畢業(yè)論文外文翻譯交通事故分析的可能性和局限性

1、交通事故分析的可能性和局限性 關(guān)鍵字：后果;目的;描述;限制;關(guān)注;事故分析;可能性摘要：交通事故的統(tǒng)計(jì)數(shù)字，尤其國(guó)家一級(jí)的數(shù)據(jù)對(duì)監(jiān)控和預(yù)測(cè)事故的發(fā)展，積極或消極檢測(cè)事故的發(fā)展，以及對(duì)定義安全目標(biāo)和評(píng)估工業(yè)安全特別有益。事故分析是應(yīng)用非常有限的分析，是前瞻性分析和回顧性分析，能夠?qū)π麻_(kāi)發(fā)的交通安全系統(tǒng)和特殊過(guò)程的安全措施進(jìn)行評(píng)價(jià)。目前迫切需要一個(gè)將實(shí)時(shí)事故分析與研究相結(jié)合的行為。將自動(dòng)檢測(cè)和視頻錄制相結(jié)合的研究交通事故的科研論文會(huì)比較容易接受。這種類(lèi)型的研究最終會(huì)對(duì)交通理念有個(gè)完善的認(rèn)識(shí)。1簡(jiǎn)介本文主要是基于個(gè)人的經(jīng)驗(yàn)，研究有關(guān)交通安全、安全分析以及事故分析等在研究中的作用。由這些經(jīng)驗(yàn)推導(dǎo)出的

2、哲學(xué)思考就像通過(guò)研究和統(tǒng)計(jì)得出的實(shí)踐觀點(diǎn)。而這些調(diào)查數(shù)字已經(jīng)在其他地方發(fā)表了。在缺少直接觀察的事故中，許多方法論問(wèn)題的產(chǎn)生，導(dǎo)致不能直接測(cè)試對(duì)結(jié)果持續(xù)討論。通過(guò)看事故視頻來(lái)討論是富有成效的。事實(shí)證明，用來(lái)解釋事故的大部分有關(guān)信息就是事故中缺少的記錄。深入研究還無(wú)法回憶起所有的必要的用來(lái)測(cè)試有關(guān)事故發(fā)生的假設(shè)數(shù)據(jù)，。尤其是車(chē)-車(chē)相撞發(fā)生的車(chē)禍，這是在荷蘭城市道路交叉口錄制的視頻，一輛從岔路駛來(lái)的汽車(chē)與主干路的汽車(chē)相撞，下列問(wèn)題可以問(wèn)：為什么汽車(chē)來(lái)自次干路上，突然加速后又幾乎停止，撞上了在左側(cè)主路的一輛汽車(chē)呢？為什么沒(méi)有注意到正在駛來(lái)的車(chē)？是不是因?yàn)閮绍?chē)從右邊駛來(lái)，司機(jī)因?yàn)榍懊娴慕徊鏋樗麄兲峁┝丝?/p>

3、能性而斤斤計(jì)較？難道他向左看過(guò)，但他認(rèn)為停在拐角處的綠色貨車(chē)能讓他停下來(lái)？當(dāng)然，交通狀況并不復(fù)雜。目前這個(gè)事故中沒(méi)有騎自行車(chē)或行人在擁擠路口分散他的注意。如果停著的綠色車(chē)能夠在五分鐘內(nèi)消失，這兩輛車(chē)可能就不會(huì)相撞。在事故發(fā)生的相關(guān)條件下，幾乎不可能觀察下一個(gè)交通行為，因?yàn)榻煌ㄊ鹿适遣豢深A(yù)見(jiàn)的。由于新的視頻設(shè)備和自動(dòng)檢測(cè)事故設(shè)備的不斷發(fā)展，如在收集數(shù)據(jù)方面不需要很高的成本就能變得越來(lái)越逼真。必要的增加數(shù)據(jù)類(lèi)型也能更好的解釋交通中存在的危險(xiǎn)因素。關(guān)于事故分析的可能性和限制性的問(wèn)題是不容易回答的，我們不能確切的分析交通事故。因?yàn)槭鹿史治龊w了每一個(gè)活動(dòng)中的不同背景，并根據(jù)不同的信息來(lái)源范圍來(lái)補(bǔ)充資料

4、，特別是收集事故的數(shù)據(jù)，背景資料等，我們首先要看看在交通安全領(lǐng)域的活動(dòng)周期然后再回答事故分析的可能性與限制。這些行為主要是與交通系統(tǒng)的安全管理有關(guān)，有些則是相關(guān)的研究活動(dòng)。應(yīng)該用下面的步驟來(lái)加以區(qū)分：檢測(cè)交通安全問(wèn)題；描述問(wèn)題和它的主要特征；分析其原因分析和改進(jìn)建議；選擇和執(zhí)行安全措施；評(píng)價(jià)所采取的措施。雖然這個(gè)周期可以由同一人或一群人做出來(lái)，而問(wèn)題在每個(gè)階段（政治/管理或科學(xué)）都有不同的背景。我們用事故分析來(lái)描述這一階段。做這個(gè)決定是重要的。很多關(guān)于分析結(jié)果的方法的討論由于忽視之間的區(qū)別而成為徒勞的。政治家或道路管理人員對(duì)道路的個(gè)別事故不是很留意。他們對(duì)事故的看法往往都是一視同仁，因?yàn)榭偟慕Y(jié)

5、果比整個(gè)事故中的每個(gè)人的因素重要。因此，每次事故看做一個(gè)個(gè)體，之間相互協(xié)調(diào)就會(huì)達(dá)成安全的結(jié)果。研究人員研究事故發(fā)生時(shí)一連串事件中每個(gè)人的興趣。希望從中得到關(guān)于每次事故的詳細(xì)信息并能發(fā)現(xiàn)其發(fā)生的原因和有關(guān)的條件。政治家們希望只是因?yàn)榧?xì)節(jié)決定行動(dòng)。在最高一級(jí)事故總數(shù)減少。信息的主要來(lái)源是國(guó)家數(shù)據(jù)庫(kù)及其統(tǒng)計(jì)學(xué)處理系統(tǒng)。對(duì)他來(lái)說(shuō)，統(tǒng)計(jì)意外數(shù)字及其統(tǒng)計(jì)的波動(dòng)來(lái)進(jìn)行事故分析。這適用于事故分析中的交通安全領(lǐng)域。因此，我們將首先描述了事故的這些方面。2事故的性質(zhì)和它們的統(tǒng)計(jì)特性事故基本概念是意外，不管是其發(fā)生的原因還是引起事故出現(xiàn)的過(guò)程。兩個(gè)簡(jiǎn)單的假設(shè)通常是來(lái)描述交通事故的形成過(guò)程：-事故發(fā)生的概率與以往發(fā)生

6、的事故之間是獨(dú)立；-事故發(fā)生在時(shí)間上是同性質(zhì)的如果這兩個(gè)假設(shè)成立，那么事故是泊松分布。第一個(gè)假設(shè)與大多數(shù)的批判不符。事故是罕見(jiàn)的事件，因此不會(huì)受到以前事故的影響。在某些情況下，有一個(gè)直接的因果鏈（例如，大量的車(chē)開(kāi)到一起）這一系列的事故被認(rèn)為是一個(gè)個(gè)體事故但包含許多的車(chē)。這個(gè)假設(shè)并不適用于統(tǒng)計(jì)人員傷亡。傷亡人數(shù)往往與同一事故有關(guān)，因此，獨(dú)立性假設(shè)不成立。第二個(gè)假設(shè)乍一看似乎不太容易理解。穿越空間或在不同地點(diǎn)發(fā)生的的事故同樣具有可能性。然而，假設(shè)需要很長(zhǎng)一段時(shí)間并且沒(méi)有緩繳期。其性質(zhì)是根據(jù)理論的假設(shè)。如果其短時(shí)間內(nèi)能成立，那么它也適用于長(zhǎng)時(shí)間，因?yàn)椴此煞植甲兞康目偤?，即使他們的泊松率是不同的，但?/p>

7、屬于泊松分布。對(duì)于這些時(shí)期的總和泊松率則等于為這些地方的泊松率的總和。假設(shè)與一個(gè)真正的情況相比較計(jì)數(shù)，無(wú)論是從一兩個(gè)結(jié)果還是總情況來(lái)看都有一個(gè)基本情況比較符合。例如，對(duì)比在一年中特定的一天例如下一天，下一個(gè)星期的一天發(fā)生的交通事故。如果條件是相同的（同一時(shí)間，交通情況相同，同樣的天氣條件等），那么由此產(chǎn)生的意外數(shù)字是相同的泊松過(guò)程的結(jié)果。這一假設(shè)可以通過(guò)估算進(jìn)行測(cè)試的兩個(gè)觀測(cè)值的基礎(chǔ)上（估計(jì)是兩個(gè)值的平均值）的速度參數(shù)。概率理論能夠考慮到這兩個(gè)觀察值的平均，用于計(jì)算的平等假設(shè)的可能性。這是一個(gè)相當(dāng)強(qiáng)大的統(tǒng)計(jì)過(guò)程。泊松假設(shè)是研究了很多次，來(lái)獲得證據(jù)支持。它已經(jīng)應(yīng)用于許多情況，數(shù)的差異表明在安全性

8、的差異然后確定是否發(fā)生意外。這一程序的主要目的是檢測(cè)在安全分歧。這可能是一個(gè)時(shí)間上的差異，或不同的地方或不同的條件。這種差異可以指導(dǎo)改進(jìn)的過(guò)程。由于主要關(guān)注的是，以減少意外的發(fā)生，這種分析可能導(dǎo)致對(duì)治療中最有前途的領(lǐng)域。為這樣一個(gè)測(cè)試應(yīng)用程序的必要條件是，那意外的數(shù)字進(jìn)行比較是大到足以證明存在的分歧。在許多地方情況下，一個(gè)應(yīng)用程序是不可能的。事故黑點(diǎn)分析往往阻礙了這一限制，例如，如果應(yīng)用這種測(cè)試，找出事故是否在特定的位置數(shù)是高于平均水平。該程序的描述，也可以使用，如果發(fā)生意外乃根據(jù)數(shù)的特點(diǎn)找到有前途的安全目標(biāo)。不僅聚集，而且還與分類(lèi)泊松假設(shè)成立，而意外數(shù)字可以相互測(cè)試的泊松假設(shè)的基礎(chǔ)。這種測(cè)試

9、是相當(dāng)麻煩的，因?yàn)槊總€(gè)特定的情況下，每一個(gè)不同的泊松參數(shù)，即，對(duì)所有可能結(jié)果的概率必須計(jì)算應(yīng)用測(cè)試。然后，泊松分布近似為正態(tài)分布，均值和方差等于泊松參數(shù)。一旦均值和方差的正態(tài)分布，給出了所有的測(cè)試可以改寫(xiě)了標(biāo)準(zhǔn)零均值和方差的正態(tài)分布條件。沒(méi)有任何更多的必要計(jì)算，但測(cè)試統(tǒng)計(jì)，需要利用表繪制。3. 行車(chē)安全政策事故統(tǒng)計(jì)的應(yīng)用分析那些假設(shè)的基礎(chǔ)上描述的測(cè)試程序的類(lèi)型及其優(yōu)點(diǎn)。這種應(yīng)用最好的例子是為一個(gè)國(guó)家或地區(qū)進(jìn)行超過(guò)一年的安全監(jiān)測(cè)，用事故的總體數(shù)據(jù)（最終的特定類(lèi)型，如死亡事故）與前幾年的數(shù)據(jù)相比較。根據(jù)數(shù)年的事故序列，能夠分析出它的發(fā)展趨勢(shì)，并大致預(yù)測(cè)以后幾年的事故數(shù)量。一旦建立了這樣一種趨勢(shì)，那

10、么在誤差范圍內(nèi)未來(lái)一年或幾年都可以預(yù)見(jiàn)。從一個(gè)給定趨勢(shì)的偏差也可以進(jìn)行預(yù)測(cè)新的事件。最有名的是斯米德在1949年進(jìn)行的分析。我們將討論這個(gè)事故類(lèi)型分析更詳細(xì)的內(nèi)容。1、該測(cè)試應(yīng)用推廣到高階分類(lèi)。Foldvary和Lane（1974），在衡量強(qiáng)制佩戴安全帶的效果，誰(shuí)是最早應(yīng)用于值的4路表高階相互作用的總卡方分配的。 2、測(cè)試不局限于總體影響，但卡方值就可以分解模型內(nèi)子假說(shuō)。另外，在雙向表，卡方總可以分解成零件表互動(dòng)的作用。對(duì)1的優(yōu)勢(shì)。和2。比以前的情況是，這對(duì)許多相互關(guān)聯(lián)的（子）表和相應(yīng)的智廣場(chǎng)卡方檢驗(yàn)是由大量分析，取而代之的是一個(gè)一卡方的確切劃分。 3、投入更多關(guān)注的是參數(shù)估計(jì)。例如，在卡方分

11、割使人們有可能以測(cè)試有關(guān)行參數(shù)的線(xiàn)性或二次限制或趨勢(shì)的不連續(xù)性。4、分析的單位是從數(shù)到廣義加權(quán)計(jì)數(shù)。這對(duì)于道路安全分析，那里一段時(shí)間，道路使用者的數(shù)量，地點(diǎn)或公里數(shù)的車(chē)輛往往是必要的修正有利。最后一個(gè)選項(xiàng)是沒(méi)有發(fā)現(xiàn)在許多統(tǒng)計(jì)軟件包。安徒生1977年給出了一個(gè)用于道路雙向安全分析表的例子。工資保障運(yùn)動(dòng)的一個(gè)計(jì)算機(jī)程序。這一級(jí)沒(méi)有說(shuō)明事故原因分析。它會(huì)嘗試檢測(cè)安全問(wèn)題需要特別注意。所需的基本信息包括事故數(shù)字，來(lái)形容不安全總額，暴露的數(shù)據(jù)來(lái)計(jì)算風(fēng)險(xiǎn)，并找到一個(gè)高風(fēng)險(xiǎn)的情況下或（團(tuán)體）道路使用者。 4. 事故分析研究目的交通安全的研究是有關(guān)的事故及其后果的發(fā)生。因此，人們可能會(huì)說(shuō)，研究對(duì)象是意外。然而

12、研究人員的興趣較少集中在這個(gè)最后的結(jié)果本身，而是多在進(jìn)程更多的結(jié)果（或不結(jié)果）的事故。因此，最好是把作為他的研究對(duì)象，在流量的重要事件。一個(gè)在交通意外的過(guò)程，結(jié)果是，該實(shí)際發(fā)生是由研究者未落觀測(cè)研究的主要問(wèn)題。調(diào)查一宗交通意外，他將努力重建了間接來(lái)源的事件，如涉及的道路使用者，所提供的資料或目擊者有關(guān)情況，車(chē)輛，道路和司機(jī)的特點(diǎn)。因此這不是科學(xué)獨(dú)特的，也有一個(gè)間接的研究對(duì)象的研究更多的例子。但是，第二個(gè)困難是，該研究的對(duì)象不能被誘發(fā)。有系統(tǒng)的控制實(shí)驗(yàn)手段研究只對(duì)問(wèn)題方面的可能，而不是問(wèn)題本身。間接觀察和缺乏系統(tǒng)的控制組合使調(diào)查人員很難發(fā)現(xiàn)在什么情況下造成事故的因素。雖然研究人員主要是在事故處理

13、領(lǐng)導(dǎo)有興趣，他幾乎完全信息的后果，它的產(chǎn)品，意外。此外，事故背景是復(fù)雜的。一般來(lái)說(shuō)，可分為以下幾個(gè)方面： -考慮到交通系統(tǒng)，交通量和組成國(guó)家，道路使用者，他們的速度，天氣條件下，路面情況，車(chē)輛，道路使用者和他們的相互作用的演習(xí)，意外可以或無(wú)法預(yù)防。 -由于發(fā)生事故，也對(duì)這樣的速度和車(chē)輛質(zhì)量的因素，大量的不同，碰撞角度，對(duì)道路使用者和他們的脆弱性，影響等位置的保護(hù)，傷害是嚴(yán)重或或多或少物質(zhì)損失是多還是少可觀。雖然這些方面不能獨(dú)立研究從理論的角度看，它也從由此產(chǎn)生的結(jié)果的優(yōu)勢(shì)，區(qū)分交通情況有潛在危險(xiǎn)的數(shù)字，是由有一個(gè)意外的可能性，在這種潛在的危險(xiǎn)局勢(shì)，給定一個(gè)特定事故。這個(gè)概念框架是對(duì)風(fēng)險(xiǎn)的關(guān)于個(gè)

14、別道路使用者，以及上級(jí)的決定控制器的決定制定的一般基礎(chǔ)。在風(fēng)險(xiǎn)的數(shù)學(xué)公式，我們需要一個(gè)明確的概率空間的介紹，基本事件（的情況），可能導(dǎo)致事故組成，每個(gè)類(lèi)型的事件的概率，最終收在一次事故中，最后的具體成果，損失，鑒于事故的類(lèi)型。另一種方法是看事故特征組合，然后找出關(guān)鍵因素。這種類(lèi)型的事故分析是通過(guò)分析事故的共組或子群來(lái)開(kāi)展。事故本身是一個(gè)研究的單位，但也要研究道路因素：道路位置，道路設(shè)計(jì)（如一個(gè)彎道）等。原文出處：SWOV institute for road safety research Leidschendam（會(huì)議記錄），記錄者，.POSSIBILITIES AND LIMITATION

15、S OF ACCIDENT ANALYSISKeyword：Consequences; purposes; describe; Limitations; concerned; Accident Analysis; possibilitiesAbstraet：Accident statistics, especially collected at a national level are particularly useful for the description, monitoring and prognosis of accident developments, the detection

16、 of positive and negative safety developments, the definition of safety targets and the (product) evaluation of long term and large scale safety measures. The application of accident analysis is strongly limited for problem analysis, prospective and retrospective safety analysis on newly developed t

17、raffic systems or safety measures, as well as for (process) evaluation of special short term and small scale safety measures. There is an urgent need for the analysis of accidents in real time, in combination with background behavioural research. Automatic incident detection, combined with video rec

18、ording of accidents may soon result in financially acceptable research. This type of research may eventually lead to a better understanding of the concept of risk in traffic and to well-established theories.1. Introduction.This paper is primarily based on personal experience concerning traffic safet

19、y, safety research and the role of accidents analysis in this research. These experiences resulted in rather philosophical opinions as well as more practical viewpoints on research methodology and statistical analysis. A number of these findings are published already elsewhere.From this lack of dire

20、ct observation of accidents, a number of methodological problems arise, leading to continuous discussions about the interpretation of findings that cannot be tested directly. For a fruitful discussion of these methodological problems it is very informative to look at a real accident on video. It the

21、n turns out that most of the relevant information used to explain the accident will be missing in the accident record. In-depth studies also cannot recollect all the data that is necessary in order to test hypotheses about the occurrence of the accident.For a particular car-car accident, that was re

22、corded on video at an urban intersection in the Netherlands, between a car coming from a minor road, colliding with a car on the major road, the following questions could be asked:Why did the driver of the car coming from the minor road, suddenly accelerate after coming almost to a stop and hit the

23、side of the car from the left at the main road? Why was the approaching car not noticed? Was it because the driver was preoccupied with the two cars coming from the right and the gap before them that offered him the possibility to cross? Did he look left before, but was his view possibly blocked by

24、the green van parked at the corner? Certainly the traffic situation was not complicated. At the moment of the accident there were no bicyclists or pedestrians present to distract his attention at the regularly overcrowded intersection. The parked green van disappeared within five minutes, the two ot

25、her cars that may have been important left without a trace. It is hardly possible to observe traffic behaviour under the most relevant condition of an accident occurring, because accidents are very rare events, given the large number of trips. Given the new video equipment and the recent development

26、s in automatic incident and accident detection, it becomes more and more realistic to collect such data at not too high costs. Additional to this type of data that is most essential for a good understanding of the risk increasing factors in traffic, it also important to look at normal traffic behavi

27、our as a reference base. The question about the possibilities and limitations of accident analysis is not lightly answered. We cannot speak unambiguously about accident analysis. Accident analysis covers a whole range of activities, each originating from a different background and based on different

28、 sources of information: national data banks, additional information from other sources, specially collected accident data, behavioural background data etc. To answer the question about the possibilities and limitations, we first have to look at the cycle of activities in the area of traffic safety.

29、 Some of these activities are mainly concerned with the safety management of the traffic system, some others are primarily research activities.The following steps should be distinguished:- detection of new or remaining safety problems;- description of the problem and its main characteristics;- the a

30、nalysis of the problem, its causes and suggestions for improvement;- selection and implementation of safety measures;- evaluation of measures taken.Although this cycle can be carried out by the same person or group of persons, the problem has a different (political/managerial or scientific) backgrou

31、nd at each stage. We will describe the phases in which accident analysis is used. It is important to make this distinction. Many fruitless discussions about the method of analysis result from ignoring this distinction. Politicians, or road managers are not primarily interested in individual accident

32、s. From their perspective accidents are often treated equally, because the total outcome is much more important than the whole chain of events leading to each individual accident. Therefore, each accident counts as one and they add up all together to a final safety result.Researchers are much more i

33、nterested in the chain of events leading to an individual accident. They want to get detailed information about each accident, to detect its causes and the relevant conditions. The politician wants only those details that direct his actions. At the highest level this is the decrease in the total num

34、ber of accidents. The main source of information is the national database and its statistical treatment. For him, accident analysis is looking at (subgroups of) accident numbers and their statistical fluctuations. This is the main stream of accident analysis as applied in the area of traffic safety.

35、 Therefore, we will first describe these aspects of accidents.2. The nature of accidents and their statistical characteristics.The basic notion is that accidents, whatever there cause, appear according to a chance process. Two simple assumptions are usually made to describe this process for (traffic

36、) accidents: - the probability of an accident to occur is independent from the occurrence of previousaccidents;-the occurrence of accidents is homogeneous in time.If these two assumptions hold, then accidents are Poisson distributed. The first assumption does not meet much criticism. Accidents are r

37、are events and therefore not easily influenced by previous accidents. In some cases where there is a direct causal chain (e.g. , when a number of cars run into each other) the series of accidents may be regarded as one complicated accident with many cars involved.The assumption does not apply to cas

38、ualties. Casualties are often related to the same accident and therefore the independency assumption does not hold. The second assumption seems less obvious at first sight. The occurrence of accidents through time or on different locations are not equally likely. However, the assumption need not hol

39、d over long time periods. It is a rather theoretical assumption in its nature. If it holds for short periods of time, then it also holds for long periods, because the sum of Poisson distributed variables, even if their Poisson rates are different, is also Poisson distributed. The Poisson rate for th

40、e sum of these periods is then equal to the sum of the Poisson rates for these parts.The assumption that really counts for a comparison of (composite) situations, is whether two outcomes from an aggregation of situations in time and/or space, have a comparable mix of basic situations. E.g. , the com

41、parison of the number of accidents on one particular day of the year, as compared to another day (the next day, or the same day of the next week etc.). If the conditions are assumed to be the same (same duration, same mix of traffic and situations, same weather conditions etc.) then the resulting nu

42、mbers of accidents are the outcomes of the same Poisson process. This assumption can be tested by estimating the rate parameter on the basis of the two observed values (the estimate being the average of the two values). Probability theory can be used to compute the likelihood of the equality assumpt

43、ion, given the two observations and their mean. This statistical procedure is rather powerful. The Poisson assumption is investigated many times and turns out to be supported by a vast body of empirical evidence. It has been applied in numerous situations to find out whether differences in observed

44、numbers of accidents suggest real differences in safety. The main purpose of this procedure is to detect differences in safety. This may be a difference over time, or between different places or between different conditions. Such differences may guide the process of improvement. Because the main con

45、cern is to reduce the number of accidents, such an analysis may lead to the most promising areas for treatment. A necessary condition for the application of such a test is, that the numbers of accidents to be compared are large enough to show existing differences. In many local cases an application

46、is not possible. Accident black-spot analysis is often hindered by this limitation, e.g., if such a test is applied to find out whether the number of accidents at a particular location is higher than average. The procedure described can also be used if the accidents are classified according to a num

47、ber of characteristics to find promising safety targets. Not only with aggregation, but also with disaggregation the Poisson assumption holds, and the accident numbers can be tested against each other on the basis of the Poisson assumptions. Such a test is rather cumbersome, because for each particu

48、lar case, i.e. for each different Poisson parameter, the probabilities for all possible outcomes must be computed to apply the test. In practice, this is not necessary when the numbers are large. Then the Poisson distribution can be approximated by a Normal distribution, with mean and variance equal

49、 to the Poisson parameter. Once the mean value and the variance of a Normal distribution are given, all tests can be rephrased in terms of the standard Normal distribution with zero mean and variance one. No computations are necessary any more, but test statistics can be drawn from tables.3. The use

50、 of accident statistics for traffic safety policy.The testing procedure described has its merits for those types of analysis that are based on the assumptions mentioned. The best example of such an application is the monitoring of safety for a country or region over a year, using the total number of

51、 accidents (eventually of a particular type, such as fatal accidents), in order to compare this number with the outcome of the year before. If sequences of accidents are given over several years, then trends in the developments can be detected and accident numbers predicted for following years. Once

52、 such a trend is established, then the value for the next year or years can be predicted, together with its error bounds. Deviations from a given trend can also be tested afterwards, and new actions planned. The most famous one is carried out by Smeed 1949. We will discuss this type of accident anal

53、ysis in more detail later.1. The application of the Chi-square test for interaction is generalised to higher order classifications. Foldvary and Lane (1974), in measuring the effect of compulsory wearing of seat belts, were among the first who applied the partitioning of the total Chi-square in valu

54、es for the higher order interactions of four-way tables. 2. Tests are not restricted to overall effects, but Chi-square values can be decomposed regarding sub-hypotheses within the model. Also in the two-way table, the total Chisquare can be decomposed into interaction effects of part tables. The ad

55、vantage of 1. and 2. over previous situations is, that large numbers of Chi-square tests on many interrelated (sub)tables and corresponding Chi-squares were replaced by one analysis with an exact portioning of one Chi-square.3. More attention is put to parameter estimation. E.g., the partitioning of

56、 the Chi-square made it possible to test for linear or quadratic restraints on the row-parameters or for discontinuities in trends.4. The unit of analysis is generalised from counts to weighted counts. This is especially advantageous for road safety analyses, where corrections for period of time, nu

57、mber of road users, number of locations or number of vehicle kilometres is often necessary. The last option is not found in many statistical packages. Andersen 1977 gives an example for road safety analysis in a two-way table. A computer programme WPM, developed for this type of analysis of multi-wa

58、y tables, is available at SWOV (see: De Leeuw and Oppe 1976). The accident analysis at this level is not explanatory. It tries to detect safety problems that need special attention. The basic information needed consists of accident numbers, to describe the total amount of unsafety, and exposure data

59、 to calculate risks and to find situations or (groups of) road users with a high level of risk.4. Accident analysis for research purposes.Traffic safety research is concerned with the occurrence of accidents and their consequences. Therefore, one might say that the object of research is the accident. The researchers interest however is less focused at this final outcome itself, but much more at the process that results (or does not resu