Quality assurance is an important component of concrete construction. In most cases the quality of concrete is assessed using 28 day companion cylinder strengths Because corrections cannot be done economically after 28 days, the quality of concrete is always monitored at earlier stages. The most widely used quality control measure of plastic concrete is slump. The other measures are air content and wet density.

<p>Young, middle and older drivers were motored towards a traffic signal face and were required to report whether the illuminated signal lens was modulating. No significant differences were found among the three age groups in the distance at which modulation was first reported nor in the change of the modulation pattern as they approached the signal face. The modulating of the illuminated green lens was percieved signifcantly further away than was the red lens. These distances increased during trials associated with inclement weather.

The purpose of the following research was to determine
whether conspicuity of an illuminated traffic signal
lens could be increased with a modulating incandescent
light source. Experiments were conducted both in the
laboratory and a controlled field setting under normal
and degraded viewing conditions using both static and
dynamic testing situations.

The purpose of the following research was to determine whether conspicuity of an illuminated traffic signal lens could be increased with a modulating incandescent light source. Experiments were conducted both in the laboratory and a controlled field setting under normal and degraded viewing conditions using both static and dynamic testing situations.