Ramp Signals are traffic signals at freeway on-ramps that control the rate of vehicles entering the highway. The signals can be set for different flow rates to optimize traffic flow and minimize congestion. When in operation, ramp signals will alternate between red and green lights, restricting the number of vehicles entering the freeway, thereby reducing congestion, bottlenecks and managing the traffic flow on the mainline.

Ramp signals are not a new freeway management technique. Various forms of ramp control were implemented during the late 1950's and through the 1960's in Chicago, Detroit and Los Angeles. By the early 1990's, ramp signal systems existed in 20 metropolitan areas within the United States, along with numerous cities around the world.

To see the ramp signal in action watch the video in the Video Library.

To see a list of on-ramps along I-95 in Miami-Dade County that will be implementing ramp signals in the near future, click here for Northbound, and here for Southbound.

Ramp Signaling is coming to South Florida in 2008.

A. Ramp signals are an important traffic management technique designed to keep traffic flowing on the freeways and help reduce crashes. With traffic congestion constantly increasing, sound management of the region’s transportation system is vital to the movement of people and goods throughout the region.

A. Generally, many cars try to merge on to the freeway all at once. Drivers on the freeway slow down to let the cars enter, and these slower speeds quickly cause backups. If cars enter the freeway in a spaced, controlled manner, they merge easier and with less disruption to mainline traffic. A short wait on the ramp allows drivers to increase their average freeway speed and shorten freeway travel times. By regulating the flow of traffic entering the freeways during peak traffic hours, the overall flow of traffic on the freeways will be smoother. This regulated flow means we can accommodate more vehicles per hour on the freeways, improve commute times, and provide a higher degree of safety.

A. Yes, all ramp signals along I-95 in Miami-Dade county area will essentially operate the same way. Because of the different ramp characteristics, there may be some slight modifications at specific ramps so that the ramp signals can be the most effective for actual traffic conditions at a particular location. All signalized ramps will have a sign at the entrance letting drivers know if the signals are turned on or not. There will be a signal at the end of the ramp as well as a stop bar on the pavement, and signs providing any special directions. Whenever you use any signalized on-ramp, remember to follow these basics steps:

• Signals at on-ramps work like all traffic lights: red means stop and green means go.
• Special instructions will always appear directly at the signal light itself and on other ramp signs. For example,
  • When in operation, signs located at or adjacent to signalized ramps will be illuminated. For example, signs which read “Ramp Signals in Operation When Flashing” will be turned on to notify motorists that ramp signaling is in effect.
  • Signs at each ramp signal will also be introduced informing motorists that one or two vehicles can proceed through each green light. These signs will read either “One Car Per Green” or “Two Cars Per Green”.

A. The purpose of ramp signals is to help regulate freeway traffic flow and merging during periods of intense use. Ramp signals on I-95 in Miami-Dade County will be "demand responsive" - that is, the signals will turn on based on traffic flow. What this means is that signals will typically operate during periods of heavy traffic, such as weekday morning and afternoon commute hours. Ramp signals also may be activated during the "off" hours in the event of an incident on the freeway or for special event traffic.

A. The red-green cycles will vary from ramp to ramp. The green light will typically be on for two seconds, and the red light may vary anywhere from two to thirteen seconds depending upon traffic flow conditions. These timings will be adjusted depending on current traffic conditions. Because the ramp signals will be "demand responsive", the operating hours and the red-green cycles will be controlled by traffic at that moment. Sensors in the pavement indicate how heavy traffic volumes are on the freeways. Lighter volumes would send a signal to the ramp signal controller to "tell" the signal to speed up the red-green cycles to let more cars on the freeway. Similarly, if the signals detect heavier traffic on the freeways, the red-green cycles would be adjusted to space out merging traffic at a safer rate.

A. Waiting times will vary depending upon how many cars are ahead of you on the ramp. In the slowest situation - a thirteen-second red and a two-second green cycle - four cars each minute would be allowed to enter on a specific lane; in the fastest situation, fifteen cars each minute could enter. For those traveling a good distance on one or more freeways, the time spent on the ramp is gained back - and more - with faster speeds on the freeway itself. Depending on the location and time of day, if someone is only traveling a short distance during the commute period, it might be just as fast (or faster) to use a surface street. Also, some signalized on-ramps will be used less frequently than others, and the wait will be shorter at those locations.

A. Over the years, every ramp signaling project in the United States has been subjected to exhaustive "before and after" tests using electronic counters, in-pavement sensors, computer studies, and even photography. Systems with ramp signals in place show that average speeds on the mainline freeways do increase, and sometimes rather substantially.

With the future implementation of ramp signals, it is estimated that there will be:

• Reduction in time spent in traffic due to the easing of recurring and non-recurring congestion
• Savings in gas due to less stop and go traffic on the mainline
• Savings due to a proven record of reduced crashes
• An increase in travel time reliability due to lower flow and congestion which will allow a more consistent commute time during ramp signal operation.

A. In terms of return on investment, no, because the accumulated savings to users yields dividends far beyond the minimal costs involved.

A. Generally speaking, with the implementation of ramp signals freeway crashes have been measurably reduced according to before and after studies. The Minnesota Department of Transportation conducted a study of freeway conditions with their ramp signals turned off. All 430 ramp signals in the Minneapolis/St. Paul metro area were turned off for six weeks in the fall of 2000, and the results show a definite safety benefit in favor of ramp signals. With the ramp signals turned off, there was a 26% increase in crashes - rear-end crashes were up by almost 15%, "run off the road" crashes increased by 60%, and sideswipe crashes were up 200%. Research shows that most freeway crashes occur during stop-and-go traffic conditions by inattentive drivers. Ramp signaling provides a smoother flow of traffic, which minimizes this problem.

A. Overall, congestion around the Miami-Dade County area will constantly grow, but the type of congestion referred to is known as "bottlenecking". Whenever traffic enters a freeway - and then shifts left from lane to lane - it creates a slowing pattern behind that entrance zone. This is true with or without signals. Ramp signals help to space the entrance of cars onto the freeway at a steady and safer rate, even though freeway lanes might already be congested.

A. No, it's not. Energy and air quality are somewhat improved by maintaining faster freeway flow. While vehicles obviously burn some gas while waiting on a signalized ramp, the average speed is increased on the freeway itself. The incidence of stop-and-go driving is reduced on the freeway, and this is what really burns up most of the gasoline. In terms of air quality, environmental experts have concluded that ramp signal programs slightly reduce the quantities of nitrous oxide, carbon monoxide, and reactive hydrocarbons - the pollutants in smog. Again, this is a trade-off: while there might not be any measurable differences on the on-ramps themselves, with decreased freeway stop-and-go driving and smoother flow, the overall air quality actually improves.

A. No. There are two ways ramp signals can adversely affect adjacent city streets. The first is backing of ramp traffic onto mainline city streets. FDOT has addressed this by installing end of queue detectors in the ramp signaling system that will send alerts when back-ups are occurring and will speed up the metering rate to avoid back-ups onto the city streets. However, if back-ups currently exist, they will not be eliminated by the signals.

It is also important to remember that there is often a bit of confusion during the first few days of all signaling projects, which does cause a bit more traffic congestion near the ramps. As commuters become accustomed to the signals and adjust their travel patterns, this temporary congestion disappears.

In cases where traffic continues to back up on the ramp, most problems can be handled by adjusting the signal timing. FDOT will closely monitor each signal as it is brought on-line and make adjustments as needed.

The second instance where ramp signals may pose adverse affect is in the diversion of traffic to city streets due to backlog and wait times entering the freeway. This issue has been studied in extensively in their cities where ramp signals were installed show that in those cases where traffic has increased on city streets, the volume has not been significant enough to impact the operation of these streets.

A. The ramp signals are considered traffic control devices and failure to obey a traffic control device are subject to the same rules of enforcement and fines. In Miami-Dade County the cost of receiving a citation for failure to obey a traffic control device will range from $85 up to $100 or more. The Florida Highway Patrol will be responsible for enforcing the ramp signals.

A. There is no charge for using the ramp signals.