Ramp meters react to actual travel conditions by delaying the onset of congestion. By allowing vehicles to enter the freeway one at a time, this precludes large numbers of vehicles from joining traffic all at once. This would create slowdowns around the entrance ramp and increase travel times.

Tungsten incandescent lightbulb

The ramp metering policy provides a balance between maximizing the efficiency of the freeway system with traffic flow on the local streets while keeping ramp waits to less than four minutes. If there are too many vehicles on the ramp, this causes back ups onto local streets. The Regional Transportation Management Center (RTMC) then changes the timing on the meter so that more vehicles can flow onto the mainline.

Tungstenbulb photography

We decided not to meter at certain locations. These ramps either carry too little traffic to justify activating the meter or else they have too much traffic to effectively meter without exceeding the maximum queue waits.

Incandescent bulbs are the original form of electric lighting and have been in use for over 100 years. While Thomas Edison is widely considered to be the inventor of the incandescent bulb, there are a number of people who invented components and prototypes of the light bulb well before Edison did.

Tungstenbulb vs LED

Many incandescent bulbs are scheduled to be phased out of production by 2014. Click here to learn more about the Energy Independence and Security Act of 2007 and how it might affect you.

The incandescent light bulb or lamp is a source of electric light that works by incandescence, which is the emission of light caused by heating the filament. They are made in an extremely wide range of sizes, wattages, and voltages.

Incandescent light

Incandescent light bulbs usually contain a stem or glass mount attached to the bulb's base which allows the electrical contacts to run through the envelope without gas/air leaks. Small wires embedded in the stem support the filament and/or its lead wires.

Tungsten lightbulb vsincandescent

The enclosing glass enclosure contains either a vacuum or an inert gas to preserve and protect the filament from evaporating.

Incandescent bulbs require no external regulating equipment, have a very low manufacturing cost, and work well on either alternating current or direct current. They are also compatible with control devices such as dimmers, timers, and photo sensors, and can be used both indoors and outdoors. As a result, the incandescent lamp is widely used both in household and commercial lighting, for portable lighting such as table lamps, car headlamps, and flashlights, and for decorative and advertising lighting.

An incandescent bulb typically consists of a glass enclosure containing a tungsten filament. An electric current passes through the filament, heating it to a temperature that produces light.

One of those people was British physicist Joseph Wilson Swan, who actually received the first patent for a complete incandescent light bulb with a carbon filament in 1879. Swan’s house was the first in the world to be lit by a light bulb. Edison and Swan merged their companies and together they were the first to design a bulb that was commercially viable.