Some Theoretical Aspects of Car Trips within Urban Area

OD trips in urban area are described by an ergodic Markov chain for each kind of car and have a certain steady pattern for each trip. The pattern of OD trips is effected by the total number of cars independently of initial distribution of registered cars and strongly by the transition probabilities from zone to zone and their limiting vector. The limiting vector make a display of potentiality of generating trips for each kind of car. In estimating future traffic volume, it plays an important role in determination of the pattern of car trips, because the limiting vector is given by land use planning. Transition probabilities are introduced from maximizing entropy per unit time under the fixed limiting vector. Thus OD trips in the future are easily estimated, using the transition probabilities. It is proved that car trips estimated by maximizing entropy are symmetrical

A Safety Index for Traffic with Linear Spacings

The authors have tried to improve the traffic dynamic theory of Prof. Pipes and have found the fundamental equation of traffic dynamics for a case in which the velocity of the following vehicle is determined not only by the space between following and lead cars but also by the velocity of the lead car. The safety of the following car with respect to rear end collision when the lead car is in sinusoidal motion is quantified by introducing a safety index. At the same time, the authors describe the stability of the indicial response of the following car, and the stability of the propagation of a sinusoidal disturbance down a line of cars

The Development of Trip Chaining Approaches in Travel Demand Modelling

The purpose of this paper is to incorporate trip chaining into travel demand analysis, and also to develop a model for an estimation of trip generation. Before the discussion on the model formulation, a brief historical review of trip chaining approaches is presented, and some validations of those approaches are explored. The model proposed here is able to explain the derived nature of travel demand due to various kinds of business activities in a metropolitan area. One particular concern is to describe the cycle-sojourn zone distribution, which plays an important role for generating a sequence of business trips. In this model, the cycle-sojourn zone distribution is formulated by applying an entropy maximizing distribution model of the gravity type. From its application, it can be found that this model is useful for representing business trip chaining behaviours in a single day

Analysis of the Image for Landscape of Port City

The purpose of this study is to obtain basic information available to make a new design concept at the first stage of landscape planning. Recently, with the large change of waterfront spaces, urban environments around port cities are getting more serious in Japan. So it is nesessary to begin planning to recreate the landscapes and facilities. However in this case we should consider the people's image and impression on curtural climate or environments to make fascinating townscapes. We sconsider two positions of people's image denned. One is the Media Image, and the other is the Residents' Image. Many current topics on tourist resorts or fascinating landscapes have been usually reported by visual and linguistic mass media in Japan. Many people form their images on townscapes without real experience. This image is called the Media Image and represents the external people's hope for spaces. On the other hand, the internal residents in the port city form their image by real experience or influence on their lives. This image is defined as the Residents' Image. Through a psychological experiment under the stimulus of visual media, this study specifies basic characteristics of the visual landscapes at representative port cities in Japan by comparing the two images

Estimating Time-Varying Origin-Destination Flows from Link Traffic Counts

A dynamic model for estimating real-time origin-destination flows from time-series of traffic counts is presented. The time variation of flows is explicitly treated as a dynamic process. The model is formulated based on minimizing the integrated squared error between predicted and observed output traffic counts over the period of observation. An efficient solution method is developed by using Fourier transformation and illustrated with numerical examples. The numerical simulation experiment shows that the system dynamic approach may be particularly suitable for on-line traffic management and control in urban transportation systems

A Road Network Design Model Considering Node Capacity

Optimal road network design models have been investigated in order to generate alternatives of road network planning. Most of the previous works assume that the decision variables of the planners are the attributes of the links. The actual road network, however, consists of links and nodes, and it is useful to distinguish links and nodes explicitly. Planning models should involve the attributes of nodes in decision variables as well as the link attributes. We formulate a road network design model considering the nodal capacity. The frame of the proposed model is interpreted as a two level optimal problem, which is a system optimizing problem including an optimal problem as its constraint. Before the formulation of a two level problem, the structure of a node is simplified, and a nodal passing time function is introduced, which represents the performance of a node. As a user equilibrium is the most relevant assumption for the description of road network flow, the lower problem is formulated as a fixed demand user equilibrium problem, using nodal passing time functions as well as link travel time functions. Given the total investment cost constraint, the higher problem decides the link and nodal capacities in order to optimize a measure of the whole network performance. The lower problem describes the traffic flow on a network for given capacities. The structure of the model is explained by using the frame of the Stackelberg differential game, whose players are planner (leader) and aggregate term of network user (follower). In order to solve the formulated problem, a heuristic algorithm is proposed. This is the input/outputiterativemethod, and it is expected to be effective for a normal size problem. The convergence of the algorithm is numerically confirmed through an example for simple and hypothetical datum. A sensitivity analysis for the value of the cost constraint is executed to determine the effective value of an investment. Remaining problems are extensively discussed for further research

Traffic Flow on Urban Networks with Fuzzy Information

Many methods of analysis of traffic on transport networks have been proposed which assume crisp travel time. Most of them are based on Wardrop's principle which says in particular “"The travel time on all routes actually used equal to and no greater than those which would be experienced by a single vehicle on any unused route.”" The principle represents a state of user equilibrium under the condition that drivers can get perfect traffic information. Though this principle reflects the definition of the crisp performance function used in traffic assignment, the drivers dynamically make decisions about route choice behaviour with their experience and given information. A method commonly used to represent such perception is stochastic traffic assignment. In the real world, however, the driver can only use fuzzy traffic information even if several types of information are available. The objective of the study is to formulate the fuzzy user equilibrium with fuzzy travel time and show the application of the techniques to an actual problem. First, a basic survey was carried out to ascertain the perception of drivers on an urban transportation network. The network includes the Hanshin Expressway and urban streets in the Osaka area. In the survey, the travel time for streets and expressways on the same O-D (Origin-Destination) are assumed to be Triangular Fuzzy Numbers (TFN). A TFN is simply defined as (Tl, To, Tr) which show the smallest value, centre of time values, and largest value respectively according to the perceived travel time T. Therefore, To is recognized to be an informed and physical travel time. Typical features of perception of travel time are summarized from the survey results. The membership function of the fuzzy number on travel time can be displayed once this database is constructed from the empirical survey. Second, the descriptive method of route choice behaviour is introduced to design the traffic assignment model. The crisp travel time for link a, Ta, is extended to fuzzy number TFa with the spread parameters described above. Two concepts of comparison among fuzzy travel times are introduced. They are the centre of gravity method and the generalized distance method based on compatibility. The former is the very simple concept that the centre of gravity point of a fuzzy number is adopted as a representative value of TFa. The latter method is based on the α-cut concept of fuzzy sets. The definition of generalized distance between fuzzy numbers is defined as the sum of successive intervals between numbers for each a value as it increases from zero to one. It is interesting that with TFNs, this can be carried out rapidly by adding the areas of the triangles in each case. Third, it is assumed that the state of user equilibrium is also generated even if fuzziness of travel time exists. Different results for user equilibrium are observed for conditions of fuzzy information when compared with those obtained under conditions of prefect information. In other words, the link performance function is extended in view of the concept of fuzzy numbers. In particular, the extension principle of fuzzy numbers allows that the comparison methods mentioned above are also valid when fuzzy travel time is applied on the route. Therefore, the fuzzified user equilibrium assignment model can be proposed with these concepts. In this section, the Fuzzified Frank-Wolfe(FFW) algorithm is introduced to obtain a fuzzy optimal solution as the solution of a conventional problem. In changing the algorithm, the modification is only to replace the crisp value of the travel time function t(x) with the representative values of the fuzzy travel time function tF(x). The fuzzified algorithm, therefore, is easily derived from a simple extension of the conventional algorithm. The results of a numerical example are presented to consider the stability of the algorithm. Different results of user equilibrium are observed when compared with those obtained under conditions of information. The relation between the width of the fuzzy travel time distribution and traffic flow is estimated on each link. It is observed that the user equilibrium flows shift according to the fuzzified link performance function. It is also mentioned that the idea can be applied to produce Fuzzy Incremental Assignment (FIA). Fourth, the application of the proposed method to a realistic problem is discussed. The information given to the drivers seems to change their perception of link travel time. In particular, this fact is usually observed when the change of the perceived width of fuzzy numbers according to the travel time information in TFN has an impact on the traffic flow on networks. Because the different definition of left and right spreads of travel time represents the change in human perception under different conditions of information, the impact can be evaluated as a change in traffic volume on the network. In conclusion, the relationship between information and traffic flow can be described by the proposed method. It becomes obvious that the traffic equilibrium flow changes according to traffic information which is available to the drivers. The results of traffic flow analysis under fuzzy information, therefore, become useful for the discussion of a future traffic information system

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Multi-messenger Observations of a Binary Neutron Star Merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ∼ 1.7 {{s}} with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of {40}-8+8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 {M}ȯ . An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ∼ 40 {{Mpc}}) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ∼ 9 and ∼ 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.</p

高速道路橋脚へのツタの植生に関する景観評価

1999年度土木学会関西支部年講演会にて一部発