When simulating the traffic operations we use one standard driver. This driver represents the 85th percentile of the driving public. The reaction time that is used in anlysis is 2.5 seconds. This is the value that is endorsed by the American Association of State Highway and Transportation Officals (AASHTO). This is the time it takes the driver to begin taking action. This is simply a statistically significant time which is representative of 90% of the population. In cases where needed, such a retirement village for example, the reaction time may be raised to better represent the population in that location. Also in the case of pedestrians a travel speed of 4.93 ft/sec is used this also may be adjusted depending on the application. This means that a traffic engineer in California, New Jersey and Florida will most likely be designing for the same driver. Some of the modeling software that I use is a program called Synchro, which helps coordinate signal groups and show the flows on all links in the system, and a program called HCS which helps time the signals in the best way possible for the entire driving public.
Yes, roundabouts are superior for providing good traffic flow. There is however often a big drawback to these. Usually the locations with the largest traffic density are also very developed. As a result the right-of-way needed for construction of traffic circles can rule out the use of them. As a result of the federal government holding back your roadway money and state governments running out of money this has become a major restriction.
I currently work as a Traffic Signal Designer in South Western Pennsylvania. I would like to clear up a few issues related to the comments being made in this post. First, in regards to the traffic detectors, the most common is a detection loop (appears as hexagonal cut in the pavement) which is an induction loop cut under the traffic stream to detect traffic. Another increasingly common detection system is a video camera which uses pattern matching to sense a vehicle sitting on the approach. This detection, particularly on the side roads, helps to provide the best efficiency of operations for the intersection by passing the most vehicles in the least time possible. Secondly, the concept refered to in this post of serving a group of approaching vehicles (a platoon) is currently employed in the US. It is however mainly used in locations where signals are closer than 1 mile apart. This is accomplished by offseting the times for the signals so the vehicles may pass through a series of signals after being stopped at one. Finaly in regards to the comment on SCOOT. There are several different systems which are used to monitor and optimize traffic signal systems. All the signals are linked together and communicate to one central location for instructions. By using the detectors at all the signals it is possible to determine the amount of traffic in the system and adjust according. Companies such as Naztec, Eagle, and Econolite all have systems to accomplish this and many large and medium size cities employ this technology.
I'm not sure if this will help or not but here at West Virginia University we have a few handicap accessable comp. labs. They use among other things a foot mouse for these students. I can do some further reasearch on this if you think it will help. Lemme know at snale@wvu.edu scott
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When simulating the traffic operations we use one standard driver. This driver represents the 85th percentile of the driving public. The reaction time that is used in anlysis is 2.5 seconds. This is the value that is endorsed by the American Association of State Highway and Transportation Officals (AASHTO). This is the time it takes the driver to begin taking action. This is simply a statistically significant time which is representative of 90% of the population. In cases where needed, such a retirement village for example, the reaction time may be raised to better represent the population in that location. Also in the case of pedestrians a travel speed of 4.93 ft/sec is used this also may be adjusted depending on the application.
This means that a traffic engineer in California, New Jersey and Florida will most likely be designing for the same driver.
Some of the modeling software that I use is a program called Synchro, which helps coordinate signal groups and show the flows on all links in the system, and a program called HCS which helps time the signals in the best way possible for the entire driving public.
Hope this was what you were looking for.
Yes, roundabouts are superior for providing good traffic flow. There is however often a big drawback to these. Usually the locations with the largest traffic density are also very developed. As a result the right-of-way needed for construction of traffic circles can rule out the use of them. As a result of the federal government holding back your roadway money and state governments running out of money this has become a major restriction.
I currently work as a Traffic Signal Designer in South Western Pennsylvania. I would like to clear up a few issues related to the comments being made in this post. First, in regards to the traffic detectors, the most common is a detection loop (appears as hexagonal cut in the pavement) which is an induction loop cut under the traffic stream to detect traffic. Another increasingly common detection system is a video camera which uses pattern matching to sense a vehicle sitting on the approach. This detection, particularly on the side roads, helps to provide the best efficiency of operations for the intersection by passing the most vehicles in the least time possible. Secondly, the concept refered to in this post of serving a group of approaching vehicles (a platoon) is currently employed in the US. It is however mainly used in locations where signals are closer than 1 mile apart. This is accomplished by offseting the times for the signals so the vehicles may pass through a series of signals after being stopped at one. Finaly in regards to the comment on SCOOT. There are several different systems which are used to monitor and optimize traffic signal systems. All the signals are linked together and communicate to one central location for instructions. By using the detectors at all the signals it is possible to determine the amount of traffic in the system and adjust according. Companies such as Naztec, Eagle, and Econolite all have systems to accomplish this and many large and medium size cities employ this technology.
I'm not sure if this will help or not but here at West Virginia University we have a few handicap accessable comp. labs. They use among other things a foot mouse for these students. I can do some further reasearch on this if you think it will help. Lemme know at snale@wvu.edu scott