Infrastructure

In research of Ergonomics of driver interface with the road environment: the contribution of psychological research, (Human Factors for highway engineers) (2001) Farida Saad argues, that the road infrastructure conveys a wealth of information that guides drivers´ activity and their interactions with others in situ (explicitly through devices such as road signs and road markings, and implicitly by means of the environmental context and road layout, for example). The design of the infrastructure and the formulation of the rules determining its use result from choices made by the designers of the road system in the broadest sense (including in particular road and traffic engineers and the legislators of the Highway Code), so one can regard the road infrastructure as an interface between road designers and drivers. This concept is also described by Hale and Stoop (1988), who position road design problems in terms of communication between road designers and road users and of compatibility between the formal rules of use underlying the design of the road and the effective rules applied by drivers when using the road.

Concepts that have emerged in the 1980s, such as ―positive guidance‖ (Allen and Lunenfeld, 1986),

―road readability‖ (Mazet, Dubois and Fleury, 1987), ―self-explaining roads‖ (Theeuwes and Godthelp, 1995b) and ―forgiving road‖ (IN-safety project), all raise the question of how the road infrastructure

could support drivers‘ activity. What these different approaches have in common is to stress the need to structure the road network by adopting homogenous and consistent design principles that take account of the different tasks to be performed by the various road users and the constraints on their execution. They seek to identify the relevant infrastructure features likely to provide a clear picture of the functionality of the road space: how to cross a complex intersection, who has the priority at a specific location; what kind of information can be expected; what kind of road events could happen, and so on.

Such an approach involves helping drivers to detect, identify and interpret current situations and, given the dynamic nature of driving and the associated temporal constraints, facilitating their anticipation of on-coming situations and the events that could occur. Given the collective nature of driving, it also involves facilitating interactions between drivers by enabling each driver to be prepared for their occurrence and ensuring that the rules to be applied for solving potential conflicts are clear and easily understandable. Lastly, and in the long-term, reducing the variability of road infrastructure design should make it easier for drivers to learn its functionality and its use.

The questions raised from this perspective have led researchers to

Propose diagnostic methods for spotting critical situations from a safety viewpoint (e.g., the Expectation Violation Analysis approach advanced by Allen and Lunenfeld (op. cit.) or the itinerary approaches and global safety approaches. These diagnostic approaches suggest that action should be taken at the level of the information to be conveyed to drivers, and indeed are an invitation to make profound changes in the road infrastructure.

Stress the need for improving the design process by bridging the communication gap between road system designers and traffic psychologists, suggesting that the former should spell out the rules of use induced by the design of the road and that the latter should formulate the results of their research in terms of the driver´s effective rules of use (Hale and Stoop, op.cit) Lastly, in terms of psychological research to focus work on the knowledge and strategies that drivers apply in controlling different driving situations and the tasks to be performed.

Many researches on road traffic safety have considered the relationship between infrastructures with road users´ behaviours. In order to quantify ―driver behaviour, researchers try to choose a variable which can describe and/or characterize driver behaviours. Drivers´ visibility is an example. Some values are suggested to be qualitative and quantified values for driver visibility such as ―failed to see‖,

―sight of distance‖, etc. From that, the main aim will be to determine the quantified value of driver´s PRT (perception-reaction time), driver´s stopping distance, or verbal rules of ―when driver´s visibility is poor, which means that the distance of sight is short (not long enough), then the driver cannot stop the vehicle before the hazard, and conflicts/accidents will happen‖. Such relationships (influences) are mainly direct relationship between infrastructure and conflicts/accidents due to driver behaviours (mostly due to driver errors when proceeding normal driving).

Some other researches pay attention to road based hazards and try to reduce the frequency of such hazards. Road based hazards can be categorised as permanent characteristics of the road surface (e.g. roughness, being an unsealed or gravel road), temporary characteristics of the road surface (e.g., potholes, surface irregularities), visual obstructions (e.g., stationary vehicles, vegetation), and characteristics of the road alignment (e.g., horizontal and vertical curves).

Other approaches take behaviour of speed reduction into consideration (Human factor). They argue that when crossing the intersections located on the main road, drivers' speed adjustment appeared to be a function of the characteristics of the intersection and of traffic conditions.

This research takes into consideration influences of infrastructure on road users´ behaviour of violating road traffic rules. From empirical research on the motorcycle-dominated traffic flow at intersections, as analysed from above, crowded and uncrowded traffic flow have direct influences on driver behaviours of violating road traffic regulations.

In the crowded traffic, there is a high risk of congestion, intersection space is limited, then the general attitudes of road users will be trying to take full advantage of every space he may have in order to ride further (reach his trip destination) despite the fact that he has to violate the traffic regulations. The infrastructure will have effect on the ―driver fear for congestions‖ (fear to get stuck).

In the field survey in two big cities in Vietnam, Hanoi and Ho Chi Minh City, there is a situation that the traffic problem in intersections is rather serious. The problem is not only traffic safety to road users but also bad effects to road traffic system capacity, especially at intersections.

General situation in intersection area and traffic operation at intersections in Vietnam urban areas is the inconsistence in managing and operating as well as positioning at intersections irrelevantly.

In Vietnam, the general situation in urban traffic is that congestion situation is very common, especially in peak hours. The reason is that our infrastructure cannot meet up with the mobility demand.

Let´s take two big cities of Hanoi and Hochiminh city as an example.

Approximately 6.500 automobiles and motorcycles share every 1 km length of road. Based on Hanoi police, recently there happens much traffic congestion everywhere inside the city, especially at peak hours. In almost road segments and intersections inside the city, the frequency of traffic flow is 200%

over the capacity. Hanoi police also provide that after removing the regulation that each person can only make registration for one motorcycle, the number of registered motorcycle has increased amazingly. Since the end of 2006 to June, 2007, there are new registered vehicles of 223.000 motorcycles and 21.000 autos, then the total registered vehicles come up to 193.000 autos and 1.930.000 motorcycles. In the current situation of 530 km of urban roads and more than 1.000 km of suburban roads. Then on average, there are 540 autos and 5.900 motorcycles in each km in Hanoi.

In Hochiminh city, there are statistics on registered vehicles as follows:

Table 15. Statistics on vehicles in Hochiminh city

Type of vehicles 2001 8/2002 Increasing rate

Truck (including container truck) 50.000 65.200 30%

Car 129.000 300.000 132%

Motorcycle 1.900.000 2.500.000 31%

Bicycle 2.000.000 2.000.000 -

Others 96.000 120.000 25%

(Source. Statistics data from policemen in 2007)

With such number of vehicles, if there are only 60% vehicles operating in the city at one moment, then the required space will be approximately of 4.010.512 m². Whereas, there are only 1.713 roads, with the total length of 1.685 km, road surface is approximately of 12.800.000 m². Besides, there are many narrow major corridors which also have inappropriate layout of intersections, where are black spots in traffic safety and bottleneck spots in traffic flow status.

In fact, the intersection layout and the current situation of traffic flow do not have the direct influence on driver general attitudes towards legislation, but they will impact in advance the congestion situation (temporary) at intersections. From that, along with experience of getting stuck (in the past), the fear for congestion is affected, then along with general attitudes towards rules will raise driver intention showing by the probability of violating traffic regulations.

Other important elements must be the driver perception skill. If the driver cannot recognize in such an appropriate time the traffic signal or rules of priority, then s/he may violate the traffic rules.

Infrastructure itself may also have the influence on this personality. For example, the driver rides in the minor road, with a narrow approaching angle, limited visibility, etc.

Before having the data on relationship between infrastructure and drivers´ specific-scenario acceptance of rules, there is a possibility to apply the methodology of expert system to evaluate the reasonable and appropriate level of infrastructure at a specific intersection and its measurements of traffic operation. Each intersection may be ranked as high relevant, medium and low relevant.