08-21-2008, 02:12 PM
Aloha,
The August 15 2008 issue of "The Week" had an article adapted from a new book, "Traffic," by Tom Vanderbilt. The whole article is on their web site (http://www.theweekdaily.com) but you have to be a subscriber to access it.
Along with a lot of other interesting research and statistics and commentary on traffic were these, re roundabouts:
"Roundabouts are our friends. Many people assume that roundabouts cause congestion. But a properly designed roundabout can reduce delays by up to 65 percent over a traditional intersection. Sure, an individual driver who has a green light may fly through an intersection much more quickly than through a roundabout. Roughly half the time, however, the light will not be green, and even if it is there is often a rolling queue of vehicles just starting into the intersection after sitting at the previous red. Drivers have to slow down as they approach a roundabout, but under typical traffic conditions they rarely have to stop.
Roundabouts are also safer. Traditional intersections are crash magnets—in the United States, nearly 50 percent of all road crashes occur at intersections. One reason is that at a four-way intersection there are a staggering 56 points that create a chance for you to run into someone. In roundabouts, there are 16."
Meanwhile in real life, once again I drove a bunch of roundabouts (from city streets to highway intersections) while in the NE of N. America earlier this summer and yes, they still work better than traffic lights.
Speaking of politics, those supporting "Big Dog" need to get him this info because traffic lights are one of his top platform items.
And re the idea of reducing speed limit to 45 mph on highway 130:
"Fast highways are not necessarily more efficient highways. Given a choice, most drivers rushing home on the freeway would rather go 80 mph than 60 mph. It gets you there sooner, right? Yes ... but as so often happens in traffic, what’s best for the individual is not always best for the system: According to repeated studies, highways handle more vehicles per hour at the slower speed than at the faster. The reason has to do with the gaps between vehicles, which grow with higher speeds. Even at a highway’s most efficient usage rate, only an estimated 5.5 percent of the road surface is actually being occupied by vehicles at any one time."
And most interesting, given the merge situation at the end of the Kea'au parkway (er, bypass), this on merging early vs. late:
"So what do the experts know about highway mergers? Not surprisingly, traffic engineers also can’t decide whether an early merge or a late merge generates better traffic flow.
The Early Merge, as engineers practice it, spreads out a highway merging zone by warning drivers several miles in advance that a lane closing is coming. This strategy seems to encourage drivers to merge sooner and thus produces fewer “traffic conflicts” and rear-end collisions than traditional, more abbreviated merges do. But Early Merge suffers from a critical flaw. One simulation showed that it actually takes vehicles longer to travel through the narrowed zone when they have advance warning, perhaps because faster-moving cars were being put behind slower-moving cars sooner than they might naturally have gotten there.
The Late Merge, a strategy first introduced only last decade, warns drivers well in advance that they are approaching a merge but directs them to “USE BOTH LANES TO MERGE POINT.” The beauty of the Late Merge system is that it removes the anxiety drivers may feel in choosing lanes, as well as their annoyance with a passing “cheating” driver. It also compresses what may normally be thousands of feet of potential merging maneuvers to a single point. As a result, it produces a 15 percent improvement in traffic flow over conventional merges—at least when traffic is heavy enough to create congestion.
The lesson is simple. If, like army ants, we each simply adhered to one rule instead of making our own choices, merging would be far less dangerous and stressful."
In other words, roundabouts really work better regardless, but when it comes to merging, there's not such an easy fix...
The August 15 2008 issue of "The Week" had an article adapted from a new book, "Traffic," by Tom Vanderbilt. The whole article is on their web site (http://www.theweekdaily.com) but you have to be a subscriber to access it.
Along with a lot of other interesting research and statistics and commentary on traffic were these, re roundabouts:
"Roundabouts are our friends. Many people assume that roundabouts cause congestion. But a properly designed roundabout can reduce delays by up to 65 percent over a traditional intersection. Sure, an individual driver who has a green light may fly through an intersection much more quickly than through a roundabout. Roughly half the time, however, the light will not be green, and even if it is there is often a rolling queue of vehicles just starting into the intersection after sitting at the previous red. Drivers have to slow down as they approach a roundabout, but under typical traffic conditions they rarely have to stop.
Roundabouts are also safer. Traditional intersections are crash magnets—in the United States, nearly 50 percent of all road crashes occur at intersections. One reason is that at a four-way intersection there are a staggering 56 points that create a chance for you to run into someone. In roundabouts, there are 16."
Meanwhile in real life, once again I drove a bunch of roundabouts (from city streets to highway intersections) while in the NE of N. America earlier this summer and yes, they still work better than traffic lights.
Speaking of politics, those supporting "Big Dog" need to get him this info because traffic lights are one of his top platform items.
And re the idea of reducing speed limit to 45 mph on highway 130:
"Fast highways are not necessarily more efficient highways. Given a choice, most drivers rushing home on the freeway would rather go 80 mph than 60 mph. It gets you there sooner, right? Yes ... but as so often happens in traffic, what’s best for the individual is not always best for the system: According to repeated studies, highways handle more vehicles per hour at the slower speed than at the faster. The reason has to do with the gaps between vehicles, which grow with higher speeds. Even at a highway’s most efficient usage rate, only an estimated 5.5 percent of the road surface is actually being occupied by vehicles at any one time."
And most interesting, given the merge situation at the end of the Kea'au parkway (er, bypass), this on merging early vs. late:
"So what do the experts know about highway mergers? Not surprisingly, traffic engineers also can’t decide whether an early merge or a late merge generates better traffic flow.
The Early Merge, as engineers practice it, spreads out a highway merging zone by warning drivers several miles in advance that a lane closing is coming. This strategy seems to encourage drivers to merge sooner and thus produces fewer “traffic conflicts” and rear-end collisions than traditional, more abbreviated merges do. But Early Merge suffers from a critical flaw. One simulation showed that it actually takes vehicles longer to travel through the narrowed zone when they have advance warning, perhaps because faster-moving cars were being put behind slower-moving cars sooner than they might naturally have gotten there.
The Late Merge, a strategy first introduced only last decade, warns drivers well in advance that they are approaching a merge but directs them to “USE BOTH LANES TO MERGE POINT.” The beauty of the Late Merge system is that it removes the anxiety drivers may feel in choosing lanes, as well as their annoyance with a passing “cheating” driver. It also compresses what may normally be thousands of feet of potential merging maneuvers to a single point. As a result, it produces a 15 percent improvement in traffic flow over conventional merges—at least when traffic is heavy enough to create congestion.
The lesson is simple. If, like army ants, we each simply adhered to one rule instead of making our own choices, merging would be far less dangerous and stressful."
In other words, roundabouts really work better regardless, but when it comes to merging, there's not such an easy fix...
]
]. I guess I'm surprised that there was even a question if the meeting is or isn't open by one of it's member. One call (no need for an email reply[V], no need for finding official contacts[V], no need to scratch the head[V], a one minute phone call) confirmed the status of the meeting under Chapter 92.