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Driving task analysis as a tool in traffic safety reasearch a

nd practice

Safety Science(2006)

Aim

The aim of this paper is in a first step to summarize and evaluate existing approaches and methods for driver task analysis. Subsequently, the main focus is on the presentation of a new procedure for driving task analysis and driver requirement assessment

Driving tasks and traffic safety

The match between the can drivers’ capabilities and the demands of the actual driving task determines the outcome in terms of a more or less safe driving behaviour.

Interaction model

Stress-strain approach(Lazarus)

Stressors (task demand) have to be coped with by individual resources (capability), the resulting balance creating a certain amount of strain (perceived task difficulty).

Tasks and requirements in car driving

Michon(1985) distinguishes between taxonomic and functional models.

4 types of approaches ( 任務分類 )can be distinguished:

1. Task-qua-task 2. Task as behavior requirement 3. Task as ability requirement 4. Task as behaviour description

不同的交通狀況會產生不同的 task

We therefore define a road traffic situation as the environment of the man–machine system driver–vehicle from the drivers’ perspective, following v.Benda (1977).

Situational analysis of behavioural requirements in driving tasks

A new method for driving task analysis and driver requirement assessment has been developed and applied in different contexts. (SAFE)

In longitudinal traffic the driving task

A combination of these “driving situations” (overtaking, car following, free driving etc.) with types of roads (A=motorways, L=rural roads and C=urban roads) and their characteristics (Table 1.).

Driving tasks in intersections

Left turn at a signed T-junction with minor priority for the driver, type C4.2-C4.2-K4

S1-S4

List of subtasks in segment 1

ST1.1: Recognize approaching a junction ST1.2: Recognize type of junction (T-

Junction) ST1.3: Left turn allowed? ST1.4: Recognize regulation of priority ST1.5: Signal driving direction ST1.6: Notice other traffic participants in

the approach to the junction.

Time structure of the subtasks

Analysis of the behavioural requirements of a driving task

The aim of analysing driving task demands is to combine task characteristics with behavioural requirements.

we tried to link two groups of theoretical notions: models of human information intake and -processing and models of car driving.

Behavioural requirements analysis

Errors

In our own task analytic work, we could sometimes refer to own empirical evidence from Weld research over many years that relied on an error counting method

Complexity

For the rating of task complexity a procedure is used that considers the number of requirements per subtask, its ratio of conscious/unconscious processing and requirements have to be fulfilled under time pressure and with special accuracy.

Risk

A risk estimate is calculated for each subtask using a combined rating of the probability of a collision and its severity.

Examples of applications of SAFE

1. Fig 6 的 subtask 1.62. Advanced driver assistance system

s (ADAS) 評估

如下圖所示

Conclusions

SAFE could give a theoretical and methodological framework for analysing safe driver behaviour in different contexts.

With SAFE a method has been established that allows the identification of which elements of the task lead to more or less complexity and objective risk in any driving task and also arrives at quantitative measurements of these dimensions.