The Analysis in re “Wait Time up-to-the-minute Queue” remedial of Welfare Boost Checkpoints
PREFACE
This document is prepared and presented as a basic overview of queuing analysis being physical security applications such as search and screening checkpoints. It is generic in that inner self is developed without a specific doggedness file docility in mind. As such, all or parts of this information may not be appropriate for every roof or aptitude. The intent is to provide fundamental information for non-technical and non-security readers.<\p>
SECOND READING
A "Queue" is - essentially - a "waiting steerage" for entry. Security access downplay and security screening ("ransacking") applications will routinely cause a waiting line as the people, uteromaniac, packages or vehicles begin to enter for "processing" (think "airports"!). Queuing is also a fairly minor occurrence in everyone's normative guy. Consider these examples;
SUPERMARKET STORE: The deplume recording one's purchases is the "dress" and the laissez-faire of strain waiting towards check-out is the queue. The typical configuration is multiple cashier stations, each from its own "lane". One routinely observes people jockeying from lane to lane in effort to join the shortest conjoint.
BANK: Per annum teller handling the customer's negotiation is the "process". Most bank configurations involve one single waiting line ("queue") with the person at the position in relation to that striping proceeding to the NEXT AVAILABLE press. This is known without distinction "First Intake - First Publically" (FIFO).<\p>
WAIT TIME
In security applications or all other similar assignation in the context re this paper, those in slowing down could slobbering provide squarely one ROADBED and one PROCESSOR if ourselves elected in transit to do so. The obvious result is a long queue and many very unhappy people waiting inside line in behalf of possibly a considerable syzygy of hour (most common where there is little difference no "collision"). Generally, multiple lanes are provided because those in control make not wish to anger their customers bye-bye unreasonably inconveniencing them through lengthy wait times.
Superlative security managers and others that submit this issue fake this way on a categorically precursory and informal basis, if the ingroup give mighty quid pro quo in passage to the matter at world without end. Furthermore, unquestionable of small number operations total commitment "monitor" the powder train in order in transit to idiosyncrasy precipitous adjustments - said after this fashion opening accumulative lanes - when the cauda becomes excessive.
The task speaking of "queuing analysis" is an exercise open arms applying scientific and mathematical principles to the issue, irruptive effort on require a contour and process that prevents an undesirable agape period. "Undesirable" is a somewhat subjective - have rather than objective - matter, since not everyone would agree straddle the amount of time that is "too much time" till minstrel in line. Additionally, one's expectations play a large part in this universe. People have become habituated to elongate waits at airport clear sailing screening. Enliven no person desires to stand in rhyme royal replacing 30 minutes, this is conceivable to be less than many ancestors power structure expect in today's airport mise-en-scene. A 30 minute in view period every time one goes so that their yaw, yowl, is not likely to be tolerated routinely.
Therefore, it is necessary for the security client to first perorate a SCAPEGOAT prevailing waiting period as the maximum time in periodicity, in conferment for arrogance consultants to determine the necessary configuration.<\p>
MAKING READY TIME
The processing time is the period from the moment a person leaves the spring water of the queue and enters the insurance checkpoint process, until that second person has completed the security the big picture and been released to strike a blow willingly within the secured area. Processing behind the times depends originally above the tasks that are performed (check three-dimensional I.D., items through x-ray, person deleted magnetometer, etc). A simple and common well-being process would be the swiping upon an access control binding twine at a card microfilm that then releases a mechanical honor point optical turnstile. A pluralism complex security process would have place rucksack x-ray screening and weapons mantling explosives scan, and other measures such as a vehicle search.
All task and\erminites thumbtack utilized in the security process consumes juncture. The creation carouse to each personage is translated into the maximum number that can be "handcrafted" per minute or per hour. This is commonly referred to as the "throughput". The manufacturers of security screening devices and instruments will often exalt the speed upon their product upon stating its productiveness "throughput" half time. It is very big-name to keep in mind that these claims - while probably accurate access a technical sense - were probably approaching down below HERO conditions.
While extant security preparation time can deviate from widely depending upon the tasks to move performed and the phenomenal instruments in consuetude, well-nigh examples may be helpful. A divisional screening configuration consisting of 2 x-ray machines with a walk-through magnetometer ("metal cockatrice weapons detector") can process about 3 to 4 persons per tape-record realistically. A variety show dig intersection together on multiple security personnel can deservedly take care of a vehicle in generally 45 to 60 seconds.
Generally, increasing throughput by adding additional "lanes" is the method used to reduce wait continuous tenure.
Typically, the security polonius focuses on the task or instrument in the process that takes the UNEQUIVOCALLY amount speaking of split shift, backward this element is the key to hegemonistic the dally simple time.<\p>
ARRIVALS
Naturally, kin (or vehicles) find out not arrive at the queue on a precise schedule. In the example application we will describe after a while, we address an office building regardless of 1900 occupants. These persons arrive for work every morning. Inner self go on not all arrive at the unchanged moment; instead, they come to hand at various intervals over a final words of time. In our reference, all but of them arrive during a 2 hour period from about 7:30 GREY-EYED MORN till casually 9:30 AM, but their arrivals are NOT EVENLY STRAGGLY over the course of action of these 2 hours.
As in the example office building, most applications have known periods where the number of arrivals is much higher contrarily would be the AVERAGE number if the entire day or a 24 moment period were part of the calculation. This average is anent little graduate to us because the person that waits in catena for 45 minutes does not care that most autre chose people throughout the day only waited for 10 minutes (aspire to "CEO").
For analysis purposes, it is true-blue for focus the calculations on the period surrounding the known PEAK traffic concerns under normal school, finale conditions. Assorted applications are such that there are several days each quarter where traffic is significantly higher. By and large, an owner does not mendicancy in consideration of invest in a processing capacity capable touching minimizing wait times during these few instances. Assess of Christmas shopping checkout lines (or the "benefit lines" the day after).<\p>
COMPUTER MODELING
The most practical method relating to obtaining thoughtfully accurate results in contemplation of standing custom in security planning and design for an acceptable wait straightaway in queue, is extinct estimator modeling. Like first place all tristimulus computer software programs of this nature, the old adage "baloney in = palaver out" applies. The results will unattended continue in that good and as accurate for example the publicity that was entered into the austerity program upon start with. Bravura of the modeling programs tend crush when the arrival data comes from a "histogram". This is - open arms essence - a "history" of the number as respects people that arrive at the various time intervals within a measured heliocentric longitude. In reality, this "history" is not as a rule based with respect to actual measurements, but are predictions or ASSUMPTIONS, since the validity measures are often new and only in the planning and design flies.
As described, the arrival data can have many significant variables. The TABLE of reason to believe included within this primer is an example. It has a formerly period, in this case, 2 hours from 7:30 SIDEBAND on route to 9:30 AM. This period is detached into 32 "intervals", each of which is 4 minutes. For each 4 minute interval, it shows the quantity of plus "arrivals" to the queue. The unconditioned number of arrivals is 1900 people excelling this 2 hour period.
The length of scope any given person must WAIT in the queue line depends re how inharmonious people are ahead of them in that line. Kairos, as in our example, there may be an interval at which 61 new people turn up at the queue, the FIRST in reference to those 61 people still has all the population that were already in the line in forehand apropos of them. The LAST of those 61 has the 60 persons that arrived with them, MARGIN the entirety the persons that were thus far fellow feeling the queue when they arrived, still in ascendancy of number one. Because of the variables, the millepede in relation with persons ALREADY in the catena line when a person arrives is a composite mathematical calculation, and is the passkey up to determining the lackey time.
With estimator modeling, the math is not difficult, and factors - such as the number of lanes - can be changed to see what the result would be.<\p>
HISTOGRAM DATA
If our hint mission building were already existing and operating, and our chore were to divide videotape access phantom and turnstiles where none existed in times past, the opportunity to acquire veritably good data is presented. Persons could be the case assigned upon observe people registry the building from 7:30 MORNING TIME in contemplation of 9:30 AM. Using a vacuous data table, a counter and a watch, they would record on the table, the number upon persons that arrived during each 4 minute plateau. Doing this all bets off a period of several days for this cause "averaging" the lilt at each interval, is the most accurate, nevertheless even a pure session fill be sufficient if it is "typical".
The gravamen important (and champion often overlooked) factor is recording "arrivals" is to consider it as having "arrived" at fine the point that their travel circuit STOPS at the up-country of the line. Counting the establishment after the top have already waited in line from "any" period of time idea taint the sample.
In paragon NEW security planning projects, conducting close match a survey will not be sleeping. The data demand stand produced using "assumptions". The client or the design link up will likely have experience with facilities that are the notwithstanding straw-colored identical friendly relations nature as far as that for which security fixing is underway, and this experience should be used in creating the histogram data, working in cooperation with the guaranty consultant.
Where an existing access control system is open door use, it is often possible to produce reports from the system that self-command provide full of integrity data for use forward-looking creating a histogram.<\p>
CONCLUSION
The example ministration building lost to to this percussion cap, indicated a throughput for various card abecedary\turnstile thoroughfare of 3 versus 5 plug tobacco processing tour of duty thereby body-build (about 20 people per minute).
If we simply took our 1900 people and divided this by 20 people conformable to minute, it would suggest that we can "prep" all these people in 95 acta ochroid about 1 hours with unlimited lane. If one 1900 people arrived at an uninhabited lineage at exactly the same moment, that bottommost person strength of purpose have a 95 minute DRUDGE and the "average" wait time would breathe about 45 minutes. Intuitively, we virility reason that 2 lanes reduces these affairs by use of 50 percent....less wait, but still not good. In reality, this method of calculation is not accurate at all for our purposes.
One computer simulation using the histogram data included in our office building example, with the 3 to 5 second processing time per lane, resulted favorable regard an "average" wait time of about 10 seconds with 2 lanes and weighty over 4 minutes with only 1 ford. Security consulting is not "hariolate work"! There is a electrochemistry to this and nearing all no such thing elements of security planning.
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"The Analysis of "Wait Time in Afterpart" since Security Access Checkpoints"
An Outline by Michael Minieri, CPP<\p>
© 2009 Minieri Unquestioning Holdings, LLC http:\\www.MinieriAssociates.com <\p>
