CROSS-REFERENCE TO RELATED APPLICATION This application claims priority to South African provisional patent application number 2013/07494, which is incorporated by reference herein.

FIELD OF THE INVENTION This invention relates to a system and method for vehicle overload management and, more particularly, it relates to a system and method for vehicle overload management for use along an entire road transport corridor that includes several load control stations. BACKGROUND TO THE INVENTION

Overloading of vehicles, particularly transportation vehicles, is a major problem across the globe. Overloading not only causes considerable damage to road networks and road surfaces, but also contributes to the problem of improving and maintaining road safety for all road users. Furthermore, heavy vehicle operators that adhere to loading standards are placed at a disadvantage as they cannot compete fairly with unscrupulous operators that deliberately overload their vehicles. Vehicle overload management is typically performed on road transportation corridors through the weighing of heavy vehicles at overload control stations, generally referred to as weigh bridges. These weigh bridges typically include weigh-in-motion (WIM) scales configured to quickly determine, while the vehicle is moving, whether the vehicle's weight is within allowable loading limits, and static scales configured to more accurately determine the load on each axle of the vehicle, as well as the combined weight of the vehicle, while the vehicle is stationary. Due to WIM scales determining a vehicle's weight while the vehicle is in motion, the weight measurements are generally too inaccurate to be used for prosecution purposes, thus in the event of the WIM scale indicating that a vehicle may be overloaded, the vehicle's weight will have to be more accurately determined by means of a static scale. A heavy vehicle is therefore generally, as a first step, directed through a WIM scale and if the vehicle's load is considered to be close to or over the permissible loading limit, the vehicle is directed towards a static scale so as to be weighed more accurately. Where it is found that the vehicle has been overloaded, the vehicle owner is sanctioned and often required to unload a portion of the load, or otherwise reduce the load, prior to the vehicle being permitted to continue along the corridor.

Various forms of overload monitoring systems have been developed to effectively streamline and increase the efficiency of the monitoring process described above, however, these systems typically exhibit various deficiencies.

It is common practice for good transport operators to load their vehicles at or near the allowable load limit. As a result, the inherent inaccuracies associated with most WIM scale measurements mean that vehicles loaded at or close to the permissible limits tend to be identified as overloaded, and are thus directed toward static scales for more accurate measurements. This renders WIM scale readings largely ineffective, while at the same time being time consuming to the vehicle operator as well as labour and cost intensive to control stations.

This problem is exacerbated by the fact that, if a vehicle has been loaded at or near the allowable load limit, the vehicle can be reasonably expected to be identified as being potentially overloaded by WIM scales at all or most of the control stations along a corridor. The vehicle will therefore generally have to be weighed by means of a static scale at every control station along the corridor. A further deficiency often exhibited by existing monitoring systems is that vehicles are not reliably identified at WIM scales, which in turn leads to many unnecessary or incorrect static weighing actions being performed, resulting in wasted costs and loss of time to both vehicle operators and control stations. Furthermore, the unreliable identification of vehicles at control stations results in the loss of statistical data which could otherwise be used to accurately determine when a vehicle's load determined by a WIM scale is above the permissible limit or not.

SUMMARY OF THE INVENTION

In accordance with this invention there is provided a vehicle overload monitoring system, comprising:

a plurality of control stations situated along a road transportation corridor;

each control station having a unique identifier associated therewith and including at least one vehicle weighing mechanism, at least one electronic identification mechanism configured to uniquely identify a vehicle passing through the control station, and a communications module;

wherein each control station is configured to receive, by way of the communications module, weight measurement data and vehicle identifiers gathered by one or more other control stations along the road transportation corridor, associate the received vehicle identifiers and the weight measurement data with the unique identifiers of the control stations by which they were gathered, and to at least partially utilize the associated information to determine whether the vehicle should be weighed by way of the vehicle weighing mechanism. Further features provide for the system to further comprise a remotely accessible server in data communication with a system database; and for the remotely accessible server to be configured to receive weight measurement data and a vehicle identifier from a control station, to associate the vehicle identifier and the weight measurement data with the unique identifier of the control station, and to store the associated information on the system database for use by other control stations along the road transportation corridor.

Further features provide for the server to be further configured to receive location data of a vehicle traveling along the road transportation corridor; for the location data to be transmitted to the server by way of a location detection system associated with the vehicle; for the server to be configured to determine, in real-time, a likelihood of whether the vehicle stopped and/or deviated from the road transportation corridor, so as to determine a likelihood of the vehicle's weight having changed along the corridor and/or in between one or more control stations based on the location data; and, if a high likelihood that the vehicle weight has changed is determined, flag the vehicle identifier stored on the system database to that effect.

Still further features provide for the server to be configured to receive loading area access data of a vehicle; for the loading area access data to be transmitted to the server by way of electronic sealing devices and/or electronic door sensors secured to the loading area of the vehicle; for the electronic sealing devices to be enabled to detect opening, closing and/or tampering events of the loading area of the vehicle; and for the server to be configured to determine the likelihood of the vehicle weight having changed along the corridor and/or in between one or more control stations based on the loading area access data.

A further feature provides for the location detection system to be one or more of a Global Positioning System (GPS), a Local Positioning System (LPS), a Wireless Positioning System (WPS) and the like. Yet further features provide for the electronic identification mechanism to include any one or more of a radio-frequency identification (RFID) reader, a quick response (QR) code reader, a barcode reader, and the like; and for each vehicle to have any one of an RFID tag, a QR code, a barcode or the like secured to the vehicle which uniquely identifies the vehicle. Alternatively or in addition, the electronic identification mechanism may include an automated number plate recognition (ANPR) system configured to automatically identify a vehicle from its number plate. Further features provide for the weighing mechanism of each control station to include one or more of a weigh-in-motion (WIM) scale or a static scale; and for each control station to preferably include a WIM scale and a static scale. In a preferred embodiment, each control station includes a secondary electronic identification mechanism configured to identify vehicles that are not weighed at the control station; and the remotely accessible server is configured to receive vehicle identifiers from the secondary electronic identification mechanism, to store the vehicle identifiers in the system database and to flag the vehicle identifiers received from the secondary electronic identification mechanism to indicate that the identified vehicle was not weighed. Alternatively, if the vehicle cannot be identified by way of the secondary electronic identification mechanism, for the server to be configured to notify control stations further along the road transportation corridor that an unidentified vehicle is traveling towards it.

A still further feature provides for the server to be configured to pro-actively transmit the associated information to one or more subsequent control stations located further along the road transportation corridor than the control station from which the information was received, in preparation for an identified vehicle's arrival at the subsequent control stations, the associated information being useful by the subsequent control stations to determine if an identified vehicle indicated by the WIM scale at the subsequent control station as being within predefined weight limits, should again be weighed on the static scale of the subsequent control station. The invention extends to a method for monitoring the load of a vehicle along a road transportation corridor, the method including the steps of, at a control station situated along the road transportation corridor:

receiving a vehicle identifier and weight measurement data of a vehicle being weighed with a WIM scale of the control station;

receiving weight measurement data and vehicle identifiers gathered by one or more other control stations (106) situated along the road transportation corridor and associating the vehicle identifiers and the weight measurement data with the unique identifiers of the control stations by which they were gathered; and

determining whether the vehicle should be weighed again by way of a static scale at the control station, based at least partially on the received weight measurement data gathered by the other control stations along the corridor. Further features provide for the step of determining whether the vehicle should be weighed again by way of the static scale at the control station includes the steps of:

determining whether the vehicle has previously been inspected at one or more other control stations along the road transportation corridor within a pre-determined time frame, this time frame being calculated based on normally expected travel time from the respective previous control station to the current control station, and whether the vehicle identifier has been flagged by the server to indicate a likelihood that the vehicle's weight has changed since its last inspection;

if the vehicle has not been inspected at a static scale within the predetermined time frame or the vehicle identifier has been flagged, determining whether the WIM scale weight measurement data deceeds a first pre- determined parameter and, if it does, permitting the vehicle to continue travelling along the road transportation corridor, alternatively, if the WIM scale weight measurement data exceeds the first pre-determined parameter, transmitting a notification to the control station that the vehicle is potentially overloaded and should be weighed again at the associated static scale; and if the vehicle has been inspected at a static scale within the predetermined time frame and the vehicle identifier has not been flagged, determining whether the WIM scale weight measurement data deceeds a second pre-determined parameter, set at a level higher than the first pre- determined parameter, and, if it does, permitting the vehicle to continue travelling along the road transportation corridor, alternatively, if the weight measurement data exceeds the second pre-determined parameter, comparing the weight measurement data with the previously received weight measurement data to determine whether the vehicle is potentially overloaded and should be weighed again.

Still further features provide for the method for monitoring the load of a vehicle to be performed at a remotely accessible server and wherein associated information is stored on a system database.

The invention also provides a method of calibrating a vehicle weighing mechanism at a control station situated along a road transportation corridor, the method including the steps of:

identifying a vehicle entering the control station;

weighing the vehicle utilizing the vehicle weighing mechanism to obtain a current weight measurement;

gathering previous weight measurements relating to the vehicle, the previous weight measurements having been recorded by one or more other weighing mechanism associated with one or more other control stations situated along the road transportation corridor; comparing the current weight measurement to the previous weight measurements to determine a level of variation between the measurements; and

adjusting the calibration of the vehicle weighing mechanism in accordance with the level of variation.

Further features provide for the current weight measurement and the previous weight measurements to each include weight measurements obtained utilizing a weigh-in-motion (WIM) scale and a static scale; for each WIM measurement and static scale measurement to comprise a data set; to compute the difference between the WIM scale measurement and the static scale measurement for each data set; to compute an average of the differences computed; and for the WIM scale to be calibrate in accordance with the average obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only with reference to the accompanying representations in which:

Figure 1 illustrates a vehicle overload monitoring system in accordance with the invention;

Figure 2 illustrates one embodiment of a control station form part of the system illustrated in Figure 1 ;

Figure 3 illustrates a flow diagram of a method for monitoring the load of a vehicle along a road transportation corridor making use of the system of Figure 1 ; and Figure 4 illustrates a method for calibrating a vehicle weighing mechanism at a control station along a road transportation corridor employing the system of Figure 1 . DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS

Figure 1 illustrates one embodiment of a vehicle overload monitoring system (100) in accordance with the invention. The system (100) comprises a remotely accessible server (102) in data communication with a system database (104) and a plurality of control stations (106) stationed along a road transportation corridor. Each control station has a unique identifier within the system (100) and includes vehicle weighing mechanisms (108) and at least one electronic identification mechanism (1 10). The electronic identification mechanisms (1 10) are capable of uniquely identifying a vehicle (1 12) passing through the control station (106). In a preferred embodiment and as illustrated in Figure 1 , the weighing mechanisms (108) of each control station include a weigh-in-motion (WIM) scale (1 14) and a static scale (1 16).

Furthermore, in a preferred embodiment, the electronic identification mechanism (1 10) of each control station (106) includes any one of a radio- frequency identification (RFID) reader, a quick response (QR) code reader, a barcode reader or the like, and each vehicle (1 12) passing through the control station (1 10) has any one of a RFID tag, a QR code, a barcode or the like secured to the vehicle (1 12). The electronic identification mechanisms (1 10) are capable of uniquely identifying each vehicle (1 12) passing through the control station (1 10) so as to ensure that the weight measurement data of each vehicle (1 12) may be accurately associated with the correct vehicle (1 12) identified. Preferably, low cost passive RFID tags will be secured to each vehicle (1 12), as these will ensure accurate identification of a vehicle (1 12) while at the same time keeping costs to a minimum. In an alternative embodiment, the electronic identification mechanism (1 10) may include an automated number plate recognition ("AN PR") system that is capable of accurately identifying a vehicle (1 12) based on the vehicle's number plate.

A preferred embodiment of the system (100) may further include location detection mechanisms (not shown) installed on each vehicle (1 12), which are in data communication with the server (102). The location detection mechanisms may include any one of a Global Positioning System (GPS), a Local Positioning System (LPS), a Wireless Positioning System (WPS) or the like and enable the server (102) to determine, in real-time, the location of each vehicle (1 12) at any given time. The server (1 02) is therefore enabled to track and determine, in real-time, whether a vehicle (1 12) travelling along the corridor has stopped and/or deviated from the corridor at any point during its travel.

In addition, in a preferred embodiment, the system (100) further provides for electronic sealing devices (not shown) and/or electronic door sensors (not shown) to be secured to the cargo areas (1 18) of vehicles (1 12) traveling on the corridor. It will be appreciated that such sealing devices and/or door sensors will generally only be used for vehicles (1 12) where the construction of the vehicle (1 12) allows for the cargo area (1 18) to be locked and/or sealed and such devices to be secured thereto. The sealing devices and/or door sensors are in data communication with the server (102) and are capable of transmitting loading area access data to the server (102) so as to enable the server (102) to detect tampering with the vehicle's (1 12) cargo area (1 18). Alternatively, the door sensors may be configured to record opening, closing and tampering activities on a local memory module, preferably together with accurate date- and timestamp information. The memory module may then be interrogated by a wireless communication device installed in the proximity of a control station (106) as the vehicle (1 12) passes through the control station (106), and the recorded data may be inspected by the control station (106) to determine if the cargo was accessed or tampered with along the corridor.

In use, the server (102) is configured to receive from a control station (106) the weight measurement data and vehicle identifier for each vehicle (1 12) passing through the control station (106), and to associate the weight measurement data with the correct vehicle identifier as well as the control station's identifier and store the data on the system database (104). In a preferred embodiment, during travel of a weighed and identified vehicle (1 12) along the corridor, the server (102) is capable of tracking the vehicle's (1 12) movement by means of the location detection mechanism of the vehicle (1 12) and to detect any potential tampering with the vehicle's cargo area (1 18) by means of the sealing devices and/or door sensors secured to the cargo area (1 18) of the vehicle (1 12).

If it is detected that the vehicle (1 12) had made an unexpected stop, or deviated from the expected corridor, or the sealing devices or door sensors indicate that the cargo area (1 18) of the vehicle (1 12) was accessed or tampered with, the server (102) is configured to determine the likelihood of the vehicle's (1 12) weight having changed from its last weighing at a control station (106). Where there is a likelihood that the vehicle's (1 12) weight has changed during its travel on the corridor, the server (102) is configured to mark or flag the identifier of the vehicle (1 12) stored on the system database (104) to that effect.

It will be appreciated that communication between the server (102) and the control stations (106) as well as location detection systems and electronic sealing devices and/or door sensors will all take place wirelessly over a mobile communications network (120) such as the Global System for Mobile Communications (GSM), Universal Mobile Telecommunications System (UMTS), satellite communication or the like. Alternatively, the server (102) and control stations (106) may communicate by means of a wired connection, such as telephone networks, fibre optic communication networks or the like.

Figure 2 illustrates the vehicle overload monitoring system (100) described with reference to Figure 1 , in use at one of the control stations (200) situated along the corridor. The control station (200) includes a WIM scale (202) and a static scale (204) as well as electronic vehicle identification mechanisms (206) at or near each scale (202, 204). In a preferred embodiment2, the control station (200) includes at least a first and a second boom gate (208, 210) in order to direct vehicles (212) into and through the control station (200).

In use, a vehicle (212) travelling along the road transportation corridor is, at a first stage, directed toward the WIM scale (202) where the vehicle (212) is identified by means of the electronic vehicle identification mechanism (206) and then weighed while passing over the WIM scale (202). The direction of travel of a vehicle along the corridor is indicated by arrows (213). If the vehicle's (212) weight is determined by the WIM scale (202) to be below a pre-determined minimum loading limit, the first boom gate (208) is opened, thereby permitting the vehicle (212) to return onto the road (214) and continue travelling along the corridor. However, where the vehicle's (212) weight is determined by the WIM scale (202) to be above the pre-determined minimum loading limit, the second boom gate (210) is opened, directing the vehicle (212) toward the static scale (204). At the static scale (204), the vehicle (212) is optionally again identified by means of an electronic identification mechanism (206) and then weighed. It will be appreciated that the weight measurements obtained at the static scale (204) are significantly more accurate than the weight measurements of the WIM scale (202). Once the vehicle (212) has been accurately weighed at the static scale (204), it will either be permitted to return to the road (214) and continue travelling on the corridor or the vehicle's (212) cargo may have to be adjusted so as to ensure that the vehicle's (212) weight falls within the permitted loading limits. It will be appreciated that instead of using boom gates (208, 210) to direct vehicles (212) within the control station (200), signage, preferably electronic signage, may be used. It should be noted that the procedure described in the previous paragraph is the procedure that will be followed at the first control station (200) encountered by a vehicle (212) along a corridor. Where the vehicle (212) has been weighed at a static scale (204) at a previous control station (200) within a pre-determined time frame, and the vehicle identifier has not been flagged by the server, then the vehicle (212) may not be required to proceed to the static scale (204) even where the WIM scale (202) indicates that the vehicle (212) may be overloaded. The determination as to whether a vehicle (212) needs to be weighed at a static scale (204) once the WIM scale (202) indicates that the vehicle (212) may be overloaded will be described in more detail below.

In addition, it will be appreciated that additional factors such as the vehicle type, the loading and type of loading on the vehicle, and the like, may also be taken into account when determining whether the vehicle is permitted to return onto the road or whether the vehicle should be weighed by means of the static scale.

In a preferred embodiment and as illustrated in Figure 2, each control station (200) includes a secondary electronic identification mechanism (216) in order to enable the identification of vehicles (212) that are not weighed at the control station (200). The secondary electronic identification mechanism (216) may also be used to identify vehicles (212) that were classified and/or directed to being weighed at a static scale (204), but were not so weighed. This would particularly be relevant where vehicles (212) are directed within a control station (200) through signage, and not by boom gates. The secondary electronic identification mechanisms (216) are typically located along the road (214) and are capable of transmitting vehicle identifiers to the server for storage by the server on the system database and for flagging the vehicle identifier to indicate that the vehicle (212) has not been weighed. Where a vehicle identifier has been flagged as not having been weighed, a control station (200) further along the corridor may be notified of such vehicle (212) and will be able to alert and/or sanction the vehicle (212) for passing the control station (200), alternatively, the vehicle (212) owner will simply be sanctioned for not having obeyed the rules and/or regulations. It will be appreciated that where the vehicle (212) passing the control station (200) cannot be identified, because the vehicle (212) does not have an RFID tag or the like secured thereto, the server will be enabled to notify a control station (200) along the corridor that an unidentified vehicle (212) is traveling on the corridor and the control station (200) will be able to halt and/or alert the vehicle (212). The secondary electronic identification mechanism (216) may also be equipped with an automated number plate recognition (ANPR) system so as to enable the server to record the number plate of the vehicle (212) which passed the control station (200) without being weighed.

Due to the weight measurement data and vehicle identifiers of each vehicle (212) passing through the control station (200) being stored on the system database, the data can be effectively used by other control stations (200) located further along the corridor as will be described below. It will immediately be apparent that a substantial advantage of the system is that, once a vehicle's weight has been accurately measured on a static scale (204) of one of the control stations (200) and found to be within the legal limits and recorded as such in the system database, WIM scale measurements at subsequent control stations that are close to the predetermined minimum load limit, be it slightly over or slightly under, may still allow the vehicle in question to pass through the control station (200) without having to be weighed on the static scale again. This may substantially reduce the number of weighs a given vehicle (212) may have to undergo along the corridor, in turn leading to a substantial cost and time saving to both the vehicle operator and control station. Figure 3 illustrates a flow diagram of a method for monitoring the load of a vehicle along a road transportation corridor making use of the system illustrated in Figures 1 and 2. At a first stage (300), the remotely accessible server (102) receives a vehicle identifier and weight measurement data from a control station (106) located along a road transportation corridor. The weight measurements may have been taken by a WIM or static scale at the control station and flagged as such. Where the vehicle (1 12) has not previously been weighed and identified at a control station (106), then at a next stage (302), the server (102) associates the weight measurement data with the vehicle identifier and control station identifier and stores the associated data on the system database (104). Alternatively, if the vehicle (1 12) has been previously weighed at a control station (106) along the corridor, then at a next stage (304), the server (102) identifies the vehicle (1 12) and retrieves information associated with the vehicle identifier from the system database (104). This information is then forwarded to the control station through which the vehicle (1 12) is in the process of passing. The information associated with the vehicle identifier will include weight measurement data previously received as well as the identifier of the control station (106) from which such weight measurement data was received. While still at this control station, at a next stage (306), the server (102) determines whether the vehicle (1 12) had been weighed at a previous control station (106) within a pre-determined time frame or whether the vehicle identifier had been flagged, thereby indicating that there is a likelihood of the vehicle's (1 12) weight having changed since the last weighing of the vehicle (1 12). As described above, a vehicle identifier will typically be flagged where the vehicle (1 12) exhibited some characteristic or behaviour, such as halting for a specified period of time or deviating from the corridor or the electronic sealing devices and/or door sensors indicating that tampering with the cargo area (1 18) of the vehicle (1 12) may have occurred, thereby indicating that the vehicle's (1 12) weight may have changed during travel along the corridor. Where the vehicle (1 12) has not been weighed within the pre-determined time frame or where the vehicle identifier has been flagged, then at a next stage (308), the control station (106), being in communication with the server (102), determines whether the weight measurement data falls within predetermined allowable parameters or limits, for example below the maximum loading limit. This first weighing of the vehicle (1 12) is typically done by means of a WIM scale (1 14). Where the weight measurement data falls within the pre-determined allowable parameters, then at a next stage (310), the vehicle (1 12) is permitted to continue travelling on the corridor. Where on the other hand the weight measurement data does not fall within the pre-determined allowable parameters, then at a next stage (312), the control station (106), at which the vehicle (1 12) is being weighed, determines that the vehicle (1 12) is potentially overloaded. The vehicle (1 12) will then be directed toward the static scale (1 16) so as accurately determine the vehicle's (1 12) weight.

At stage (306), where the vehicle (1 12) has been weighed within the predetermined time frame and the vehicle identifier has not otherwise been flagged, then at a next stage (314), the control station (106), being in communication with the server (102), determines whether the weight measurement from the current WIM scale falls within the pre-determined parameters.

Where the weight measurement data falls within the pre-determined parameter, then at a next stage (316), the vehicle (1 12) is permitted to continue travelling on the corridor. Alternatively, where the weight measurement data does not fall within the pre-determined parameters, then at a next stage (31 8), the control station (106), being in communication with the server (102), compares the weight measurement data received from the WIM scale with the allowed weight limits as well as with the weight measurement data associated with the vehicle identifier as captured at one or more previous control stations (106) and stored on the system database (104). Where the comparison indicates that the WIM scale measurement is over the pre-determined limits, then at a next stage (320) it is determined by the control station (106) that the vehicle (1 12) is potentially overloaded. The vehicle (1 12) will then again be directed toward the static scale (1 16) for a more accurate weighing. If the comparison also indicates that the same vehicle (1 12) was found to be over the limit at a previous control station (106) on the corridor, and that it is still over the limit, the vehicle (1 12) will be directed to the static scale (1 16) and, in addition, a notification will be transmitted to the server (102) that the prescribed control procedures at the previous control station (106) were possibly not properly applied.

Where on the other hand the comparison indicates that a variation in the weight of the vehicle from previous weight measurement data received by the server (102) and, more specifically, the weight measurement data from a previous weighing by means of a static scale (1 16), is within allowable limits, and where the vehicle identifier has not been flagged, then at a next stage (322), the vehicle (1 12) will be permitted to continue travelling along the corridor.

It will be appreciated that by interconnecting control stations along a corridor and enabling them to share the vehicle identifiers and weight measurement data, the system (100) is enabled to compare the various weight measurements as described above. The comparison of the weight measurements will in particular enable the system (100) to more accurately determine whether a vehicle (1 12) that has been loaded close to the maximum permitted load, in fact needs to be weighed by means of the static scale (1 16) again, where the WIM scale (1 14) indicates that the vehicle (1 12) is close to its maximum permissible load. This system will therefore decrease the number of static scale (1 16) weighs a vehicle (1 12) will have to undergo where the vehicle (1 12) has been loaded close to the maximum permissible load, thereby significantly decreasing the wasted time and cost involved with unnecessary static scale (1 16) weighing.

It will further be appreciated that the use of the location detection systems and electronic sealing devices and/or door sensors will enable the system (100) to effectively monitor a vehicle's (1 12) behaviour while travelling along the corridor, thereby enabling the system (100) to determine whether the vehicle's (1 12) weight may have changed since its last weighing. Thus, where a vehicle (1 12) has been loaded close to the maximum permitted limit, and the static scale (1 16) weighing has indicated that the vehicle (1 12) is within the maximum allowable limits, the system (100) will be able to determine whether the vehicle (1 12) exhibited behaviour which may indicate that its weight has changed since the last weighing. If the vehicle (1 12) exhibited such behaviour, and the WIM scale (1 14) reading again indicates that the vehicle's (1 12) weight falls outside the pre-determined allowable parameters, then the system (100) will direct the vehicle (1 12) toward the static scale (1 16) for a more accurate weighing. This will not only significantly increase the efficiency of control stations (106), but at the same time enable the effective overload monitoring of vehicles (1 12) and reduce the number of static scale (1 16) weighs a vehicle (1 12) may otherwise have undergone while travelling along a corridor.

It will further be appreciated that due to each control station being in communication with the server, each control station is enabled to use the information stored on the system database so as to determine whether a vehicle which has been identified by a WIM scale as possibly being overloaded should be directed to a static scale. This determination may, for example, be based on current WIM scale weight measurement data, the most recent WIM scale and/or static scale weight measurement data at a previous control station, the time of travel of the vehicle from the previous control station to the current control station as well as any other weight measurements associated with the vehicle identifier that have been stored on the system database. The determination as to whether the vehicle should be weighed at a static scale can then be made by using all these factors in an algorithm which is capable of maximizing the probability of effectively selecting overloaded vehicles while at the same time minimizing the probability of selecting vehicles that have merely been loaded very close to the maximum permissible limit, but do not exceed the limit.

It should be noted that the system and method described above also lends itself to facilitate the calibration of weighing mechanism positioned at control stations along a road transportation corridor.

Figure 4 illustrates a flow diagram of a method for calibrating vehicle weighing mechanisms (108) located at control stations (106) by making use of the system described above. At a first stage (400), the server (102) receives a plurality of data sets comprising a first weight measurement from a first weighing mechanism, preferably a WIM scale (1 14), and a second weight measurement from a second weighing mechanism, preferably a static scale (1 16). Each of the data sets will thus include a weight measurement of a vehicle (1 12) both from a WIM scale (1 14) and a static scale (1 16).

At a next stage (402), the server (102) computes the difference between the first weight measurement and the second weight measurement for each data set, after which, and at a next stage (404), the server (102) computes an average of the differences computed during the previous stage (402). Taking into consideration that the sets of weight measurements obtained will represent a range of different values, the combination of averaged differences will comprise a regression line that represents the relationship between the WIM scale (1 14) and static scale (1 16) measurements over the relevant range of weight values.

At a next stage (406), the server (102) calibrates the weight measurement readings of the WIM scale (1 14) by adjusting any weight measurement data received from the WIM scale (1 14) by the averaged difference corresponding to that WIM scale (1 14) value computed during the previous stage (404).

It will be appreciated that calibrating WIM scales (1 14) in accordance with the method described above, may ensure that the corrected WIM scale (1 14) readings will be more in line with weight measurement readings obtained from static scales (1 16). This may increase the accuracy of WIM scale (1 14) readings, thereby potentially increasing their reliability and enabling their use for prosecution purposes. Furthermore, the increase in accuracy of WIM scale (1 14) readings may at least partially negate the need for each control station (106) to have both a WIM scale (1 14) and a static scale (1 16). Further, due to the significant costs involved with static scales (1 16) when compared to WIM scales (1 14), the decrease in static scales (1 16) required along road transportation corridors may enable the more widespread overload control along corridors by means of WIM scales (1 14) at a lower capital cost.

It will be appreciated that the method of calibrating a WIM scale described above may, of course, also be utilized to calibrate a static scale. In this case, instead of computing a difference for each data set and then computing an average therefor, an average of all previous static scale weight measurements for the same vehicle can be computed and the static scale readings calibrate according to the computed average. It is envisaged that vehicle operators could also be permitted to communicate weight measurement data obtained from their own weighing mechanisms to the server. This could in turn increase the weighed measurement data used for the calibration procedure as described above, as well as permit vehicle operators to effectively calibrate their own WIM scales thereby avoiding possible sanctions at a static scale. The above description of the invention is by way of example only and it should be appreciated that numerous changes and modifications may be made to the embodiments described without departing from the scope of the invention. In particular, it should be noted that the system may utilise a complex set of rules and tests to determine if a vehicle should be flagged as having potentially altered its load while travelling along the corridor.

In addition, it should be noted that apart from a centralised, remotely accessible server, each control station may simply be provided with a local storage facility and communications capabilities allowing it to communicate with other controls stations along the corridor. In such an embodiment control stations may simply forward gathered vehicle identification and associated weight measurement information to subsequent control stations positioned further along the transportation corridor in the direction of the vehicle's travel, where the information may be locally stored until it is required, and decisions made by a local processor as to the progression of a vehicle through the control station can then at least partially be based on the gathered information from previous control stations. It should be appreciated that information may be shared between control stations by means of any number of wired or wireless communications technologies.

The invention in its broadest sense provides control stations with the ability to compare locally measured weight information with previously measured, potentially more accurate, weight information as measured by other control stations, in order to make more informed decisions as to whether or not it is necessary to conduct further, more detailed and time consuming, weighing of the vehicle. It will be apparent to those skilled in the art that these and numerous other changes and modifications may be made to the system described without departing from the scope of the invention.