The roughness of the surfaces covering roads is very significant from the point of view of traffic safety. Due to this the periodical checking and as precise measurement as possible of the roughness is a basic requirement. Several procedures have been worked out for the determination of the roughness of the surface. Among other such a procedure is presented by the work by Dr. Karman Abraham entitled"The Public Road Traffic Handbook" (Mú szaki Publishers, Budapest, 1978, pages 440-442). The most frequently used measuring procedure is the sand depth measurement, during which a previously measured amount of sand is smoothed out onto the road surface so that the spread out sand completely fills up the depressions in the road surface forming a continuous surface. By measuring several diameters of the sand patches made in this way the roughness of the surface can be determined.

The other very frequently applied roughness measurement procedure is the skidding resistance measurement, the instrument for which is the so-called"SRT"pendulum. In this procedure a rubber sheet of a determined size is fixed to the weight part of a pendulum.

Then the pendulum weight is lifted until it is horizontal and then released. The pendulum weight that has been moved out of its position of equilibrium, rotating around the axis it is suspended from, progresses towards the road surface, then on reaching the lower dead centre position it swings up. During the movement along this circular arc, near to the lower dead centre position the rubber sheet touches the road surface, then as a result of a determined period of friction it brakes the pendulum weight, then after passing the dead centre position it rises to a lesser degree. The amount of this rise is a characteristic of the roughness of the road surface, which can be read off the measuring device's scale.

The significant disadvantage of the known and generally applied measuring procedures is that they are slow and do not permit the continuous measurement of road surface roughness.

A deficiency of the known measuring procedures and the devices used to realise them is that the precision of the measurement depends to a large extent on the skill of the person carrying out the measurement and on the condition of the devices. Due to this the precision of the measurements does not always reach the required value.

Our aim with the testing instrument according to the invention was to overcome the deficiencies of the known solutions and to create a version with the help of which a measurement can be carried out that is more objective and more precise than with the known devices, and that can be carried out in a short period of time, and, if necessary, along the whole length of the road surface, even continuously.

The recognition that led to the testing instrument according to the invention was that if we use a uniquely formed signal receiving body for the measurement which with the assistance of a previously unknown bearing structure we place on the road surface, and the signal receiving body being moved on the road surface the vibrations that originate from there are transferred through a signal transmitting member to a evaluation unit, then the task can be solved. Our tests have shown that the vibrations from a suitably formed signal receiving body rolled on the road surface are proportional with the degree of roughness, in close correlation with it, so from the vibrations made while moving the signal receiving body the roughness may be determined.

In accordance with the set aim the testing instrument for determining the roughness of road surfaces-which contains a bearing structure and a measuring part-unit connected to the bearing structure so that it can move-is formed in such a way so that the measuring part unit has a signal receiving body that touches the road surface and is suitable for taking over the vibrations, and a sensing and signal transmitting member fitted between the signal receiving body and the bearing structure, the sensing and signal transmitting member, with the intervention of a data transmitting channel, is connected to a data recording unit and/or a signal processing and evaluation unit.

A further criterion of the testing instrument according to the invention may be that the signal receiving body has a basic member, a contact surface surrounding it and a main axle coaxial with the rotation axle of the contact surface fitted into the basic member, an swinging-member is connected to the bearing structure, the main axle is connected to the swinging-member, the signal receiving body is connected to the bearing structure in a way so that it may rotate with the assistance of the main axle.

In a version of the testing instrument the contact surface of the basic member is a rotationally symmetrical curved surface, e. g. cylinder surface. In another construction form the basic member is of a cycloid form.

In yet another version of the invention the bearing structure has one or more legs resting on the road surface, and the legs have roller elements fitted to them.

In a favourable construction example of the testing instrument the sensing and signal transmitting part-unit has a movement gauge, the movement gauge is supplied with a moving body and a stationary body, of the moving body and the stationary body one of them is fixed to the swinging-member of the signal receiving body and the other to the bearing structure.

In still a further different form of the invention the sensing and signal transmitting part-unit has an acoustic receiver, which is fixed to the bearing structure.

In a favourable version of the testing instrument the signal processing and evaluation unit is a computer device, practically a portable computer, while the data recording unit may be e. g. a memory chip or also a computer device, e. g. a microcomputer.

The advantage of the testing instrument according to the invention is that with a simple procedure it makes it possible to determined the roughness of a surface quickly, precisely and continuously, which was not possible with the solutions used until now.

A further advantage is that as a consequence of the structure of the testing instrument the performance and result of the measurement is essentially independent of the skill of the person carrying out the measurement, and so the precision of the measurement can be improved to a great extent, furthermore, the reproducibility of the results also increases, which further increases the reliability of the measurement.

We now present the testing instrument according to the invention in connection with a construction example, on the basis of a drawing. On the drawing Figure 1 is a side view of the testing instrument, partly in section.

On figure 1 there is a practical construction form of the testing instrument 10 according to the invention. It can be observed that the testing instrument 10 is formed by an assembly consisting of a bearing structure 20 and a measuring part-unit 30 connected to it consisting of a signal receiving body 40 and a sensing and signal transmitting part-unit 50. The bearing structure 20 has legs 21, which rest on the road surface I with the help of rolling elements 22 connected to the legs 21 so that they may rotate. The swinging-member 45 is connected to the bearing structure 20 through an axle-like connection element 23, to the end of which opposite to the connection element 23 the disc form basic member 41 that forms a part of the signal receiving body 40 is connected with the insertion of a main axle 44. The basic member 41 is delineated by the contact surface 42, which is practically a rotationally symmetrical curved surface, in this case a cylindrical shell.

On figure 1 it can be seen that the rotation axis 43 of the contact surface 42 of the basic member 41, and the main axis 44 serving to connect the swinging-member 45 and the basic member 41 are coaxial. The contact surface 42 of the basic member 41 of the signal receiving body 40-similarly to the rolling elements 22-rests on the road surface 1.

The sensing and signal transmitting part-unit 50 is inserted between the bearing structure 20 and the signal receiving body 40. In the presented construction form the sensing and signal transmitting part-unit is formed by the movement gauge 51, which in this case is an optometer of the type HEIDEHANN LS 323. The movement gauge 51 consists of a moving body 52 and a stationary body 53. In the present version the moving body 52 is fixed to the swinging-member 45 that carries the basic member 41, and the stationary body 53 is fixed to the leg 21 of the bearing structure 20. In accordance with this during the movement of the basic member 41 and the swinging-member 45 and in unison with this the positions of the moving body 52 and the stationary body 53 change with respect to each other.

The sensing and signal transmitting part-unit 50, with the help of the data transfer channel 60, is connected to the data recording unit 70 fixed to the swinging-member 45. In this version the data recording unit 70 is a microcomputer suitable for storing the measured data. Naturally in the case of selecting a suitable data transfer channel 60, the sensing and signal transmitting part-unit 50 may be connected to the signal processing and evaluation unit 80. A version, however, is also possible in which the signal processing and evaluation unit 80 is not at the scene of the measurement. In this case after completing the measurement the data stored in the data recording unit 70 may be fed into the signal processing and evaluation unit 80 at a place distant from the scene of the measurement.

The signal processing and evaluation unit is practically a computer device with the appropriate level of performance, e. g. portable computer.

On using the testing instrument according to the invention the testing instrument 10 is attached to a suitable towing device-not shown on figure 1-e. g. motor vehicle so that the rolling elements 22 positioned on the legs 21 of the bearing structure 20, and furthermore, the contact surface 42 of the basic member 41 of the signal receiving body 40 rest on the road surface 1. Following this the vehicle starts off and starts to tow the bearing structure 20, during the movement of which the rolling elements 22 and the contact surface 42 of the basic member 41 also roll on the road surface 1.

Due to the connection element 23 connected to the bearing structure 20, the swinging- member 45 and the main axle 44 of the basic member 41 in unison with this may move during the towing of the bearing structure 20 with respect to the leg 21 of the bearing structure 20. Due to the macro-roughness of the road surface 1 due to the vibrations occurring in the basic member 41 the swinging-member 45 also starts to vibrate, and the moving body 52 of the movement gauge 51 attached to the swinging-member 45 moves with respect to the stationary body 53.

As a consequence of the vibrations of the parts of the movement gauge 51 with respect to each other signals in proportion with the vibrations appear in the data transfer channel 60, which go to the data recording unit 70, and are stored there until the measurement is completed.

Following completion of the measurement the information stored in the data recording unit 70 may be read out and with the help of the data processing and evaluation unit 80 data relating to the roughness of the road surface 1 can be determined.

Naturally, as we have mentioned a solution can also be imagined in which the data processing and evaluation unit 80 is directly connected to the sensing and signal transmitting part-unit 50 through the data transfer channel 60. In this version the information sent by the sensing and signal transmitting part-unit 50 get into the data processing and evaluation unit 80 during the period of measurement, where in this way the result relating to the roughness of the road surface can be immediately determined.

It also has to be mentioned that the sensing and signal transmitting part-unit 50 does not only have to be the movement gauge 51, but it may also be another suitable measuring device, in this way among others it may be an acoustic receiver 54 which receives the sound vibrations formed during the rotation of the basic member 41 of the signal receiving body 40. After this the data transfer channel 60, the data recording unit 70 and the data processing and evaluation unit 80 determine the data characteristic of the roughness of the road surface 1 from these sound vibrations.

The testing instrument according to the invention can be used for the fast, precise and continuous determination of the roughness of road surfaces.

List of references 1 road surface 10 testing instrument 20 bearing structure 21 leg 22 rolling elements 23 connection element 30 measuring part unit 40 signal receiving body 41 basic member 42 contact surface 43 rotation axle 44 main axle 45 swinging-member 50 signal transmitting part-unit 51 movement gauge 52 moving body 53 stationary body 54 acoustic receiver 60 data transfer channel 70 data recording unit 80 data processing and evaluation unit