Peak-hour congestion is the balancing mechanism that makes it possible for Americans to pursue other goals they value, including working or sending their children to school at the same time as their peers, living in low-density settlements, and having a wide choice of places to live and work.
For example, a major commuting expressway might be so heavily congested each morning that traffic crawls for at least thirty minutes. But soon word would spread that this particular highway was no longer congested.
Drivers who had once used that road before and after the peak hour to avoid congestion would shift back into the peak period. Other drivers who had been using alternative routes would shift onto this more convenient expressway. Even some commuters who had been using the subway or trains would start driving on this road during peak periods. Within a short time, this triple convergence onto the expanded road during peak hours would make the road as congested as it was before its expansion.
After expansion, the road can carry more vehicles per hour than before, no matter how congested it is, so more people can travel on it during those more desirable periods. Also, the periods of maximum congestion may be shorter, and congestion on alternative routes may be lower. Those are all benefits, but that road will still experience some period of maximum congestion daily.
Triple convergence affects the practicality of other suggested remedies to traffic congestion. An example is staggered work hours. In theory, if a certain number of workers are able to commute during less crowded parts of the day, that will free up space on formerly congested roads. But once traffic moves faster on those roads during peak hours, that will attract other drivers from other routes, other times, and other modes where conditions have not changed to shift onto the improved roads.
Soon the removal of the staggered-working-hour drivers will be fully offset by convergence. The same thing will happen if more workers become telecommuters and work at home, or if public transit capacity is expanded on off-road routes that parallel a congested expressway. This is why building light rail systems or even new subways rarely reduces peak-hour traffic congestion. In Portland, where the light rail system doubled in size in the s, and in Dallas, where a new light rail system opened, congestion did not decline for long after these systems were up and running.
Only road pricing or higher gasoline taxes are exempt from the principle of triple convergence. From to , 1. That is why prospects for reducing peak-hour traffic congestion in the future are dim indeed. Shifts in economic activity also affect regional congestion. During the internet and telecommunications boom of the late s, congestion in the San Francisco Bay Area intensified immensely. Thus, severe congestion can be a sign of strong regional prosperity, just as reduced congestion can signal an economic downturn.
The most obvious reason traffic congestion has increased everywhere is population growth. In a wealthy nation, more people means more vehicles. But total vehicle mileage traveled has grown much faster than population. From to , the total population of the United States rose 24 percent, but total vehicle miles traveled grew 80 percent because of more intensive use of each vehicle.
The number of vehicles per 1, persons rose 14 percent and the number of miles driven per vehicle rose 24 percent. Even without any population gain in those two decades, miles driven would have risen 47 percent. One reason people drove their vehicles farther is that a combination of declining real gas prices corrected for inflation and more miles per gallon caused the real cost of each mile driven to fall 54 percent from to That helped raise the fraction of U.
Furthermore, American road building lagged far behind increases in vehicle travel. Urban lane-miles rose by 37 percent versus an 80 percent increase in miles traveled. As a result, the amount of daily traffic that was congested in the 75 areas analyzed in studies by the Texas Transportation Institute went from 16 percent in to 34 percent in Another factor in road congestion is accidents and incidents, which some experts believe cause half of all traffic congestion.
From to , the absolute number of accidents each year has remained amazingly constant, and the annual number of traffic deaths in the United States fell 18 percent, in spite of the great rise in vehicle miles traveled. So accidents could only have caused more congestion because roads were more crowded, and each accident may now cause longer back-ups than before.
Incidents are non-accident causes of delay, such as stalled cars, road repairs, overturned vehicles, and bad weather. We have seen how causes such as over-subscription, faulty devices, and security attacks can result in network congestion.
We have also discussed the effects of network congestion including generally poor user experience, packet loss, and timed out connections. Finally, we have discussed how to troubleshoot congestions in a network and highlighted some things that can be done to fix these issues. Network Congestion Just like in road congestion, Network Congestion occurs when a network is not able to adequately handle the traffic flowing through it.
Over-Utilized Devices Devices such as routers, switches, and firewalls have been designed to handle certain network throughput. Faulty Devices I once performed a network performance assessment for an organization. Security Attack In another organization I consulted for, a network of about 10 users had poor browsing experience even with the 4Mbps link they were getting from their ISP. From a technical perspective, the effects of a congested network include: Delay : Also known as Latency, Delay is the time it takes for a destination to receive the packet sent by the sender.
For example, the time it takes for a webpage to load is a result of how long it takes for the packets from the web server to get to the client. Another evidence of delay is the buffering you experience when watching a video, say on YouTube. Packet Loss : While packets may take a while to get to their destination delay , packet loss is an even more negative effect of network congestion. This is especially troubling for applications like Voice over IP VoIP that do not deal well with delay and packet loss , resulting in dropped calls and Call Detail Records , lag, robotic voices, and so on.
Timeouts : Network congestion can also result in timeouts in various applications. Since most connections will not stay up indefinitely waiting for packets to arrive, this can result in lost connections.
Troubleshooting Network Congestion Feeling the effects of network congestion is one thing but actually confirming that a network is congested is another. Ping One of the fastest ways to check if a network is congested is to use Ping because not only can it detect packet loss , it can also reveal delay in a network i.
LAN Performance Tests A tool like iPerf can be very useful in determining performance issues on a network, measuring statistics like bandwidth, delay, jitter , and packet loss.
Decongesting a network The fix for a Congested Nnetwork will Depend on the Cause: For oversubscribed links, you may need to purchase more bandwidth from your service provider. Some service providers also allow you to temporarily boost your bandwidth for a small fee. Learn the key benefits of vehicle maintenance software. August 4, Skip to main content. What causes traffic congestion? See also : How autonomous driving will change our highways and cities What are GPS jammers and how do you combat them?
Types of congestion There are two overall types of traffic congestion, according to the Department of Transportation : recurring and non-recurring. Environment A study by Dr. Mechanical Another factor that can cause traffic congestion is the case of a mechanical failing.
Human The all-too-common cause of traffic is humans. Just taking a quick look at some traffic fatality statistics from the National Highway Traffic Safety Administration gives a plain view at the chaos our decisions can cause on the road: There were 29 alcohol-impaired driving fatalities per day.
This number has been steadily increasing over the last few years. Read the Geotab report: Predicting traffic congestion with driving behavior The even-worse situation is when that last-minute braking scenario turns into a fender bender. Infrastructure Another category that could also arguably be human-caused is infrastructure. See also: Podcast: Smart Cities and data-driven traffic Getting control of the causes While environmental factors are outside of our control, technology provides some hope in solving the traffic challenges.
If you liked this post, let us know! Disclaimer Geotab's blog posts are intended to provide information and encourage discussion on topics of interest to the telematics community at large. Subscribe to the Geotab Blog Sign up for monthly news and tips from our award-winning fleet management blog. Republish this article for free Republish. Browse categories Compliance. Data and Analytics. I stated that mass transit is no savior.
That is because, for certain trips, the automobile still remains the best way to go if the densities are not great enough to support subways, light rail or buses. This is something bicycle advocates will never admit. Buses also can cause their own congestion without off-street bus terminals. The days of constructing new highways are over for most metropolitan areas.
That does not mean we should not be removing bottlenecks by adding lanes at strategic locations as DOT has recently done near the Brooklyn Bridge. I have provided at least 10 causes of traffic congestion and many solutions. In some instances little can be done. However, too many cars are only one cause of traffic congestion.
Disclaimer : The above is an opinion column and may not represent the thoughts or position of Sheepshead Bites. Based upon their expertise in their respective fields, our columnists are responsible for fact-checking their own work, and their submissions are edited only for length, grammar and clarity. If you would like to submit an opinion piece or become a regularly featured contributor, please e-mail nberke [at] sheepsheadbites [dot] com.
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