Showing papers on "Traffic wave published in 1971"

An Extended Traffic Assignment Model with Applications to Two-Way Traffic

Abstract: A transportation network is considered. The traffic demands associated with pairs of nodes and the traveling cost functions associated with the links are assumed given. An extended traffic assignment model where the traveling cost on a link becomes a function of the entire flow pattern in the network is introduced. The model appears particularly suitable for application to networks containing two-way streets, in view of its capability of taking into account delays to travelers of one lane caused by traffic on the opposite lane. It is also suitable for application to urban transportation networks, where the travel time on a link depends crucially on the delays occurring at the intersections. This in turn depends on the traffic volumes on the intersecting links. The concepts of system-optimizing and user-optimizing traffic patterns are studied. Moreover, an algorithm for the construction of the above patterns is presented and applied in an example.

Some traffic parameters at signalized intersections

Abstract: FUNCTIONS THAT ARE USEFUL FOR THE EFFECTIVE DESIGN OF TRAFFIC SIGNAL TIMING ARE DEVELOPED. INTERSECTION CAPACITY IS A FUNCTION OF STARTING DELAY AND VEHICLE SPACING, FOR WHICH SPECIFIC MEASURES ARE GIVEN. EQUIVALENCIES FOR TRUCK TURNING, FOR RIGHT TURNING, AND FOR OPPOSING LEFT TURNING VEHICLES WERE MEASURED FOR COMPARISON TO THE ABOVE HIGHWAY PARAMETERS. AN EXPRESSION FOR AMBER USED EFFECTIVELY AS GREEN IS DERIVED, AS A FUNCTION OF APPROACH SPEED.

Time headway distribution of traffic flow

Abstract: Arrival distribution of vehicles is one of the basic characteristics of traffic flow. Since average time headway is inversely proportional to the traffic volume it has been considered as an approach of the study of traffic capacity. Arrival distribution is essential to deal with the traffic flow stochastically in the problems such as queing problems of crossing or merging traffic, and various traffic simulation.The paper deals mainly with congested traffic flow which causes so many traffic problems. The objects of this study is to obtain and analyse the characteristics of actual traffic headway distributions and to find theoretical distribution models which fit well to them.Several field observations were carried out and a theoretical distribution of traffic headway is proposed based on the observed data. The theoretical distribution fits very well to the actual ones.

On optimal ramp control of traffic jam queues

Abstract: Figure 1 depicts two parallel roads, one "fast" and the other "slow", with a ramp on which vehicles from the slow roadway may be allowed to merge onto the fast road. Such a situation occurs frequently when a freeway or expressway is accompanied by a service road. It seems reasonable to restrict the ramp flow when an accident or congestion has caused a traffic jam downstream from the ramp. The traffic jam will then clear up more quickly, at the expense of inconvenience to a few vehicles which must continue travelling on the slow road instead of entering the fast road. This policy is especially valid if the fast road has more high priority vehicles, e.g., buses.

Real-time computer control of highway traffic

Abstract: The growing traffic congestion on national highways requires an increase in utilizing automarion in traffic control. One of the possibilities of improving the efficiency of controlling large stretches of highways is by using real-time computer control. Monitoring and sensing devices would be introduced and placed along a highway at selected places. One of the possible values to be measured is the cumulative count of vehicles at a certain place. This cumulative count should be recorded along with the appropriate real time. With this information on record, the flow rate and vehicle density at specific locations of the highway and at specific times, could be readily calculated. The data measured along the highway are transmitted to a central computer system and recorded in memory along with the appropriate times and places. The computations of flow rates, densities and other items that may be required, are performed by the same computer. A model representing the dynamics of the traffic flow will be adopted. Several possible models have already been proposed in the past. In the adopted model the vehicle flow rates, densities and velocities, will be connected by linearized difference equations which will serve as constraints in the optimization problems that will evolve. The equations representing the model (or several models available optionally) will be programmed and stored in the central computer. The equations will include the on- and off- ramp flow rates, which will constitute the control variables in many cases.

Vehicular Traffic Flow Theory and Tunnel Traffic Flow Measurements

Abstract: VEHICULAR TRAFFIC FLOW HAS BEEN INVESTIGATED THEORETICALLY AND EXPERIMENTALLY IN ORDER THAT PEAK HOUR COLLECTIVE TRAFFIC FLOW DYNAMICS CAN BE UNDERSTOOD AND THAT THE PEAK HOUR FLOW THROUGH THE CALLAHAN TUNNEL CAN BE IMPROVED BY MEANS OF TRAFFIC FLOW CONTROL AND MODIFICATION. TWO THEORETICAL MODELS ARE SUGGESTED, THE FINITE REACTION TIME MODEL AND THE ASYMMETRICAL RESPONSE MODEL, AS PREDICTIVE OF OBSERVED TRAFFIC DENSITY DYNAMICS, WAVE GROWTH, AND ASYMMETRY. EXPERIMENTALLY, A TRAFFIC FLOW PROFILE OF CAPACITIES, VEHICLE SPEEDS, AND TRAFFIC DENSITIES IN THE CALLAHAN TUNNEL HAS BEEN OBTAINED, AND RELATIONSHIPS BETWEEN SLOWDOWN WAVE PHENOMENA AND TRAFFIC FLOW, DETERMINED. BASED ON THESE, IT IS SUGGESTED THAT TRAFFIC FLOW MAY BE IMPROVED WITH TRAFFIC FLOW MODIFICATION PROCEDURES. /NTIS/