GB2600453A

GB2600453A - Apparatus and method for repairing defects in a road surface

Info

Publication number: GB2600453A
Application number: GB2017228.4A
Authority: GB
Inventors: Clarke Timothy
Original assignee: Optical Metrology Services Ltd
Current assignee: Optical Metrology Services Ltd
Priority date: 2020-10-30
Filing date: 2020-10-30
Publication date: 2022-05-04
Also published as: GB202017228D0; WO2022090744A1; EP4237621A1

Abstract

A method of identifying and repairing road defects includes the steps of: moving a sensor apparatus over a road surface and using output from the sensor to identify defects and determine their location; providing a dispenser with multiple outlets for filler material, such as bitumen, each outlet having an independently controlled valve; using the position of the defect to selectively operate the valves to fill the defects. The sensor and dispenser may be mounted to a vehicle. The sensor may determine the depth of the defect to control the volume of filler dispensed. Selected valves may be operated to provide a peripheral seal band of filler material around a defect. A laser range finder may be used to take measurements of the road surface. An apparatus for identifying and repairing a defect comprises one or more reservoirs for holding filler material, a processor for receiving measurements from a sensor and a valve controller. The outlets may be provided in multiple offset rows.

Description

Apparatus and Method for Repairing Defects in a Road Surface The present invention relates to an apparatus and method for repairing defects in a road surface with a filling material.

The condition of roads in the United Kingdom is generally perceived to be poor. This is recognised by the public and the Government who seek to rectify the problem but have severe budgetary constraints given that there is a 10-year backlog in road repairs with an estimated cost in the region of £9.8Bn.

The current approach has been to deal with potholes once they reach a hazardous size to road users and a visible reminder of a lack of funding available for road repairs.

Repairing a pothole is carried out by filling it with a mix of an asphalt binder with aggregate, e.g. granite, and then tamping the patch material down. An improved repair can be made by cutting out the road surface around the pothole first to provide clean cuts and sealing the hole with the binder first. This process is also used to repair ravelled road surfaces. Smaller defects may be repaired using a binder alone. Often a band of binder (also referred to as a sealant) is formed around a repair to increase the strength of the repair.

AU2013101583 describes a road surface repair device that includes a dispensing hose that extends from the back of a lorry, through which gravel and liquid emulsion stored on the lorry can be discharged separately onto the road surface. A human operator standing behind the lorry can direct the end of the nozzle over a pothole and control what is discharged depending on the stage of the process. Once filled, the nozzle can be moved over the next pothole to be repaired and so on.

Notwithstanding the improvements provided by the device of AU2013101583, the process remains largely manual in nature with a single man repairing a single pothole at a time. As a consequence this approach is not practicable for the repair of the large -2 -number of small defects, e.g. those of 30mm and below which often, over time, enlargen to more hazardous pot holes.

The present invention was conceived through the inventor's endeavours to find a new approach to the repair of road defects to increase the speed at which they are repaired and thus make it feasible to repair the large number of smaller defects before they develop into a hazard for road users According to a first aspect of the invention there is provided a method of identifying and repairing defects in a road surface; the method comprising: a) moving a sensor apparatus over the road surface to take measurements of the road surface; using an output of the sensor apparatus to identify the presence of a defect and determine its location; b) providing: a dispenser having multiple outlets through which a filler material can be dispensed onto the road surface, each outlet having a separate valve associated with it, each valve being independently controllable from the other valves so that flow of filler material through each outlet can be controlled independently from the other outlets; c) moving the dispenser over the road surface with each of the multiple outlets arranged at different lateral positions relative to the direction of movement of the dispenser; d) using the position of the defect determined at a) to identify one or more of the multiple outlets that, by virtue of their lateral position(s), allow filler material to be deposited into the defect; and e) repairing the defect by: selectively operating the valves associated with those outlets identified at d), using the location of the defect determined at a) and the position of the multiple outlets in the direction of movement of the dispenser to time operation of the selected valves, to fill the defect with the filler material.

Although in theory the dispenser may be moved in the stop-start fashion between each defect (e.g. crack, hole, ravelled area etc) in a strongly preferred implementation the dispenser is mounted to a vehicle (typically self-propelled) that can travel continuously along the road whilst the dispenser operates to fill the defects. -3 -

Favourably the sensor apparatus is also mounted to a vehicle, favourably the same vehicle. In this way a vehicle travelling continuously at 5mph (-8Kph), for example, can detect and fill all defects it passes over in a Smile (-8Km) stretch of road in an hour.

The ability to selectively dispense filler material from any of the laterally spaced outlets individually allows for the simultaneous repair of multiple defects that are laterally spaced apart. This together with the automated approach to detection and repair, significantly reduces the overall time for repairing multiple defects in a road surface compared to traditional methods, makes it practicable to repair small defects, e.g. those under 30mm, before they expand into potholes.

Operating the valve may include one or more of: opening the valve from a closed position when the outlet is approaching or over the defect, closing the valve to prevent further deposition of filler material once the defect has been filled -and optionally also after a peripheral seal band has been deposited, and varying the degree to which the valve is open to vary the flow rate of filler material out of the outlet as the outlet moves over the road surface.

The timing of operation will depend on factors such as the height that the outlets are spaced above the road surface, the velocity of the filler material out of the outlet and the speed of the dispenser over the road surface.

The method may comprise using the output from the sensor apparatus to determine depth information indicative of the depth of the defect and using the determined depth information to control the volume of filler material dispensed from the selected valves into the defect. In this way the dispenser can alter the volume deposited into the defect to suit the defects volume and thereby avoid over filling or under filling the defect.

Control of the volume of filler material dispenser from an outlet may be achieved by controlling the time that the value is open and/or the degree to which k is open. -4 -

It also allows, for example, the deposition of a relatively small volume of filler material onto the road surface surrounding the defect to provide a band seal whilst depositing a larger volume of filler material into the defect itself.

In one variant, the depth information can be used to determine the volume of a defect, or a portion of the defect. The volume may then be divided by the number of outlets used to rtti the defect or portion of the defect to provide a volume of filler material to he dispensed by each of said outlets. This method works best where there is little variation in the depth of the defect and/or the filler material flows readily once dispensed.

Alternatively, a closed loop control method could use the depth information to repeatedly determine depth information during the fill process. This variant is less desirable as it is expected to slow the fill process and require mounting a sensor close to the dispenser.

The method may comprise using the output from the sensor apparatus to determine lateral depth information indicative of die depth of the defect at different lateral locations within the defect relative to the direction of movement of the dispenser, and using the lateral depth information to dispense different volumes of filler material from different outlets identified at d) in order to compensate for the variation in depth of the defect. This more sophisticated approach improves the cleanness of fill of defects, especially where the defect's depth varies significantly in the lateral direction. The volume of the defect can be subdivide the defect into portions, e.g. with each lying directly under a different outlet, the volume of each portion is calculated individually using the lateral depth information to determine the specific depth of the defect within each portion.

The method may comprise using the output from the sensor apparatus to determine longitudinal depth information indicative of the depth of the defect at different locations within the defect in the direction of movement of the dispenser, and using the longitudinal depth information to vary the volumes of filler material dispensed by -5 -one of the selected outlets as the dispenser moves over the road surface to compensate for the variation in depth of the defect.

The method may comprise providing at least a portion of a peripheral seal band around a defect by timing operation of the selected valves so that filler material is deposited onto regions of the road surface lying immediately adjacent and contiguous with the defect.

The method may comprise: f) using the position of the defect determined at a) to identify a further one or more of the multiple outlets that, by virtue of their lateral position(s), allow filler material to be deposited onto the road surface immediately adjacent and contiguous with the defect to provide at least a portion of a peripheral seal band around the defect; and g) selectively operating the valves associated with those outlets determined at f) to dispense filler material to form the peripheral seal band.

Through these two methods a continuous band can be formed on all sides of the defect.

The method may comprise using a ranging process to take measurements of the road surface. Where so, the sensor apparatus may comprise a ranger finder, for example a laser range finder, to carry out the ranging process.

To determine the location of the defect in the road surface the sensor apparatus may include an odometer comprising, for example, a rotary encoder adapted to roll over the road surface. In principle, position information could be obtained using a radio navigation system though, at present, the accuracy of commercially available systems is through to be insufficient for the current purpose.

The output of the odometer may also be used to determine the position of the outputs in the direction of travel of the dispenser. -6 -

The sensor apparatus may be mounted to the same vehicle that carries the dispenser at a position forward of the dispenser. Alternatively, though less preferably because of the difficulties in determining the position of the defects, it could be mounted to a separate vehicle that passed over the road surface at a time before the vehicle carrying the dispenser.

The outputs may be arranged in a row that extends transverse to the direction of movement of the dispenser across the road surface at b).

The outputs may be arranged in multiple rows, each extending transverse to the direction of movement of the dispenser across the road surface at b). The outlets of a first of the multiple rows may be offset along the axis of the row from the outlets of a second of multiple rows. This provides two possible advantages: the use of multiple rows increases the number of outlets that pass over the defect meaning that more filling material can be dispensed into the crack. This allows for the filling of larger defects for a given speed of travel of the dispenser over the road surface. In combination with the off-set feature, the provision of multiple rows provides a degree of resolution in deposition in the lateral direction greater than the pitch spacing between outlets in the row. This allows for more precise and thus cleaner filling of defects as compared with using a single row of outlets.

The filler material favourably comprises a bituminous material such as one or more of bitumen, rubberised bitumen and bitumen mastic, asphalt, natural and/or synthetic.

Where used for larger defects, e.g. pot holes, the filler material may include aggregate, e.g. granite chippings.

The invention may also be described in terms of a system, as such according to a second aspect of the invention there is provided apparatus for identifying and repairing a defect in a road surface, the apparatus comprising: -7 -one or more reservoirs for holding a filler material with which to fill identified defects; a dispenser having multiple outlets through which the filler material, held in the one or more reservoirs, can be dispensed onto the road surface as the dispenser is moved across the road surface, each outlet having a separate valve associated with it; the dispenser being adapted such that whilst it is being moved over the road surface to dispense filler material, each of the multiple outlets lie at different lateral positions relative to the direction of movement of the dispenser; a sensor apparatus adapted to i) take measurements of the road surface as it is moved across the road surface; and monitor position of the outlets in the direction the dispenser is moved across the road surface; and a processing means adapted to: a) use the measurements of the road surface taken by the sensor apparatus to identify the presence and location of the defect; and 1)) identify one or more of the multiple outlets that, by virtue of their lateral position(s), allow filler material to be deposited into the defect; and; a valve controller adapted to selectively operating the valves associated with those outlets identified at b), using the location of the defect in the road surface determined at a) and the position of the outlets from ii) to time said operation of the selected valves to fill the defect with the filler material.

The invention will now be described by way of example with reference to the 20 following Figures in which: Figures 1A and 1B are plan and side elevations of a vehicle carrying apparatus for identifying and repairing defects in a road surface; Figure 2 is a schematic diagram of the apparatus for identifying and repairing defects in a road surface; Figure 3 is a schematic illustrating the process of identifying and repairing defects; Figures 4A, 4B and 4C are plan, side and perspective views of the nozzle array being passed over the road surface to fill defects, illustrating how multiple defects can be filled simultaneously; -8 -Figures 5A and 5B illustrate nozzles over a defect to show schematically two methods of filling the a defect; and Figures 6A, 6B and 6C illustrate variant nozzle arrangements of the nozzle array system.

With reference to Figures IA and 1B there is shown a self propelled vehicle 1 carrying apparatus for identifying and repairing defects in a road surface.

The vehicle 1 is shown travelling along a lane of a metalled road 2 (also known as a sealed or paved road). An upper surface 2A of the road 2 on which the vehicle's 1 wheels roll is provided by a layer of tarmac (also known as asphalt concrete) or concrete.

The apparatus comprises a defect identification system 10 and a defect repair system 20. Whilst the vehicle 1 is in motion one or more sensors 11 of the defect identification system 10 scan the road surface 2A to identify and locate defects 3, e.g. cracks, potholes and areas of ravelling. Information of the detected defects 3 is passed to the defect repair system 20 that includes a nozzle array 21 (or array of other suitable form of outlets) through which a filler material is ejected to fill the detected defects 3. Because the vehicle 1 remains in motion both whilst identifying and filling the defects 3, a comparatively large number of defects, including small defects, i.e. under 30mm, can be repaired relatively quickly compared with traditional methods.

The filler material may include, for example: a bituminous material e.g. bitumen, emulsion bitumen, asphalt; other mastics; aggregate or a combination thereof.

Fig 2 illustrates, schematically, the defect identification system 10 and the defect repair system 20 in greater detail. The defect identification system 10 comprises, in addition to the one or more sensors 11, a crack detection processor 12. The crack detection processor 12 may be implemented by suitably programmed computer hardware using techniques known to those in the art of metrology by ranging. -9 -

The crack detection processor 12 uses the outputs from the one or more sensors 11, in this example laser ranging sensors, together with an output of an odometer 30 to identify and determine the position of defects 3 in the road surface 2A.

The odometer 30 comprises an encoder wheel arranged to roll along the road surface whilst the vehicle 1 is in motion to give longitudinal position information, i.e. position in the direction of movement of the vehicle.

The defect repair system 20 comprises, in addition to the nozzle array 21 -which is mounted behind the sensors 11 (relative to the direction of travel of the vehicle 1), a control system 22, a reservoir 23 for holding the filler material to be deposited on the road 2 via the nozzle array 21, a pump 24 and a bank of valves 25.

The control system 22 comprises a defect fill processor 26 and a valve controller 27 which is connected to each valve 25A of the bank of valves via control lines 28.

Flow of filler material from the reservoir 23 out of the nozzle array 21 is regulated by the bank of valves 25. Each valve 25A of the bank of valves 25 is associated one-to-one with a different nozzle 21A of the nozzle array 21. In this way, under control from the valve controller 27, via control lines 28, each nozzle 21A can be opened and closed independently from the others in the nozzle array 21.

The defect fill processor 26 uses the received information of defects from the defect identification system 10 together with the output from the odometer 30 to determine a) which nozzles 21A of the nozzle array 21 will pass substantially directly over the defect, b) the timing to open and close the valves 25A associated with the nozzles 21A identified at a) to deposit filler material into the defect 3 and/or immediately surrounding the defect to form a band seal, and c) volume information of the defect 3 to derive the volume of filler material that needs to be dispensed to fill the defect 3.

To provide prompt and reliable ejection of filler material from each nozzle 21A when its corresponding valve 25A is open, the filler material is pressurised within the reservoir 23 by the pump 24.

-10 -With reference to Figs 3 and 4, the laser ranging sensor(s) 11 are adapted to take distance measurements to the road surface 2A at multiple points along a detection line 100 lying transverse to die direction of travel of the vehicle 1.

The ranging measurements about the line are used by the crack detection processor 12 to generate a geometric profile of the road surface along the detection line 100 and uses the geometric profile to: identify the presence of one or more defects 3A,3B within the road surface suitable for repair by filling, for each determines the position of opposing sides Al, A2, B1, B2 of the defect along line 100, and depth profile along the line 100. This information is passed onto the defect fill processor 26 together with the longitudinal position information of the detection line 100, i.e. its position in the direction of travel M of the vehicle 1 provided by or derived from the odometer 30. This is repeated as the detection line moves in the direction of travel.

The nozzles 21A of the array of nozzles 21 are arranged in a line (one-dimensional array) that runs substantially parallel (not essential but simplifies processing significantly) with the detection line 100 to provide a notional fill line 200 travelling behind the detection line 100. As the spacing between the detection line 100 and fill line 200 is fixed and known, the longitudinal position of the fill line 200 in the direction of travel M can be determined at any time using the output of the odometer 30.

With the relative positions of the individual nozzles along the fill line 200 known, the defect fill processor 26 deteimines for each defect 3A, 3B detected at each longitudinal position, which nozzles 21A will pass directly over the defect 3A, 3B. This is used to instruct the valve controller 27 as to which valves 25A to open, with the output of the odometer 30 used to time sending of the instructions to the valve controller 27 or for use by the valve controller 27 as to when to act on the instructions.

As the nozzle array 21 passes over a defect 3A, 3B, the valve controller 27 selectively opens valves 25A associated with nozzles 21A identified to pass substantially directly over the defect(s) so that filler material is ejected from the reservoir 23 through the open nozzles 21A into the defects 3A 3B to fill it.

Often the defects 3 will have a dimension in the direction of movement of the vehicle 1 that is greater than the longitudinal spacing between ranging measurements and thus geometry is represented through multiple lines of ranging measurements. Thus the process of scanning and filling the defect comprising subdividing the defect into multiple longitudinal portions each of which can have a different position, width and depth which is compensated for by varying the amount of filler material dispensed through a nozzles as it passes over the defect and/or opening and/or closing different nozzles to take into account changes in the width and/or lateral position of the defect in the longitudinal direction.

Because filler material can be ejected selectively through any selection of nozzles it is possible to fill any number of separate defects that extend across the fill line si multaneously.

Often it is desirable to deposit a band 5 of the filler material or other sealant around the defect to provide a more robust repair.

To form the portions of the band 5 lying in front and behind the defect (from the perspective of the motion of the array 21) the timing of the valves associated with the outlets to fill the defect can be adjusted in order that filler is deposited on the road surface in front and behind the defect 3 as well as in it.

The volume of filler material required per unit area to provide a band is usually smaller than that needed to fill a defect as the hand often needs only to he 2-3 mm thick. Therefore the volume of filler deposited through each outlet is favourably changed as the nozzles move longitudinally between when depositing the band and filling the defect.

-12 -To form portions of the band 5 lying lateral to the sides of the defect the defect fill processor 26 uses the received information of defects 3 from the defect identification system 10 together with the output from the odometer 30 to determine a number of further nozzles immediately adjacent those selected to fill the defect, that by virtue of their position in the array allow them to deposit filler material in a region lying either side of the defect.

There are different methods by which filler material can be distributed through the open nozzles to fill the defect.

In one variant, as illustrated in Fig 5A, the total volume of a section of each defect occurring on the detection line is determined. This is calculated from the length of the defect along the detection line 100, its depth (an integration function can be used to account for the likelihood of the depth varying along the detection line 100) and the width of the fill line 100 -which may be, for example, a value corresponding with the spacing (or a multiple thereof) between ranging measurements in the direction of motion of the vehicle 1. The total volume calculated is divided by the number of nozzles 21A determined to he directly over the defect and the resultant amount dispensed out of each of said nozzles 21A. The method relies on the filler material being fluid enough to flow within the defect once dispensed, to level out where the depth of defect is not uniform across the fill line 200.

With reference Fig 5B, in an alternative variant the total volume of the section of the defect along the fill line is subdivided into portions (V1, V2, V3, V4, VS, V6) each lying under a different nozzle 21A. The volume of each portion (V1, V2, V3, V4, VS, V6) is calculated separately using the pitch spacing P between nozzles 21A along the fill line 200 as the length dimension, the depth profile within the subdivision, and the width of the fill line as dimensions. This provides a set of different volume values for the nozzles 21A of the array.

These values are used to individually control the volume of filler material ejected from each nozzle 21A based on the volume of its corresponding portion. This second -13 -variant is considered superior to the first as it provides a cleaner fill without relying on the filler material to flow once dispensed.

There a number of means to control the volume of ejected filler material from a nozzle. One method is to control the time that the valve is open, determining the volume based on an expected flow rate through the nozzle. An alternative method is to vary the flow rate through the nozzle through one or more of: controlling the extent to which the valve is open and/or and varying the pressure of the filler material individually at each nozzle. The latter method requires a set of individually controllable pressure regulators, associated one-to-one with each of the nozzles so that the pressure of filler material can be adjusted individually at each nozzle independently from the rest.

Figs GA, 6B and 6C illustrate variant arrangements of nozzle array. As previously described, in one embodiment, illustrated in Fig 6A, the nozzle array comprises a single row (i.e. one dimensional array) of nozzles 21A that extend in a line running transverse to the direction of travel of the vehicle. With a single row of nozzles the precision of placement of filler material along the fill line is limited to the pitch spacing between the nozzles.

Fig 6B illustrates a variant embodiment comprising two parallel rows R1. R2 of nozzles 21A. The rows are spaced apart in the direction of movement of the vehicle. The pitch spacing between nozzles within each row is the substantially the same. The lateral positions of die nozzles 21A of die first row RI along the fill line are offset from the lateral positions of the nozzles 21A of the second row R2. The system is adapted to select which nozzles from which rows operate allowing for greater precision in the positioning of filler material. This allows for cleaner filling of narrow cracks, and of the edges of larger cracks, that fall between nozzles of the first row.

Figure 6C is a further variant that extends this principle to provide still better precision by providing four rows RI, R2, R3, R4. The lateral position of the nozzles of each of the four rows R1, R2, R3, R4 along the fill line are offset to the nozzles of -14 -all of the other rows. It will be appreciated that any number of rows may be employed.

Because nozzles from different rows can dispense filler material at a similar lateral position, the provision of multiple rows of nozzles allows for a greater volume of filler material to be dispensed into the defect for a given speed of the vehicle. For example, taking the example of Fig 5B, in an instance in which the volume of a portion (V1, V2, V3, V4, VS, VG) is calculated to be greater than which can be filled by a single nozzle in the time available (a function of the speed of the vehicle), the system may cause one or more nozzles of the second, third or fourth row that also pass over the portion (V1, V2, V3, V4, VS, V6) to dispense an amount of filler material in additional to the corresponding nozzle of the first row, so that the required volume of filler material to file the portion is dispensed.

It will be appreciated that it is not necessary for the nozzles of rows to be offset to provide this benefit.

In the afore described examples the one or more sensors 11 are laser rangers though other suitable rangers or sensor using means other than ranging could be used instead. For example one or more cameras may be used to generate images of the road surface that could be processed by image processing software of the detection system 10 to identify features that correspond with a road defect. In one embodiment a camera could be used in conjunction with a laser ranger to provide a means to validate detections made using the laser ranger.

It is preferred that the nozzles are arranged in one or mull ple rows but this does not need to be the case so long as their relative lateral and longitudinal positions are known.

Depending on the angle of attack of the nozzles to the road surface, the nozzles may not need to pass directly over the defect in order to deposit filler material into it.

Claims

-15 -Clai ms I. A method of identifying and repairing defects in a road surface; the method comprising: a) moving a sensor apparatus over the road surface to take measurements of the road surface; using an output of the sensor apparatus to identify the presence of a defect and determine its location; 1)) providing: a dispenser having multiple outlets through which a filler material can be dispensed onto the road surface, each outlet having a separate valve associated with it, each valve being independently controllable from the other valves so that flow of filler material through each outlet can be controlled independently from the other outlets; c) moving the dispenser over the road surface with each of the multiple outlets arranged at different lateral positions relative to the direction of movement of the dispenser; d) using the position of the defect determined at a) to identify one or more of the multiple outlets that, by virtue of their lateral position(s), allow filler material to be deposited into the defect; and e) repairing the defect by: selectively operating the valves associated with those outlets identified at d), using the location of the defect determined at a) and the -16 -position of the multiple outlets in the direction of movement of the dispenser to time operation of the selected valves, to fill the defect with the filler material.
2. A method according to claim comprising 1 using the output from the sensor apparatus to determine depth information indicative of the depth of the defect and using the determined depth information to control the volume of filler material dispensed from the selected valves into the defect.
3. A method according to claim 2 comprising using the output from the sensor apparatus to determine lateral depth information indicative of the depth of the defect at different lateral locations within the defect relative to the direction of movement of the dispenser, and using the lateral depth information to dispense different volumes of filler material from different outlets identified at d) in order to compensate for the variation in depth.
4. A method according to claim 2 or 3 comprising using the output from the sensor apparatus to determine longitudinal depth information indicative of the depth of the defect at different locations within the defect in the direction of movement of the dispenser, and using the longitudinal depth information to vary the volumes of filler material dispensed by one of the selected outlets as the dispenser moves over the road surface to compensate for the variation in depth of the defect.-17 - 5. A method according to any previous claim comprising providing at least a portion of a peripheral seal band around a defect by timing operation of the selected valves so that filler material is deposited onto regions of the road surface lying immediately adjacent and contiguous with the defect 6. A method according to any previous claim comprising: f) using the position of the defect determined at a) to identify a further one or more of the multiple outlets that, by virtue of their lateral position(s), allow filler material to be deposited onto the road surface immediately adjacent and contiguous with the defect to provide at least a portion of a peripheral seal around the defect; and g) selectively operating the valves associated with those outlets determined at 0 to dispense filler material in order to provide a peripheral seal around the defect.S. A method according to any claim 2 -7 comprising using a ranging process to take measurements of the road surface in order to identify the defect.9. A method according to claim 8 comprising using a laser range finder to carry out the ranging process.10. A method according to any previous claim wherein the filler material comprises a bituminious material.-18 - 11. A method according to any previous claim wherein the sensor apparatus and dispenser is mounted to a vehicle and the vehicle is continuously moved across the road surface during a) and e).12. Apparatus for identifying and repairing a defect in a road surface, the apparatus comprising: one or more reservoirs for holding a filler material with which to fill identified defects; a dispenser having multiple outlets through which the filler material, held in the one or more reservoirs, can be dispensed onto the road surface as the dispenser is moved across the road surface, each outlet having a separate valve associated with it; the dispenser being adapted such that whilst it is being moved over the road surface to dispense filler material, each of the multiple outlets lie at different lateral positions relative to the direction of movement of the dispenser; a sensor apparatus adapted to i) take measurements of the road surface as it is moved across the road surface; and ii) monitor position of the outlets in the direction the dispenser is moved across the road surface; and a processing means adapted to: a) use the measurements of the road surface taken by the sensor apparatus to identify the presence and location of the defect; and -19 -b) identify one or more of the multiple outlets that, by virtue of their lateral position(s), allow filler material to be deposited into the defect; and; a valve controller adapted to selectively operating the valves associated with those outlets identified at b), using the location of the defect in the road surface determined at a) and the position of the outlets from ii) to time said operation of the selected valves to fill the defect with the filler material.13. Apparatus according to claim 12 wherein the processing means is adapted to use the output from the sensor apparatus to determine depth information indicative of the depth of the defect and the valve controller is adapted to control the volume of filler material dispensed from the selected valves into the defect based on the depth information.14. Apparatus according to claim 13 wherein the processing means is adapted to use the output from the sensor apparatus to determine lateral depth information indicative of the depth of the defect at different lateral locations within the defect relative to the direction of movement of the dispenser,and the valve controller is adapted to control the valves so as to dispense different volumes of filler material from different outlets of those identified at d) based on the lateral depth information order to compensate for the variation in depth.-20 - 15. Apparatus according to claim 2 or 3 wherein the processing means is adapted to use the output from the sensor apparatus to determine longitudinal depth information indicative of the depth of the defect at different locations within the defect in the direction of movement of the dispenser, and the valve controller is adapted to control the valves associated with the sleeted outlets based on the longitudinal depth information so to vary the volumes of filler material dispensed by one of the selected outlets as the dispenser moves over the road surface to compensate for the variation in depth of the defect.16. Apparatus according to any claim 12-15 wherein the valve controller is adapted to time operation of the selected valves so that filler material is deposited onto regions of the road surface lying immediately adjacent and contiguous with the defect in order provide at least a portion of a peripheral seal band around a defect.17. Apparatus according to any claim 12-16 wherein the processing means is adapted to use the position of the defect determined at a) to identify a further one or more of the multiple outlets that, by virtue of their lateral position(s), allow filler material to be deposited onto the road surface immediately adjacent and contiguous with the defect to provide at least a portion of a peripheral seal around the defect; and the valve controller is adapted to selectively operate the valves associated with the outlets to dispense filler material in order to provide a peripheral seal around the 20 defect. -21 -18. Apparatus according to any claim 12 or 17 wherein the outlets are arranged in a row that extends laterally to the direction of movement of the dispenser across the road surface.19. Apparatus according to claim 18 wherein the outlets are arranged in multiple rows, each row extending transverse to the direction of movement of the dispenser across the road surface.20. Apparatus according to claim 19 wherein the outlets of a first of the multiple rows, are offset along the axis of the row from the outlets of a second of multiple rows.21. Apparatus according to any claim 12-20 wherein the sensing apparatus comprises a rangefinder adapted to take the measurements of the road surface.22. Apparatus according to any claim 12-21 wherein the sensing apparatus comprises an odometer adapted to output position information; and that the processing means is arranged to use the output position information from the odometer to determine the location of the defect and/or monitor the position of the multiple outputs in the direction of movement of the dispenser.23. Apparatus according to claim 22 wherein the odometer includes an encoder wheel adapted, when in use to roll along the road surface.