Book excerpt: Rural two-lane highways constitute a large percentage of the highway system in Kansas. Preserving, expending, and enhancing these highways require the set-up of a large number of one-lane, two-way work zones where traffic safety has been a severe concern. Aimed at reducing the work zone crashes attributable to inattentive driving, the Kansas Department of Transportation (KDOT) initiated a research project to evaluate the effectiveness of a traffic warning sign that is assembled by using the emergency warning flashers of the vehicles in one-lane, two-way work zones. This warning sign was named as the Emergency Flasher Traffic Control Device (EFTCD). It works in the following fashion. When a vehicle entering a one-lane, two-way work zone where stopping is required for waiting to pass the work zone, the driver is required to turn on its emergency warning flashers to warn the following vehicles of the work zone stopping condition. The EFTCD is flexible and cost-effective and may particularly benefit those work zones that are frequently moved due to the construction progress. To accurately evaluate the effectiveness of the proposed EFTCD, researchers conducted experiments in three one-lane, two-way work zones in Kansas including two with a 55-mph speed limit and one with a 65-mph speed limit. During experimental period, researchers collected vehicle speed data with and without the EFTCD and surveyed drivers for their interpretation of this warning sign and recommendation on its potential implementation. Analyses results showed that the EFTCD effectively reduced the mean speeds in work zones as well as the proportions of notably high speeds. In addition, survey results indicated that the EFTCD successfully captured the attention of most drivers when they approached the work zones. A majority of drivers recommended the implementation of this warning sign in the work zones. Therefore, researchers concluded that the EFTCD was effective in one-lane, two-way work zones. Recommendations on future research were also presented based on the results of this study. The outcomes of this research project benefit not only Kansas, but also other States where rural two-lane highways constitute a high percentage of their highway systems.