PATH

The Cell Transmission Model. Part I: A Simple Dynamic Representation of Highway Traffic

Carlos Daganzo
1993

This paper presents a simple representation of traffic on a highway with a single entrance and exit. The representation can be used to predict traffic's evolution over time and space, including transient phenomena such as the building, propagation and dissipation of queues. The easy-to-solve difference equations used to predict traffic's evolution are shown to be the discrete analog of the differential equations arising from a special case of the hydrodynamic model of traffic flow. The proposed method automatically generates appropriate changes in density at locations where the...

The Cell Transmission Model: Network Traffic

Carlos Daganzo
1994

This paper shows how the evolution of multicommodity traffic flows over complex networks can be predicted over time, based on a simple macroscopic computer representation of traffic flow that is consistent with the kinematic wave theory under all traffic conditions. After a brief review of the basic model for one link, the paper describes how three-legged junctions can be modeled. It then introduces a numerical procedure for networks, assuming that a time-varying origin-destination table is given and that the proportion of turns at every junction is known. These assumptions are reasonable...

Predictability of Time-Dependent Traffic Backups and Other Reproducible Traits in Experimental Highway Data

Smilowitz, Karen
Carlos Daganzo
1999

Traffic data from a 4-mile long congested rural road in Orinda, California, are used to show that traffic delays and vehicle accumulations between any two generic observers located inside a road section can be predicted from the traffic counts measured at the extremes of the section. The traffic model does not require "recalibration" on the day of the experiment, and works well despite what appears to be location-specific driver behavior.

Estimating ATIS Benefits for the Smart Corridor

Raja Sengupta
Hongola, Bruce
1998

This report studies the effects of Advanced Traveler Information Systems (ATIS) on traffic congestion in the Smart Corridor of the Santa Monica Freeway. Simulation modeling is used to estimate the potential travel time savings to divert traffic from the Smart Corridor to arterial roads when incidents occur. The study attempts to establish relationships between traffic management variables, such as incident detection time, incident duration, capacity reduction, percentage of traffic diversion, and duration of traffic diversion.

Diagnosis and Communication in Distributed Systems

Raja Sengupta
1999

This paper discusses diagnosis problems in distributed systems within the context of a language- theoretic discrete event formalism. A distributed system is seen as a system with multiple spatially separated sites with each site having a diagnoser that observes some of the events generated by the system and diagnoses the faults associated with the site. We allow the diagnosers to share information by sending messages to each other. Distributed systems are classified as being centrally, decentrally, and independently diagnosable. We characterize the class of distributed systems for which...

Fault Diagnosis for Intra-platoon Communications

Simsek, Hidayet Tunc
Raja Sengupta
Yovine, Sergio
Eskafi, Farokh
1999

We are interested in studying the fault diagnostics of platooning vehicles. It is understood that a platoon is a string of vehicles with distributed control strategies. Vehicles rely on real-time control data from other vehicles for correct execution of their control laws. A time-driven system is responsible for delivering the control data.

Safety and Capacity Analysis of Automated and Manual Highway Systems

Carbaugh, Jason
Godbole, Datta N.
Raja Sengupta
1999

This paper compares safety of automated and manual highway systems with respect to result- ing rear-end collision frequency and severity. The results show that automated driving is safer than the most alert manual drivers, at similar speeds and capacities. We also present a detailed safety-capacity tradeo study for four di erent Automated Highway System concepts that di er in their information structure and separation policy.

A Token-Ring Medium-Access-Control Protocol with Quality of Service Guarantees for Wireless Ad-hoc Networks

Attias, Roberto
Lee, Duke
Puri, Anju
Tripakis, Starvros
Raja Sengupta
Varaiya, Pravin
2001

This report describes the design and implementation of a wireless token bus protocol for local area networks. This is the second wireless token passing protocol that has been jointly designed by the PATH program and the faculty and students of the EECS department at UC Berkeley.The first wireless token bus protocol, designed by Duke Lee and Professor Pravin Varaiya, was successfully implemented to provide the wireless network required by an automated vehicle platoon. The token passing mode of wireless medium access control was chosen to provide the delivery time guarantees required by the...

Geographical Routing Using Partial Information for Wireless Ad Hoc Networks

Jain, Rahul
Puri, Anuj
Raja Sengupta
2001

In this paper, we present an algorithm for routing in wireless ad hoc networks using information about geographical location of the nodes. We assume each node knows its geographical position and the position of the node to which it wants to send a packet. Initially, the nodes only know their neighbors but over time they discover other nodes in the network. The routing table at a node S is a list ((pi, Si)) where pi is a geographical position and Si is a neighbor of node 5’. When node S receives a packet for a node D at position pos(D), it finds the pi in its routing table which is closest...

Ad-Hoc Medium Access Control Protocol Design and Analysis for Vehicle Safety Communications

Raja Sengupta
Xu, Qing
Mak, Tony
Ko, Jeff
2004

This paper studies the design of ad-hoc Medium Access Control (MAC) protocols for a vehicle or the roadside to send safety messages to other vehicles. Such a protocol is needed by Advanced Vehicle Safety Systems (AVSS) and the national Dedicated Short Range Communications (DSRC) architecture. The problem is formulated to meet the communication requirements of vehicle safety applications and the DSRC multi-channel operation model. We propose several ah-hoc protocols, all based on the principles of repetition coding. Analytical bounds of the protocols' performance are derived. Simulations...