IIRC, there are two main parameters deciding the throughput. One is the speed limit in the constricted area, and the other is the amount of congestion cluttering the entrance to the constricted area. From the same memory, I have it that 50 km/h is the optimal throughput speed for a constricted area (some consideration of accident risk, car-to-car distance and traffic speed all together). For the congestion part, I think the argument went that if everyone drives as far as possible before merging, it requires a near full stop for everyone to merge the lanes. With early merging (and therefore gradual deceleration), traffic would flow better because everyone only have to reduce speed to what applies in the constricted area. I think there was some consideration of accident risk involved there too.
Doesn't take many cheaters to blow that theory anyway, though... Jostein 2009/5/8 Bob Sullivan <[email protected]>: > Bob W, > I think not. > You are letting geometry confuse you. > The service rate is the rate at which cars are disgorged from the queue. > 100 yards of construction may have 1, 2, 3, or 10 cars traversing it > single file. > 200 yards of construction would have twice as many cars but still the > same service rate. > 1000 yards of construction could have 10X the cars and still the same > service rate. > Regards, Bob S. > > On Thu, May 7, 2009 at 5:21 PM, Bob W <[email protected]> wrote: >> The issue of fairness is dealt with at the time of merging, whenever it's >> done, by the drivers all letting one person go first. If the merge is at the >> last possible time and everybody plays by the rules there can be no >> unfairness. >> >> Each traffic lane is equivalent to a server in a queueing system. The size >> of the queue is determined by the arrival rate, the number of servers, and >> the service time. By reducing the number of servers - that is, by reducing >> the highway to one lane, queues are more likely to build up. Similarly, by >> increasing the service time the queues are likely to increase. >> >> In this example the service time is the time it takes for a car to pass >> through the road works which might be, for example, 100 yards long. If >> everybody merges 100 yards early they take a lane out of commission before >> they need to, making the 'pipe' 200 yards long and thereby increasing the >> time it takes to get through - the service time (probably by 2X). >> >> Bob >> >>> >>> >>> Bob W, >>> Gotta do the math. >>> The service rate is fixed. The length of the queue, be it one or two >>> lanes wide depends completely on the arrival rate. Stack 'em in one >>> lane, two lanes, or three lanes it doesn't matter. Average wait time >>> will be the same. >>> The issue is fairness as some asses try to cut into the queue and get >>> thru faster. >>> For every minute they gain on the average, the rest of the group >>> suffers an additional minute wait. >>> Regards, Bob S. >>> >>> On Thu, May 7, 2009 at 4:38 PM, Bob W <[email protected]> wrote: >>> > Sure, but the earlier they merge, the longer the pipe (ie >>> longer service >>> > time), which leads to longer queues. >>> > >>> >> >>> >> Bob, >>> >> That's not really true. >>> >> Make the pipe as big as you want (as many lanes) before the >>> >> constriction (to one lane). >>> >> Traffic flow will not improve. >>> >> Regards, Bob S. >>> >> >>> >> On Thu, May 7, 2009 at 2:29 AM, Bob W <[email protected]> wrote: >>> >> > If everyone merges early they still need to know the rule >>> >> to avoid huge jams >>> >> > in one or both lanes, but the unused lane is no longer >>> >> serving traffic, so >>> >> > the total speed of the traffic is much slower. >>> >> > >>> >> > Bob >>> > >>> > >>> > -- >>> > PDML Pentax-Discuss Mail List >>> > [email protected] >>> > http://pdml.net/mailman/listinfo/pdml_pdml.net >>> > to UNSUBSCRIBE from the PDML, please visit the link >>> directly above and follow the directions. >>> > >>> >>> -- >>> PDML Pentax-Discuss Mail List >>> [email protected] >>> http://pdml.net/mailman/listinfo/pdml_pdml.net >>> to UNSUBSCRIBE from the PDML, please visit the link directly >>> above and follow the directions. >>> >> >> >> -- >> PDML Pentax-Discuss Mail List >> [email protected] >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link directly above and >> follow the directions. >> > > -- > PDML Pentax-Discuss Mail List > [email protected] > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions. > -- http://www.alunfoto.no/galleri/ http://alunfoto.blogspot.com -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
