McCullys Gap battery’s traffic study models four other developments expected to use Sandy Creek Road, not the neighbouring Bells Mountain and Gelston batteries; submissions close 13 October

If you live on or drive Sandy Creek Road, east of the New England Highway at Muswellbrook, the McCullys Gap Battery Energy Storage System is the project on public exhibition now, and the window closes on Tuesday 13 October 2026. The Department of Planning, Housing and Infrastructure’s exhibition notice says the application and environmental impact statement are on exhibition from 15 September until 13 October, and that a submission must be lodged online through the NSW Planning Portal before the close of exhibition. Anyone can make one.

We read the EIS (August 2026, prepared by GHD for the applicant), its traffic and transport report and the council’s written input, and checked the neighbouring battery, pumped hydro and thermal projects on the NSW Major Projects register this morning. The useful thing for a submission is what the traffic report counts, and what it leaves for later.

What is proposed

The applicant is Muswellbrook Pro Unit Holdings Pty Ltd; the EIS’s list of abbreviations gives BW Group (parent company of the applicant). The battery would sit across 380 and 578 Sandy Creek Road, about six kilometres northeast of Muswellbrook, and connect by an 800 metre line to the existing Muswellbrook 330 kV substation. The EIS says that, Subject to receiving planning approval, the project is expected to be operational in 2029 and operate for at least 30 years (p. vii).

The McCullys Gap battery, as the EIS describes it

Application SSD-81555720, on exhibition 15 September to 13 October 2026.

• Size400 MW for four hours: 1,600 MWh
• Where380 and 578 Sandy Creek Road, McCullys Gap, Muswellbrook Shire
• Connection800 m line to the existing Muswellbrook 330 kV substation
• BuildAbout 18 months; a peak of around 150 workers for four to six months
• RunningRemotely operated; up to six personnel for maintenance on a quarterly basis
• ClearingUp to 16.92 ha of native vegetation, including up to 3.66 ha of a Commonwealth-listed critically endangered ecological community; a controlled action under the EPBC Act
• For the community$200/MWh a year, which the EIS puts at about $320,000 a year, CPI-indexed, through a planning agreement with the council
• ExpectedOperational in 2029, subject to approval

Who else is using Sandy Creek Road

The traffic report’s cumulative section lists eight approved and proposed projects in the vicinity of Sandy Creek Road that could overlap with this one’s construction (p. 48). Its numbers come from four of them. The report says Four developments have been identified as potentially relevant to assessing future traffic conditions in 2028, that All four developments are expected to access or egress their sites via Sandy Creek Road, and that their published traffic assessments were used to inform the cumulative traffic modelling (p. 9). The four are the Muswellbrook Solar Farm, the approved Muswellbrook battery, the Muswellbrook Bypass and the Queensland Hunter Gas Pipeline.

The other four are all still preparing their EISs. Of those, the report says A number of the developments currently at ‘Preparing EIS’ stage, do not have sufficient available inputs (e.g., peak hour construction volumes, confirmed access routes, or sequenced programs) to support inclusion in this assessment (p. 49). Two of them are the biggest batteries on the road.

Eight projects the traffic report lists around Sandy Creek Road, and which four it modelled

Status and size from each project’s NSW Major Projects register page, read 10 October 2026. Location and planned start are the traffic report’s (Table 7.1), which says it took them from the register. The tags are our reading of the report’s section 2.4.

• Bells Mountain battery
  Not modelled RegisterPrepare EIS. Construction of a 750 MW / 1,500 MW-hour battery and associated infrastructure; 388 and 408 Sandy Creek Road (SSD-83968208). Traffic reportImmediately southwest, connecting into the Muswellbrook 330 kV substation; planned start 2027 to 2028.
• Gelston battery
  Not modelled RegisterPrepare EIS. A battery with a capacity of approximately 400 MW/1600 MWh; Sandy Creek Road / Gelston Lane (SSD-104190458). Traffic reportImmediately southwest, connecting into the 330 kV substation; planned start 2027 to 2028.
• Muswellbrook Pumped Hydro
  Not modelled RegisterPrepare EIS. A 500 megawatt pumped hydro power station, declared critical state significant infrastructure (SSI-76014961). Traffic reportImmediately south; planned start 2026; the report says its traffic figures are not yet available.
• Muswellbrook Thermal Storage
  Not modelled RegisterPrepare EIS. Up to 30 MW thermal, 4.99 MW electrical; Sandy Creek Road (SSD-88560713). Traffic report2.2 km southwest; planned start unknown.
• Muswellbrook battery
  Modelled RegisterDetermination; a 150 MW / 300 MWh battery energy storage facility at 20-24 Sandy Creek Road (SSD-29704663); a modification is in assessment. Traffic report3.9 km southwest; construction expected from Q4 2026, 12 months.
• Muswellbrook Solar Farm
  Modelled RegisterDetermination (SSD-46543209); being built in stages (our 8 October report). Traffic report800 m south; construction from 2026.
• Muswellbrook Bypass
  Modelled RegisterNot checked; the EIS lists it as approved under Division 5.1 of the planning act. Traffic report4 km southwest; planned start 2027.
• Queensland Hunter Gas Pipeline
  Modelled RegisterDetermination (MP06_0286), a 2009 approval per the EIS. Traffic reportImmediately east; planned start unknown.

The report’s reason for still finding no problem is the road’s spare capacity. Even for the unmodelled projects, it says, significant cumulative impacts are not expected because the road network, particularly Sandy Creek Road and the New England Highway (A15)/Sandy Creek Road intersection already demonstrates substantial remaining capacity, and the projects without data are expected to generate comparatively low and intermittent construction traffic along Sandy Creek Road (p. 49). The EIS carries the conclusion forward: When considering relevant future projects with available information online, significant cumulative traffic impacts to the local road network during construction are not anticipated (p. 102).

The two documents also disagree on timing. The traffic report’s table gives Bells Mountain and Gelston planned starts of 2027 to 2028. The EIS’s own cumulative screening table says construction timing for both is not yet available (Table 20.2, pp. 151 to 152), and adds that there is limited public information available regarding the Bells Mountain and Gelston BESS projects at the time of writing (p. 154).

The turn-off and the level crossing

Sandy Creek Road crosses the Main Northern Line about 45 metres east of the highway. The traffic report counts about 53 to 59 trains a day over the crossing and notes a potential risk for construction vehicles to queue back onto the New England Highway (A15) (p. 40). Today, the EIS says, Sandy Creek Road carries around 38 vehicles in each of the morning and afternoon peaks (p. 101). At its own construction peak, the battery would add up to about 78 vehicle trips in each peak hour, 64 of them inbound in the morning (Table 13.1, p. 102). With the four modelled projects, the report’s summary puts the total at approximately 355 vehicle trips during the construction peak hour at the highway intersection (p. ii).

The report then modelled the intersection with the crossing shut for three trains an hour, 3 minutes 43 seconds each, in 2028 (pp. 40 to 42):

Modelled morning-peak queue on the highway’s southern approach while trains close the crossing, 2028

95th percentile queue in metres. Bars to scale; the full width is 300 m. Both scenarios include the four modelled developments; neither includes Bells Mountain or Gelston.

Without the McCullys Gap battery186 m

186

With it266 m

186 +80

Right-turn lane storage, south of Sandy Creek Roadabout 60 m

60

To manage it, the report suggests the contractor get rail timetables from the Australian Rail Track Corporation, schedule heavy vehicles where practicable, consider traffic controllers on the highway during closures, and tell drivers not to queue across the crossing (p. 42). As at 10 October we did not find those queue measures in the EIS’s consolidated mitigation table (Appendix C), whose traffic measures commit to a construction traffic management plan prepared with the council, Transport for NSW and the rail corporation as relevant; nor do the queue lengths appear in the EIS’s traffic chapter, which we searched for them.

What the community would get

In April 2025, council staff sent the department their input on what the EIS should cover. The letter sets out what the council resolved in February 2025 for battery projects: A monetary contribution of $200/MWh consistent with the planning agreements with other BESS projects, plus a set of local commitments (p. 2). The EIS adopts the rate. 1,600 MWh at $200 is $320,000, our arithmetic, which matches the EIS’s approximately $320,000 per annum (adjusted) (p. 133). The rest of the list is a different picture.

What Muswellbrook asked of battery projects, against what this EIS proposes

Council asks from its letter of 15 April 2025, items 2 and 16; EIS commitments from the main volume, Appendix C and Technical Reports 7 and 11. The tags are our reading.

• Annual payment
  As asked Council asked$200/MWh of installed capacity, every year of operation, indexed to CPI. EIS proposes$200/MWh, about $320,000 a year, CPI-adjusted, through a planning agreement (p. 133).
• How it is spent
  Later Council asked10% to council specialist staff, 90% to the Muswellbrook Shire Community Benefit Fund. EIS proposesThrough the Community Benefit Fund; allocation, eligibility and administration will be finalised through the planning agreement process (p. 19).
• Near neighbours
  Not found Council askedNeighbourhood benefits as rate rebates for property owners in the direct vicinity. EIS proposesNo rate rebate commitment found in the documents we searched.
• Apprentices
  Not found Council askedAt least four shire residents as apprentices or trainees during construction. EIS proposesNo apprentice or trainee number found in the documents we searched.
• Local spending
  Partly Council askedA procurement plan with a minimum 5% local target by project value. EIS proposesInformation for local suppliers and a procurement contact on the project website; no target (measure SE2, p. 134).
• Road wear
  Later Council askedPavement damage on Sandy Creek Road accurately calculated per project, part-funded through the planning agreement (resolution of 14 May 2024, p. 5). EIS proposesRoad condition surveys before and after, with repairs (T5); contribution arrangements will be confirmed and finalised following project approval (Technical Report 7, p. 49).

On worker housing, which the council also raised, the EIS says The project has committed to avoidance of the private rental market and that a workforce accommodation strategy would be prepared with the council before construction (p. xi).

Our read

This section is opinion, based on the facts and documents above.

The money is the settled part. The applicant has matched the council’s battery rate. What is left open is everything else on the council’s list, and the place those things get decided is the planning agreement, after approval. A submission that wants rate rebates for neighbours or apprentices written in should ask for them now, as conditions.

The traffic case rests on a judgement where a number is missing. The report modelled the two batteries it had data for and treats the two it did not as comparatively low in traffic. The one battery it did model, at 150 MW, was put at 51 vehicle movements during the morning and afternoon peak hours by its own traffic assessment, as the report relays it (p. 11). Bells Mountain, at 750 MW, is five times that size, and the report lists it with a planned start of 2027 to 2028, overlapping the 2028 peak it assumes for this one. We cannot say what its traffic will be, and neither can the report. That is the point: with the modelled highway queue already past the right-turn lane before this battery is added, the reasonable ask is that the department see a cumulative model with Bells Mountain and Gelston in it before any of them is determined.

How to have your say

Submissions go through the project’s register page (“Make a submission”) and need a Planning Portal account, your name and address, whether you support, object or comment, your reasons, and a declaration of reportable political donations, according to the notice. Submissions are published; you can ask for your name to be withheld. The portal’s customer support line is 1300 305 695. The department’s contact for the project is on the register page.

One more Upper Hunter energy project is on exhibition this week: Bowmans Creek Wind Farm Stage 2, a wind farm with up to 21 wind turbines, until 12 October.