Objective

A work zone (WZ) is visually confusing, and while no WZ looks like any other, they all share a common feature. All of them present an array of flashing light signals which are especially prominent at night. These signals ignite with no relation to one another. Each, by itself, is designed to be highly visible, attention-getting and salient, being positioned high on vehicles, along barriers and on other equipment. Our idea is that the overall visual appearance of a WZ could be made much more compatible with the needs of passers-by, if the signaling were coordinated in time. This project will study three issues: First, using standard laboratory psychophysical procedures we will test the conjecture that a coordinated signal pattern is less confusing to an observer. Next we will work with PATH personnel to study the feasibility of using wireless communication to coordinate light ignition times and to create coherence among the warning lights. Finally, we will study the feasibility of triggering the signals in sequence to create a visible pattern that is instructive to the passing driver. We call this approach: Global Visual Signal Integration (GVSI). Our hypothesis is that GVSI can lessen the cognitive demands on passing drivers enabling them to more safely and reliably negotiate the WZ.

Methodology

We plan two parallel tasks. The first will be to study simulated lane or speed keeping with and without coherence among a sea of distracting warning signals. To accomplish this aim we will utilize the pre-simulator developed during an earlier PATH project. That system allows us to present a steering task along a simulated road whereby error (departure form the center of the lane) can be appraised over time. We will reconfigure that task so that an array of randomly flashing simulated warning signal (much as one might encounter in and near a WZ) serves to distract the observer. We will then compare integrated squared error in the lane-keeping task under that condition with a related condition in which all warning signals ignite simultaneously.

The second task will be to study the feasibility of establishing a wireless link from one WZ warning signal to another so that the ignition of the first triggers that of the second. It will be appreciated that if this happens essentially simultaneously, the entire WZ will flash together. To accomplish this we will draw on the expertise of PATH device engineers who are presently studying wireless communication between the infrastructure and either vehicles or other infrastructure elements. We will fabricate a mock-up of two warning lights which use wireless communications to flash in synchrony at a rate of one Hertz.

Finally, we will generate a proposal for a subsequent study in which lights in the WZ are flashed in a sequential pattern using wireless communications and GPS sensing.