would influence driver’s risky driving behavior through risk perception and risk attitude. An experiment and a survey were adopted to test the two paths. In this model, negative affect played an opposite and more powerful role compared to positive affect. Study 1 was an experimental study with four treatment groups. Participants watched one of four video clips (traffic-related negative, traffic-unrelated negative, positive and neutral) and different emotions were induced. Negative emotion significantly elevated drivers’ risk perception but such perception failed to develop an appropriate attitude for drivers. A more favorable risk attitude resulted in increased reports of speeding. Turning from a “point” effect to a similar “period” effect, a survey was carried out in Study 2 to explore the effect of positive and negative mood instead of emotion. Mood states affected drivers’ risky driving behavior through risk perception as well as risk attitude, which was in line with the results of Study 1. The “bad is stronger than good” effect and the two paths in the model were discussed.

The whole paper can be found here

Valuation of Travel Time

Travel Time Map - Department of Transport - MySociety

There a new article in the new journal Economics of Transportation that examines how travel time is valued, how and what is considered, and what should be improved. Kenneth Small's "Valuation of Travel Time"

After decades of study, the value of travel time remains incompletely understood and ripe for further theoretical and empirical investigation. Research has revealed many regularities and connections between willingness to pay for time savings and other economic factors including time of day choice, aversion to unreliability, labor supply, taxation, activity scheduling, intra-household time allocation, and out-of-office productivity. Some of these connections have been addressed through sophisticated modeling, revealing a plethora of reasons for heterogeneity in value of time rooted in behavior at a micro scale. This paper reviews what we know and what we need to know. A recurrent theme is that the value of time for a particular travel movement depends strongly on very specific factors, and that understanding how these factors work will provide new insights into travel behavior and into more general economic choices.

The full article can be found here

The State of Congestion: TTI releases the 2012 Urban Mobility Report


Recently the Texas A&M Transportation Institute released the 2012 Urban Mobility Report. This year's model relies upon a new methodology and expands the coverage, and you can download the data for your city.   The changes give a better picture of issues related to traffic congestion across the United States, as well as historic trends from 1982 to present, though some question if TTI underestimates congestion back them. 

Highway Grants: Roads to Prosperity?

Night Construction II

A new Economic Letter from the Federal Reserve Bank of San Francisco focuses on new research from Sylvain Leduc and Daniel Wilson. From their forthcoming paper, "Roads to Prosperity or Bridges to Nowhere?:Theory and Evidence on the Impact of Public Infrastructure Investment", Leduc and Wilson study the macroeconomic effects of infrastructure investment. 

This research focuses on investment in roads and highways in part because it is the largest component of public infrastructure in the United States. Moreover, the procedures by which federal highway grants are distributed to states help us identify more precisely how transportation spending affects economic activity.

We find that unanticipated increases in highway spending have positive but temporary effects on GSP, both in the short and medium run. The short-run effect is consistent with a traditional Keynesian channel in which output increases because of a rise in aggregate demand, combined with slow-to-adjust prices. In contrast, the positive response of GSP over the medium run is in line with a supply-side effect due to an increase in the economy’s productive capacity.

This research is timley given the prognosis that the Highway Trust Fund will go brankrupt by 2014 all while hoping infrastrcture investment can spur the economy through job creation, as outlined in MAP-21.

More on PPPs and Road Financing

PA Turnpike tilt-shift

Yesterday we talked about Britain's proposed privatization of their transport infrastructre and made an error when we said the Pennsylvania Turnpike was leased to a private company. In 2007 bidding was opened on the Turnpike and in 2008 the highest bid was received from Spanish firm Abertis Infraestructuras, but ultimately the plan failed. Currently the Turnpike is managed by a state-operated commision that "receives no state or federal taxes to operate and maintain its toll road system." The Pew report, Driven by Dollars, outlines several of the problems that were a part of the leasing proposal and calls for a more open process and transparency.

As funding sources dry up, such as the transportation bill now stuck in gridlock on Capitol Hill or depleted state budgets, transportation agencies will have to come up with new methods of financing which has an increasing interest on private money. The 2011 book Road to Renewal examines private investment in transportation projects from around the world, outlining what works and what doesnt for PPPs as well as how to protect public interests. Louise Nelson Dyble has a recently published article "Tolls and Control: The Chicago Skyway and the Pennsylvania Turnpike" which compares the two plans and raises questions about impact on future transportation planning policy.



Privatizing Infrastructure: Leasing Toll Roads

M6 J7 Fireworks

This week Britian's Prime Minister David Cameron gave a speech on infrastructure. He touched upon many different industries and modes, but this is what he said about highways:

Now, road tolling is one option, but we are only considering this for new, not existing capacity.  For example, we’re looking at how improvements to the A14 could be part-funded through tolling.  But we now need to be more ambitious.  We should be asking ourselves, ‘Why is it that other infrastructure’ — for example, water — ‘is funded by private sector capital through privately owned, independently regulated utilities, but roads in Britain still call on the public finances for funding?’ We need to look urgently at the options for getting large-scale private investment into the national roads network; from sovereign wealth funds, from pension funds, from other investors.  That is why I’ve asked the Department for Transport and the Treasury to carry out a feasibility study of new ownership and financing models for the national roads system and to report progress to me in the autumn.  Let me be clear: this is not about mass tolling and, as I’ve said, we’re not tolling existing roads; it’s about getting more out of the money that motorists already pay.

People are already panicking about China owning the motorways, though the BBC does have a nice Q&A about public private partnerships and toll roads. There is also a focus on "shovel-ready" projects, which is apparently concept in the UK. The most famous example of a privitized toll road in Britian currently is the M6 north of Birmingham, which opened in 2003, was proposed by John Major when he was Prime Minister, and is regarded as a mixed success.

These sorts of public private partnerships (PPPs) are quite common in the US. Edit: There was an attempt to lease the Pennsylvania Turnpike, but that failed with lots of lessons learned. The Pew Center on the States wrote an overview of what states and agencies should consider when entering these PPPs. It will be interesting to see how this plays out.

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