AU678224B2

AU678224B2 - A Grating

Info

Publication number: AU678224B2
Application number: AU63237/94A
Authority: AU
Inventors: Philip Graham Breene
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-05-20
Filing date: 1994-05-20
Publication date: 1997-05-22
Anticipated expiration: 2014-05-20
Also published as: AU6323794A

Description

I I P/00/011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT e o s a o o r o Name of Applicant: Actual Inventor: Address for Service: PHILIP GRAHAM BREENE Philip Graham Breene

INTELLPRO

Patent Trade Mark Attorneys 13th Floor, 379 Queen Street BRISBANE, QLD, 4000 (GPO Box 1339, BRISBANE, 4001) "A Grating" Invention Title: Details of Associated Provisional Application No: The following statement is a full of performing it known to me: Australian Patent Application No. PL8909 filed May 1994.

description of this invention, including the best method THIS INVENTION relates to a grating and in particular but not limited to a roadway drainage grating suitable for use in conjunction with, and adjacent to, a roadway curb or raised median for collection of water flowing along the roadway.

Roadway drainage gratings are known which have a plurality of spaced water flow through slots which, in use, extend in the direction of water flow along the grating which is also the direction of traffic flow along the roadway.

In use, the grating is located above a gully pit of an underground stormwater drainage system. The grating is customarily of a "drop in" type in that it drops into a frame and is removed completely to open and give access to the gully pit.

This type of grating has high hydraulic efficiency but is unsafe because thin bicycle tyres (20mm 25mm wide) can pass through the slots, thus this form of 0 to, :o grating potentiates injury to cyclists.

o* Most forms of roadway drainage gratings include a plurality of slots which, 15 in use, are set transverse to the direction of water flow but these have low O hydraulic efficiency. Due to turbulence adjacent the slots, water tends to skip i: across the grating.

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In the main part, prior gratings have been designed having regard primarily to achieving high hydraulic efficiency without considering safety and environmental issues. Many existing gratings actually appear unsafe with large openings predominating and constructions which, generally speaking, do not "blend" into the roadway surface to any useful degree. These gratings are generally "unfriendly" both in action and appearance which makes existing gratings environmentally unsatisfactory.

(.~o9 i IIl In addition, present gratings with bars tranwverse to the traffic flow have an undesirable sound when driven over. A car driver normally hears a clearly audible rumble which in itself attracts an adverse emotive response from the driver.

It is an object of the present invention to alleviate at least to some degree the aforementioned problems associated with the prior art.

In one aspect therefore, the present invention resides in a grating suitable for use adjacent a curb or raised median of a roadway to intercept water flowing along the roadway, the grating having an upper surface defined by a plurality of narrow interdigitated closely spaced slots and bars which, in use, are arranged in the normal direction of water flow over the grating to optimise hydraulic efficiency, the slots being narrow enough so that a bicycle having tyres ranging S.from 20mm to 25mm in width can safely travel over the grating in the direction the slots, the bars being arranged at 22 to 30 bars per metre with a slot width 15 of not greater than 25mm and not less than The grating is preferably cast iron and each bar is preferably T-shaped in transverse profile having a flange and web. The web being tapered and having a median width approximately half the width of the flange.

The grating preferably has a single cross-bar positioned about halfway S 20 along the grating, thereby separating the grating into two spaced sets of slots and bars. The cross-bar has an upper surface which is typically contiguous with the upper surface of the grating or is recessed below the upper surface of the grating.

Typically, the grating is positioned in a frame just below the grad, fevel of a roadway so that the grating with its closely spaced bars give the appearance of blending into the roadway.

The bars and slots can range in relative width with the bars and slots being about the same width, although the bars are typically slightly wider than the slots.

The bars and slots are typically all the same size and uniformly distributed over the surface of the grating although this need not be the case.

Typically, when the slots and bars are about the same width, the bars are arranged at from about 22 to 30 bars per metre with a tyre penetration depth into a slot of a maximum of 5mm where a 25mm diameter tyre is at 400kPa inflation on a 686mm diameter wheel under a 50kg load and positioned vertically over a 1 0 slot.

Typically, slot widths range from 10mm to 25mm with the larger width being appropriate in regions where tyre width of less than 23mm are not common. In such cases, 10mm to 23mm is used with 15mm to 20mm being S°optimum.

1 5 The grating is typically manufactured using a mould made of two mould portions. The flange section of the bars being moulded in one portion while the web is moulded in the other portion so that surface finish on the upper surface S"of the grating can be improved.

In order that the invention can be more readily understood and be put into practical effect, reference will now be made to the accompanying drawings and wherein:- Figure 1 is a plan view of a grating according to the present invention; Figure 2 is an end view of the grating of Figure 1; Figure 3 is a section through 3-3 of the grating of Figure 1;

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Figure 4 is a part section through a grating assembly employing the grating according to Figure 1 showing the grating arranged in a supporting frame; and Figure 5 is a part section through the grating assembly of Figure 4 showing in more detail the transverse profile of the bars of the grating.

Referring to the drawings and initially to Figures 1 to 3, there is illustrated a grating 10 suitable for use adjacent a curb or raised median (not shown) of a roadway (not shown) to intercept water flowing along the roadway, the grating has an upper surface 11 defined by a plurality of narrow interdigitated closely spaced slots 12 and bars 13 where in this case, the slots and bars are about the same width. In use, the grating is arranged so that the slots and bars 12 and 13 are positioned in the direction of water flow along the grating to improve hydraulic efficiency. In the illustrated embodiment, the slot width is 17mm S-whereas the bar width is 21mm.

As most bicycle tyres are 20mm to 25mm in width, the 17mm wide slots 15 provides for less than a 5mm penetration of a tyre into the slots. Under these circumstances, the use of this particular grating in a roadway is for all practical purposes imperceptible to a cyclist riding over the grating.

Each end of the grating 10 is equipped with a recess 14 which in conjunction with a spigot 15 (see Figure 5) forms a releasable hinge assembly so 20 that the grating 10 can rotate within a frame 16 (see Figure 5) and in turn be removable from the frame.

A more detailed description of this hinge assembly is provided in the applicant's co-pending Australian Patent Application No. 28417/92 and the disclosure thereof is hereby incorporated into the present specification by b, 6 reference.

The grating 10 in the illustrated embodiment includes a cross bar 17 which has the profile illustrated in Figure 3. The cross bar includes water underflow means 18 which promotes the flow of water under the bar 1 7 rather than over the bar. While the bar 17 in the illustrated embodiment has a surface 19 disposed contiguous with the surface 11 of the grating, the surface 19 can be recessed below the surface 11 again to improve flow through the grating.

For a more detailed description of the underflow surface 18, reference can be made to the applicant's co-pending Australian Patent Application No.

28416/92 and the disclosure thereof is hereby incorporated into the present specification by reference.

~Referring now to Figures 4 and 5, the grating 10 is shown disposed in a S- frame 16 and as can be seen in Figure 5, each of the bars 13 is generally Tshaped in profile having a flange portion 20 and a web 21 and in the illustrated 1 5 embodiment, the flange is 21mm wide while the web tapers from a maximum width of 10mm down to 6mm.

Due to the relatively large number of bars and spaces (in this case 1 7mm spaces), the width of the webs 21 can be made relatively thin as shown in Figure oe i 5 and this relative thinness makes for a stronger casting resulting from faster 20 cooling in the casting process.

The process of casting envisaged in the present invention involves casting the flange 20 in an upper portion of a mould and casting the flange 21 in a lower portion of the same mould. What this means is the finish on surface 11 can be optimised.

I 7 Whilst the above has been given by way of illust:ative example of the present invention, many variations and modifications thereto will be apparent to those skilled in the art without departing from the broad ambit and scope of the invention as set forth in the appended claims.

a e d e ie 6 See us -sesk~'

Claims

1. A grating suitable for use adjacent a curb or raised median of a roadway to intercept water flowing along the roadway, the grating having an upper surface defined by a plurality of narrow interdigitated closely spaced slots and bars which, in use, are arranged in the normal direction of water flow over the grating to optimise hydraulic efficiency, the slots being narrow enough so that a bicycle having tyres ranging from 20mm to 25mm in width can safely travel over the grating in the direction of the slots, the bars being arranged at from 22 to 30 bars per metre with a slot width not greater than 25mm and not less than

2. The grating according to claim 1 wherein the grating is cast iron and each bar is T-shaped in transverse profile having a flange and web, the web being tapered and having a median width approximately half the width of the flange.

3. The grating according to claim 1 or claim 2 wherein the grating has a single cross-bar positioned about halfway along the grating, thereby separating the grating into two spaced sets of slots and bars.

4, The grating according to any one of the preceding claims wherein the :cross-bar has an upper surface which is contiguous with the upper surface of the grating or is recessed below the upper surface of the grating.

5. The grating according to any one of the preceding claims wherein the i grating is positioned in a frame just below the grade level of a roadway so that the grating with its closely spaced bars give the appearance of blending into the roadway.

6. The grating according to any one of the preceding claims wherein the bars and slots range in relative width with the bars and slots being about the same L~ width, the bars being slightly wider than the slots.

7. The grating according to any one of claims 1 to 6 wherein the bars and slots are all the same size and uniformly distributed over the surface of the grating.

8. The grating according to claim 6 or claim 7 wherein the slots have a tyre penetration depth into a slot of a maximum of 5mm where a 25mm cross- sectional diameter tyre is at 400kPa inflation on a 686mm diameter wheel under a 50kg load and positioned vertically over a slot.

9. The grating according to any one of the claims 1 to 6 or claim 8 wherein the bars and slots are evenly distributed. The grating according to any one of claims 1 to 9 wherein slot widths range from 15mm to S. 11. The grating according to any one of the preceding claims wherein the *o grating is manufactured using a mould made of two mould portions, the flange section of the bars being moulded in one mould portion while the web is moulded in the other mould portion so that surface finish on the upper surface of the grating is optimised. •oo 12. A grating substantially as described with reference to the drawings. S. DATED this 20th day of May, 1994. '1 PHILIP GRAHAM BK.TJNE By his Patent Attorneys INTELLPRO l-r I ABSTRACT A grating 10 suitable for use adjacent a curb or raised median (not shown) of a roadway (not shown) to intercept water flowing along the roadway, the grating has an upper surface 11 defined by a plurality of narrow interdigitated closely spaced slots 12 and bars 13 where in this case, the slots and bars are about the same width. In use, the grating is arranged so that the slots and bars 12 and 13 are positioned in the direction of water flow along the grating to improve hydraulic efficiency. In the illustrated embodiment, the slot width is 17mm whereas the bar width is 21 mm. As most bicycle tyres are 20mm to 25mm in width, the 17mm wide slots provides for less than a 5mm penetration of a tyre into the slots. Under these circumstances, the use of this particular grating in a roadway is for all practical purposes imperceptible to a cyclist riding over the grating. S* a a.