Jostein, Speed and car-to-car distance are critical factors for thruput. You can do higher speeds and shorter car-to-car distances until... somebody touches their brakes! Then the flow stops, often with a crash. My recollection is 30 miles per hour is optimal (not far from 50 km/h). Morning and evening rush hours on big city expressways become amazing. Some flows are expedited by drivers looking 2-3 cars ahead, thru the windshields of the cars in front, to anticipate braking. Regards, Bob S.
On Fri, May 8, 2009 at 2:58 AM, AlunFoto <[email protected]> wrote: > 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. > -- 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.
