Most existing thermal comfort models are only applicable only in uniform, steady-state thermal environments. This thesis presents results from 109 human subject tests that were performed under non-uniform and transient conditions in the UC Berkeley Controlled Environmental Chamber. In these tests, local body surfaces of the subjects were independently heated or cooled while the rest of the body was exposed to a warm, neutral or cool environment. Skin temperatures, core temperature, thermal sensation and comfort responses were collected at one- to three-minute intervals. Based on these tests, we have developed predictive models of local and overall thermal sensation and comfort:

Local thermal sensation for 19 body parts

Local thermal comfort model for 19 body parts

Overall sensation model

Overall comfort model

A separate set of tests was carried out in an automobile in a climate-controlled wind tunnel at the Delphi Harrison facility in Lockport, NY. These tests simulated conditions found in vehicles during both hot and cold weather. The subjects’ body temperatures, thermal sensation and thermal comfort were measured similarly to those in the UCB chamber tests. The results of the Delphi tests were primarily used for model validation. The validation results show that the models predicted the actual sensation and comfort votes well.

The models will be useful for designing and evaluating non-uniform and transient environments in buildings, vehicles, and outdoors.

The fundamental diagram is an important element in a variety of transportation studies. While various shapes of the fundamental diagram have been proposed and numerous debates on the best-fit fundamental diagram haven been made, why the fundamental diagram has many different shapes has not been well explained. This study introduces time gap as a key parameter to understand drivers’ behavioral differences at different locations and traffic conditions, then relate it to the shape of the fundamental diagram. From I-80 freeway event detector data, it is shown that time gap follows a certain probabilistic distribution and its mean value varies along locations. When downstream congestion is expected, drivers tend to take larger time gap than otherwise. It also turns out that divers take different time gaps for different travel speeds. Three different types of time gap-speed diagrams are identified and matched to Greenberg, reversed-lambda, and inverted-V types of fundamental diagrams, respectively.

The fundamental diagram is an important element in a variety of transportation studies. While various shapes of the fundamental diagram have been proposed and numerous debates on the best-fit fundamental diagram have been made, why the fundamental diagram has many different shapes has not been well explained. This study introduces time gap as a key parameter to understand drivers' behavioral differences at different locations and traffic conditions, then relate it to the shape of the fundamental diagram. From I-80 freeway event detector data, it is shown that time gap follows a certain probabilistic distribution and its mean value varies along locations. When downstream congestion is expected, drivers tend to take larger time gap than otherwise. It also turns out that drivers take different time gaps for different travel speeds. Three different types of time gap-speed diagrams are identified and matched to Greenberg, reversed-lambda, and inverted-V types of fundamental diagrams, respectively.

We present in this paper a new car-following theory that can reproduce both the so-called capacity drop and traffic hysteresis, two prominent features of multiphase vehicular traffic flow. This is achieved through the introduction of a single variable, driver response time, that depends on both vehicle spacing and traffic phase. By specifying different functional forms of response time, one can obtain not only brand new theories but also some of the well-known old car-following theories, which is demonstrated in this paper through both theoretical analyses and numerical simulation.

We present in this report a new car-following theory that can reproduce both the so-called capacity drop and traffic hysteresis, two prominent features of multi-phase vehicular traffic flow. This is achieved through the introduction of a single variable, driver response time, that depends on both vehicle spacing and traffic motion. By specifying different functional forms of response time, one can obtain not only brand new theories but also some of the well-known old car-following theories, which is demonstrated in this report through both theoretical analyses and numerical simulation.

There have been numerous studies of the morning commute problem in a network with a single route or parallel routes with a single bottleneck on each route. Most congested networks, however, often contain more than one congestion spot along each route. In such networks, it is usually difficult to derive analytically their system-optimal traffic patterns and the tolls that realize them. In this paper, we study the morning commute problem in such a network with certain special topological features – a freeway with multiple entry/exit ramps and a surface street grid with large capacities. For this type of networks, we investigated the basic characteristics of their optimal dynamic traffic patterns and the corresponding tolling scheme, for which a graphical solution procedure was also developed. In this network, we found that at system-optimum: (1) the aggregate traffic flow on the freeway has a staircase temporal profile, and piecewise linear dynamic tolls can be imposed on a subset of ramps to achieve it; (2) among all the off-ramps in use, the ones closer to the destination are being tolled longer with higher maximum toll charges than the ones farther away from the destination; and (3) among all the on-ramps in use, the ones with larger cumulative volume-to-capacity ratios are being tolled longer with higher maximum toll charges. Some practical implications of these findings to corridor traffic management were also discussed.

Subjects were exposed to sequences of partial-body cooling and warming over a period of three hours. Skin temperatures, core temperature, thermal sensation, and comfort responses were collected for nineteen local body parts, and for the whole body. This paper relates local thermal sensations and comfort to skin and core temperatures, and examines how the thermal sensation and comfort perceived for individual body parts affect thermal sensation and comfort perceived for the whole body. Overshoot in sensation and comfort is stronger when local body parts are cooled or warmed than when the whole body experiences a step-change.