GB2270533A - Traffic control unit - Google Patents

Abstract

A traffic flow control unit which when located upon a road surface will permit traffic flow in one direction relative thereto but prevent traffic flow in the opposed direction, the unit comprising a rigid container, a flow control plate (24), pivot means in the container for the control plate, the flow control plate projecting from the container and pivotable between a first operative condition and a second inoperative condition, and resilient bias means urging the flow control plate towards the first operative condition. The bias means comprises a pair of torsion springs (172) located on a pivot pin (54). The ends of the springs abut the underside of the plate. The container has a cover plate (244) which can be removed with the pivot and flow control plate. <IMAGE>

Description

TRAFFIC FLOW CONTROL UNIT This invention relates to a traffic flow control unit, and in particular to a traffic flow control unit intended to encourage one-way flow of vehicular traffic along selected traffic lanes, and/or to be a deterrent to vehicles seeking to use "no entry" traffic lanes.

There are many occasions on which the authorities wish to ensure one-way vehicle traffic flow, without the need for constant supervision; thus the entrance to a hospital car park at visiting hours, and the entrance to a factory or school car park at normal starting and leaving times, can become severely congested if vehicles are trying both to enter and to leave through that "entrance", instead of leaving through the intended exit. Commercial car parks, with payment made according to the length of stay, need often to be patrolled at all "entrances" as well as at all "exits", since some motorists have been known to seek to leave by an "entrance" to avoid payment.

To help solve these problems, there has for many years been available a traffic flow-control unit including a plate which is normally upstanding to act as a barrier to a vehicle wheel, but which is able to pivot in one angular direction under the weight of the vehicle wheel to permit that vehicle to pass in the authorised direction. However the known units require considerable road excavation, which is not always convenient or desirable.

Thus we are aware of British patent 1,261,704 which teaches an automatic vehicle barrier comprising a pivoted plate, mounted in a box, to be embedded in the ground Because it is to be embedded, installation and removal both require extensive ground excavation. The pivoted plate extends througgh an open-sided slot in a cover for the box.

We seek to avoid or reduce this disadvantage. Thus we provide a traffic flow control unit which comprises a rigid container, a cover for the container, a traffic flow control plate, pivot means for the traffic flow control plate mounted in the container, the plate extending through the cover and outwardly of the container, and securement means for location of the container at a selected position along a vehicular route, the securement means including a leg extending away from the container and in a direction substantially parallel to the cover, the leg being firmly connected to the container. Such unit can be of substantially reduced depth, and possibly also of reduced fore-to-aft length.Preferably the plate is resiliently biassed to the normal "upright" rest position by a torsion spring, but a helical coil spring can alternatively be fitted around dimples on the plate and rear leg i.e. the leg towards which a fitted plate moves when contacted by a vehicle wheel.

Furthermore the known units are not suited for short-term adaptation, as may typically be required for controlling traffic only during rush periods, but not at other times. We thus disclose the use of an assembly of units according to the invention, mounted on a removable plank or equivalent. Such mounting becomes practical with the reduced depth units according to the invention, particularly since a unit does not provide a high barrier to traffic flow in the authorised direction.

The invention will be further described by way of example with reference to the accompanying drawings (not to scale) in which: Fig.l is a plan view of a traffic lane with five traffic flow control units fitted, the lane also having a raised portion to slow vehicle flow prior to the vehicles meeting the traffic flow control units; Fig.2 is a schematic side sectional view of a known traffic flow control unit fitted into a traffic lane; Fig.3 is a schematic view looking back towards an array of flow control units constructed according to Fig.2; Fig.4 is a perspective view of the flow control unit of Fig.2; Fig.5 is a perspective view of one embodiment of traffic flow control unit according to the invention; Fig.6 is a schematic side view of the unit of Fig.5 fitted in position in a traffic lane;; Fig.7 is a schematic side view of another embodiment of traffic flow control unit according to our invention; Fig.8 is a schematic side view of an alternative embodiment of traffic flow control unit; Fig.9 is a perspective view of the embodiment of Fig.8; Fig.10 is view, from underneath, of the traffic flow control plate as used in the known embodiment of Figs.2/4; Fig.ll is a view from underneath of the traffic flow control plate according to the invention, and suitable for use in the embodiments of Figs.5,7 and 8.

Fig.12 is a perspective view of another embodiment; and Fig.13 is a part-section of the container and plate of Fig.12.

Traffic lane 10 has been designated as one-way traffic flow lane, with post 12 having a sign 14 indicating permitted flow and sign 16 indicating forbidden flow. Thus the traffic flow is intended to proceed in the direction of arrow 18.

A raised portion 20 of lane 10 is intended to slow traffic flowing in the direction of arrow 18, prior to a vehicle reaching the array of traffic flow control units 22, and so acts as a "silent policeman".

As shown in Fig.l, five traffic flow control units 22 are sunk into the surface of traffic lane 10, and as indicated in Fig.2 the upstanding control plate 24 forming part of each such unit 22 is arranged to pivot downwardly towards the surface of lane 10 (in the direction of arrow 26) when contacted by the wheel of a vehicle (not shown) travelling in the permitted direction of arrow 18.

Plate 24 is weighted by extension arm 30 located in a hollow container 32 (Fig.4), and to the other side of pivot 34 from plate 24. Extension arm 30 includes at its end remote from the pivot 34 a wear-resistant and impact-resistant block 36 of a rubber compound, adapted respectively to engage rear wall 38 of container 32 in the normal position shown, and a cross strut 40 welded to container sides 42 when the plate is fully pivoted by the weight of a vehicle wheel.

In normal use, the container 32 upper opening is closed by a cover plate 44 having three screw holes 46 in alignment with corresponding tapped holes in cross struts 47 welded to the internal wall surfaces of container 32; in an alternative embodiment more screw connections are provided. The underside of cover plate 44 carries a pair of blocks 45 (Fig 1O,Fig.ll), each having a through-bore facing and aligned with the other to receive a pivot shaft or pin 54, the pivot shaft in use being retained between the side walls 42 of the container 32.

Container 32 is sunk into a prepared hole in traffic lane 10, so that cover plate 44 is substantially flush with the surface of lane 10. Traffic lane 10 will conventionally be of concrete 48, but with an area below container 32 providing a hard core soakaway 50 to permit the escape of rainwater etc collected within container 32. In a typical example, container 32 is of steel, primed and finished in a bitumastic based paint, and has a depth of 204mm and a width of 216mm; flow plate 24 extends (at an angle of about 60 degrees) above the lane 10 by a height of 115mm. In part, the depth of the container is determined by the need to accommodate extension 30, whilst the fore-to-aft dimension (right to left as viewed in Fig.2) is determined by the need to accommodate the swing arc of extension 30.The "silent policeman" 20 will usually have a height of 75mm and a width in the direction of arrow 18 of 610mm, and be spaced 3500mm before traffic flow control units 22.

An arrangement according to the invention, as shown in Figs 5/6 uses a similar traffic flow control plate 24 and cover 44 to those of Fig.4, the cover 44 in this embodiment closing off the top of a container 132. Control plate 24 has however a substantially reduced extension 302 (Fig.l3), or no extension (Fig.ll). Container 132 is of substantially reduced depth compared to container 32, with in the Fig.6 embodiment substantially less excavation (if any) or with preparatory surface treatment required, and with reduced risk of puncturing a water-resisting membrane if fitted.To prevent the unit being lifted from the lane 10 by the weight of the vehicle wheel on control plate 24, the sidewalls 142 of container 132 are of angled sections, with a vertical wall 142a and an outwardly directed substantially horizontal leg 142b, the horizontal legs 142b each receiving a pair of bolts 144 which are sunk into the surface of traffic lane 10 i.e. into the concrete or equivalent.

In the alternative embodiment of Fig.7, the traffic flow control unit is surface mounted i.e. its base is flush with the level of traffic lane 10. For some applications it may be acceptable for the vehicle to ride up the small height of sidewall 142a and cover plate 44, as an extra "silent policeman", or deterrent to fast driving; but we prefer to provide an angled ramp 152 bolted to the front wall 142a of container 132 by bolts 154.

At the exit or rearward or trailing end of the traffic flow control unit 122, in the embodiment shown in Fig.6 I permit traffic flow control plate 24 to pivot in the direction of arrow 26 until it meets and is supported by the surface of traffic lane 10. However, in the embodiment of Fig.7, the rear or trailing horizontal leg 142b has an extension 160; the trailing edge 156 of traffic flow control plate 24 rests upon (abuts) this extension 160 when biassed by the weight of a vehicle wheel, to limit the pivotal movement of the control plate.A further advantage of extension 160 is that a vehicle approaching the flow control unit from the unauthorised (anti-flow) direction will weight down this extension 160 before abutting traffic flow control plate 24, and so its own weight will help prevent plate 24 from lifting the traffic flow control unit from the surface of traffic lane 10. In an alternative embodiment, trailing leg 142b has fixed thereto extension 160 rather than being integral therewith.

Figs 8/9 are of an alternative arrangement to that of Fig.7.

Cover plate 244 is of extended length in the direction opposed to the direction 18 of authorised flow, and is deflected downwardly as seen in Fig.8 to form integral ramp 252, and a ground engagement section 253. As viewed, the container has upper and lower levels, the cover being secured to the container at the upper container level, and with an extension which is downwardly deflected to include a portion 253 parallel to the plane of the lower container level; in use the portion 253 is a ground engagement section and forms part of the securement means, with holes which are countersunk so that the heads of bolts 144 are not contacted by the vehicle tyres.In this embodiment, plate 160 is an extension of trailing horizontal leg 142b, being welded thereto at edge 161r but in an alternative embodiment, plate 160 extends below and to each side of the sidewalls 142a of container 232, with vertical arms 142a being welded to plate 160.

Fig 10 is a view from underneath the traffic flow control plate 24 of Figs.1-4. It will be noted that the plate includes a hollow member 170 in which pivot shaft or pin 54 is received, and with which or about which control plate 24 can pivot; the pivot pin 54 is located in the bores of the members 45 carried below and by (non-rotatable) cover plate 44.

Fig.ll is of the similar traffic flow control plate 24 according to the invention. The arm 30, abutment 36 (and so also cross-member 40) connected to the plate 24 of Fig.2 are omitted since they are no longer necessary, the automatic return of traffic flow control plate 24 to the upstanding position of Fig.5 being now effected by a pair of torsion springs 172 located around the ends of pivot pin 54.

As seen in Fig.ll, the inner end of each torsion spring 172 extends below and is in contact with the underside of traffic flow control plate 24, whilst the outer end extends below and is in contact with the underside of cover plate 44. In the embodiment shown, the axial space for torsion springs 172 is provided by shortening pin location members 45; but in an alternative embodiment the hollow member 170 can be shortened; or pin 54 can be lengthened. Although we prefer to return traffic control plate 24 to the upright position after the vehicle wheel has passed therebeyond by means of a torsion spring, other resilient means can be used e.g. an annular compression spring between leg 142b and control plate 24, located by dimples from the control plate lower surface (when pivoted by vehicle weight) and rear leg, the dimples projecting within the spring coils.It would also be possible to operate the control plate by direct means such as a reversible electric motor having a shaft with extended and retracted positions.

In an alternative embodiment, the inner end of each torsion spring can be located in a pocket below control plate 24 to protect it from inadvertent damage or vandalism; and in a further alternative (converse) embodiment the outer end of torsion spring 172 can engage the underside of plate 24.

Fig.l2 is of an embodiment generally similar to that of Fig.9 but with a container 300 shorter in the fore-to-aft direction.

Thus the extension 252 of the cover plate 244 is not supported between the container 300 and the ground-engagement section 253.

The left and right sidewalls of the container do not have lateral flanges. The control plate extends through an open-sided slot in the cover, with flanges at each side of the plate.

As a particular feature, the container has a lower cross-strut 301 (Fig.13) forming the back-stop for the control plate, the control plate for this purpose having an extension 302 of reduced length. An advantage of this embodiment is that the front edge 245 of the control plate aperture 303 in the cover 244 need not be used as the back-stop, with the unit therefore usually being considerably quieter in use e.g. in hospital driveways. One free end of the torsion spring 272 is located in an aperture 304 in the rear wall 305 of the container, whilst the other free end engages the underside 306 of control plate 24.

The control plate has a deep recess at 310, so that in the "lay-flat" condition which the control plate adopts when weighted by a vehicle, there is a gap between the control plate and the trailing (rear) edge of the container adjacent each of the left and right sides of the container; these gaps can be used if required to receive locking means to hold the control plate in the inoperative (lay-flat or non-obstructing) condition.

Our arrangement permits the provision of a lighter traffic flow control unit, and at much lower unit cost (since less material is required), and with a reduced installation cost, and with a wider range of applications than the known units which have to be sunk deep into the surface of the traffic lane. Specifically, the surface mounted unit of Fig.7, or the near-surface mounted unit of Fig.6, require minimum excavation or interference with the existing traffic lane e.g. road surface. Thus units can be easily laid down, and if necessary removed and placed elsewhere, without substantial repair work being required to the road surface. The difficulty of withdrawing container 32 from a concrete lane base is avoided. Provision for drainage is not required.

We also foresee that the traffic flow control unit according to the invention greatly extends the possible use of such units, into locations for which they have previously not been thought suitable, specifically in multi-story car parks. Thus multi-storey car parks have relatively shallow decks; one long-standing problem of the the known unit of Fig.2/4 is that the container 32 can project through the deck. An equally serious problem, even with thicker decks, is that the plastic waterproofing membrane is punctured and damaged, usually over a significant area, thus destroying the water-proofing of the deck or allowing water to enter to cause frost damage in cold weather. For many multi-storey car parks, a suitable location for the array of known control units is on an upward incline, but with the arrangement of Fig.2 the traffic flow control plate 24 can pivot under the action of weighted arm 30 too near to the plane of traffic lane 10 to deter intending counter-flow traffic.

An assembly of the traffic control units e.g. of metal, can be mounted on a plank e.g. of wood for temporary use, such as to control traffic entering a particular traffic lane from a specified direction during busy periods. In such embodiment the plank would be secured either directly to the traffic surface as by countersunk bolts, or indirectly as by being slid under hoops to each side of the traffic lane, the assembly in each case being removable and replaceable without need to dismantle the units from the plank or equivalent mounting component.

Claims (11)

1. A traffic flow control unit comprising a rigid container, a flow control plate, pivot means in the container for the control plate, the flow control plate projecting from the container and pivotable between a first operative condition and a second inoperative condition, and resilient bias means urging the flow control plate towards the first operative condition.

2. A unit as claimed in Claim 1 in which the container has a removable cover, the cover mounting the pivot means

3. A unit as claimed in Claim 1 or Claim 2 in which the resilient bias means comprises a torsion spring with one terminal end engaging the flow control plate and the other terminal end engaging the container.

4. A unit as claimed in claim 3 in which said other end locates on an internal surface of the container.

5. A unit as claimed in Claim 3 or claim 4 in which the flow control plate includes a hollow member in which is received part of a pivot pin, the torsion spring having coils intermediate the said one terminal end and the said other terminal end, the coils surrounding part of the pivot pin.

6. A unit as claimed in Claim 5 in which the pivot pin is of a length greater than that of the hollow member whereby both ends of the pin are adapted to extend out of the hollow member, non-rotatable pin-location members aligned with the hollow member, the pin ends being rotatably mounted in the pin-location members, the coils of respective torsion springs being between the hollow member and each said pin-location member.

7. A unit as claimed in any of claims 2-6 in which the cover mounts the flow control plate and the resilient bias means whereby removal of the cover effects simultaneous removal of the flow control plate and resilient bias means.

8. A unit as claimed in any previous claim in which the container includes a cross-strut, the control plate having an extension which in the said first operative condition is engaged with the cross-strut whereby the cross-strut forms a back-stop for the control plate.

9. A traffic control unit constructed and arranged substantially as described with reference to Fig.5 or Fig.7 or Fig.8 or Fig.l2 of the accompanying drawings.

10. A flow control plate for use in a unit as claimed in any previous claim which mounts a torsion spring.

11. A flow control plate constructed and arranged substantially as described with reference to Fig.ll or Fig.l3 of the accompanying drawings.