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Traffic Assessment Proposed Extension of Gravel Extraction at Gravel Pit Road, Nook SUBMITTED BY: TERRY EATON Traffic Engineer 29 Carey’s Road Bridgenorth Tas 7277 TEL/FAX: (03) 6330 1510 TE:SZ:YD SETPEMBER 2008
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Page 1: TA - Gravel Pit Rd, Nook - EPA Tasmaniaepa.tas.gov.au/documents/riley_quarry_products_rileys_gravel_pit... · Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel

Traffic Assessment

Proposed Extension of Gravel Extraction

at Gravel Pit Road, Nook

S U B M I T T E D B Y :

T E R R Y E A T O N

T r a f f i c E n g i n e e r

2 9 C a r e y ’ s R o a d

B r i d g e n o r t h T a s 7 2 7 7

T E L / F A X : ( 0 3 ) 6 3 3 0 1 5 1 0

TE:SZ:YD

S E T P E M B E R 2 0 0 8

Page 2: TA - Gravel Pit Rd, Nook - EPA Tasmaniaepa.tas.gov.au/documents/riley_quarry_products_rileys_gravel_pit... · Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel

Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 2

By Terry Eaton

C O N T E N T S

Page

1. INTRODUCTION..........................................................3

2. THE SITE.....................................................................3

3. THE PROPOSAL .........................................................4

4. ROAD FACILITIES.......................................................4

5. TRAFFIC DATA ...........................................................7

6. ASSESSMENT.............................................................8

7. CONCLUSION ...........................................................10

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Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 3

By Terry Eaton

1. Introduction

This report is provided as an assessment of the traffic impact for the

extension of the existing gravel extraction activity at AG & BJ Riley’s

quarry, Gravel Pit Road, Nook.

Preparation of this report has included a site visit and discussion with

the quarry operator.

2. The Site

The site is the existing gravel pit located off the end of Gravel Pit Road

some 1.5 kilometres from the Nook Road junction. Indications are that

the public section of Gravel Pit Road extends some 900 metres from

Nook Road with the remaining distance to the pit as a private gravel

access road.

The present quarry activities are based on contractor demand for

materials with the site operation to win, sieve and stockpile materials

ready for cartage, 4 employees are normally engaged in this process.

Cartage is generally batched with cartage at some 2,000 tonnes per

week with average orders of some 4,000 tonnes, i.e. cartage over 2

week periods.

Land uses in proximity are generally rural with the quarry in a forested

area with abutting rural land in use for grazing with a major sheep

export holding area on the south side near the gateway to the Quarry.

The loading facilities at the sheep holding pens are set back from

Grave Pit Road such that truck manoeuvring at this site is away from

the Gravel Pit Road carriageway. Closer to Nook Road is a Boral

Quarry site with activities on both sides of Gravel Pit Road with the

road crossing controlled by “Give Way” signs to maintain priority on

Gravel Pit Road. It is understood that the cartage from this site is

similar to the AG & BJ Riley demand of some 2,000 tonnes per week.

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Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 4

By Terry Eaton

3. The Proposal

The proposal is to extend the present quarry activities for another 15 to

20 years with production to some 50,000 to 60,000 tonnes/annum.

Indications are the quarry activity will generally be as per the existing

rate with the present employees and cartage up to some 2,000 tonne

per week.

4. Road Facilities

•••• Gravel Pit Road

This road could be classified as a dead-end local rural access

road serving local agriculture needs and the quarry activities.

The road is constructed for its public length of some 900 metres

with a minimum width of some 4.5 metres with widening up to

some 6.5 metres at corners and crests with formed shoulders and

grass verges. Some 100 metres from Nook Road there is a short

narrow section due to a road edge failure at a culvert.

Generally, the road standard could be considered adequate for

use by heavy cartage vehicles, particularly as there is no external

through traffic using the road with almost all use seen as relating

to the roadside commercial activities.

Washed out area

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Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 5

By Terry Eaton

The road profile is undulating and as a downgrade to Nook Road.

The alignment is generally as two straight sections joined by a

tight curve (some 80 metres radius) at the Boral site.

The road standard is seen as limiting travel speed to some 55 to

65 km/h.

Traffic accident information indicates no reported accidents on

this road for the last 5 years.

•••• Nook Road

This road provides a rural collector link between Sheffield Main

Road at Acacia Hills via Nook to Sheffield.

The road could be considered as a Category V road within the

Kentish Planning Scheme’s Road and Rail Asset Code, with the

primary purpose to provide access to rural properties with a

significant through traffic component.

The road is constructed with a sealed pavement some 6.0 metres

wide, gravel shoulders some 1.0 metres wide, side swale drains

and grass verges. Additional pavement width is provided at tight

curves to accommodate the swept path of semi-trailers.

The road alignment is a series of straights and relatively tight

curves with steep hill sections either side of the ridge at Gravel

Pit Road. The road between Gravel Pit Road and Sheffield Road

is considered of a high standard for the use and the terrain.

Hill section

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Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 6

By Terry Eaton

The road standard is seen as limiting travel speed to some 70 to

75 km/h in proximity to Gravel Pit Road.

Accident records indicate 10 accidents for the 3.3 kilometre

section from Sheffield Main Road to Gravel Pit Road for the last 5

years. The link accidents included 1 serious accident, 4 minor

accidents and 3 property damage with 2 serious accidents

recorded for the Sheffield Main Road/Nook Road junction.

•••• Nook Road/Gravel Pit Road Junction

This junction is near a crest on Nook Road and is constructed

with a short section of seal on the Gravel Pit Road approach.

A minor forest access road is located opposite Gravel Pit Road.

The throat length at the edge of the through carriageway is

widened to some 120 metres, with some 80 metres on the

approach and 40 metres on the departure to/from the centreline of

Gravel Pit Road the additional areas provide for left turn

approach/departure tapers.

The gradient on Nook Road past the junction is an upgrade from

North to South of some 4% with a downgrade of some 8% north

of the junction.

Sight distance at the Gravel Pit Road junction is some 175 metres

to the north and some 165 metres to the south. The sight distance

to the north does rely on maintaining tree/shrub clearance within

the site triangle.

Traffic accident information indicates no accidents at this junction

in the last 5 years.

View to south View to north

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Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 7

By Terry Eaton

5. Traffic Data

•••• Nook Road

Traffic information indicates a volume of some 900 vehicles per

day on Nook Road near Sheffield Road. Allowance for traffic

growth at some 2% per annum suggests a year 2028 value of

some 1,550 vehicles per day. For assessment the peak hours

are provided for at 12% of the ADT with 70/30 split with the major

value for traffic toward Sheffield Road for the morning and the

reverse for the evening.

•••• Gravel Pit Road

Light vehicle use on this road relates to the commercial activities

and is likely to be less than 40 vehicles per day. For the

commercial uses the following estimates are provided:

Annual

No. Loaded Trips

Estimated Peak Day Volume

(two-way)

Gravel Pit (Riley)

60,000 tonne

2,400 40

Fine Crushed Rock (Boral)

60,000 tonne

2,400 40

Sheep transport

60,000 300 * 80

Total 5,100 160

* volume in/out of holding area

Addition of the peak day heavy and light vehicles suggests a peak

ADT of some 200 vehicles with some 80% as heavy vehicles.

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Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 8

By Terry Eaton

6. Assessment

6.1 Road Safety

•••• Nook Road

The assessment is that this road is satisfactory to cater for

the cartage of materials from Gravel Pit Road.

An assessment of the accident history based on the Traffic

Authority of New South Wales’ average accident rate for

main rural roads of 0.49 accidents per million vehicle

kilometres of travel indicates a critical accident rate of 1.48

accidents per million vehicle kilometres for the section from

Gravel Pit Road to Sheffield Road. The actual rate of 1.33

accidents per million vehicle kilometres is less than this

critical value indicating an acceptable level of safety safe .

•••• Gravel Pit Road

In view of the use of this road by traffic generally local to the

conditions with no through traffic the road standard is

considered satisfactory provided the surface is maintained

and any emerging road hazards are addressed. With regard

to hazard the site visit found a short section of road near the

Nook Road junction where a culvert wash out has reduced

the road width at a low point (sag curve). The road is on an

embankment with the risk of further edge failure. Remedial

measures such as extension of the culvert, pavement

widening and consideration for installation of edge protection

are considered prudent improvements.

•••• Nook Road/Gravel Pit Road Junction

The available sight distance at this junction, minimum value

165 metres to the south, meets DIER requirements for an

approach speed of some 75km/h. The available sight

distances also meets truck stopping distance for approach

speeds of some 75km/h for the approach from the south and

some 100km/h for the approach from the north. Truck

stopping distance is considered the minimum standard to be

met with the available sight distance to the south considered

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Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 9

By Terry Eaton

consistent with the speed environment for the location. The

sight distance to the north is well in excess of truck stopping

distance due to the steep gradient.

Consideration could be given to the following measures:

(i) Maintain the sight triangle to the north by

keeping the area clear of shrubs and trees.

(ii) Installation of a W5-22 (B size) truck

warning sign with attached “Turning Traffic”

plate some 100 metres prior to Gravel Pit

Road for both approaches. These signs will

increase awareness of the truck

movements.

6.2 Traffic Service

•••• Nook Road/Gravel Pit Road Junction

The predicted peak hour traffic volumes indicate a high level

of service will be available for vehicles exiting Gravel Pit

Road with the practical absorption capacity for right turns

from Gravel Pit Road at some 400 vehicles per hour (gap

time 8 seconds and 5 second move up time – typical for

truck movements).

75

125

5

15

2028 Evening Peak Hour

Gravel Pit Road

Nook Road

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Traffic Assessment – Prosed Extension of Gravel Extraction at Gravel Pit Road, Nook 10

By Terry Eaton

Comparison between the actual predicted turn volume of

15 vehicles and the practical absorption value of

400 vehicles is indicative that a high level of service will be

available.

•••• Nook Road

The predicted peak hour flow of some 200 vehicles per hour

suggests a nominal level of service “C” value for Nook Road

with a lower service level for the hill section. However, the

use of Nook Road by heavy vehicles is seen as consistent

with the road classification as a rural collector.

•••• Gravel Pit Road

The road standard with remedial repair work at the culvert

near Nook Road is considered satisfactory for the predicted

traffic volume of up to 200 vehicles per day.

The gravel surface is considered adequate particularly as the

use is generally by heavy vehicles and as there are no

residences close to the roadway, i.e. no dust nuisance issues.

7. Conclusion

A traffic assessment for extension of the AG & BJ Riley’s Gravel Pit

operations at Gravel Pit Road, Nook, indicates no significant traffic

safety or traffic service issues provided some road repairs including

pavement widening with consideration for edge protection at the

culvert on Gravel Pit Road near Nook Road are advanced. It is also

considered prudent to keep the sight triangle to the north of the Nook

Rd / Gravel Pit Rd. junction clear and install “Truck Entering” warning

signs on Nook Road either side of this junction.

Terry Eaton


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