Solutions to ease the pressure of thousands of new homes on Arun’s infrastructure are yet to be finalised.
The district council has instructed consultants to explore the improvements needed to ensure the area copes with expansion.
More than £266million of works have been identified, including tackling ‘severe’ congestion at 15 junctions and a new secondary school.
But precise solutions for dealing with the likes of healthcare, wastewater and more facilities for emergency services have yet to be identified.
On wastewater, a report by consultants Hampshire County Council read: “At this time, Southern Water is unable to determine a final strategic approach to dealing with the increased waste water as a result of strategic site development.”
The infrastructure improvements are being explored as part of work on the council’s local plan.
The council has commissioned a series of studies to see if it can meet its government-set target of identifying land for 845 homes per year up until 2031.
A transport study by Systra highlighted 15 junctions across the district which would need work to mitigate a ‘severe’ increase in traffic.
These include the busy Oystercatcher and Comet Corner junctions, which have been subject to numerous calls for action by residents in recent years.
The report estimates housebuilding could increase traffic by 168 per cent at the Ford level crossing.
Hampshire County Council estimated roadworks could cost in excess of £2.5million – not including a potential A29 bypass.
Contributions from developers would be sought to carry out improvements.
Councillor Ricky Bower, cabinet member for planning and infrastructure, said proposals were indicative and precise details would come forward through individual planning applications.
But Littlehampton town councillor Derrick Chester said lack of planning over wastewater had led to delays in delivery of the North Littlehampton development.
He claimed plans should be formalised in advance for all key infrastructure.
Mr Bower said: “I am not concerned about the ‘lack of certainty in finding a solution’ to wastewater issues at this time – that will come when any planning application is submitted.
“There are other solutions to wastewater than those provided by Southern Water.”
Mr Bower said he had asked the Coastal West Sussex Clinical Commissioning Group to provide a plan within four months to address the issue of healthcare – another area where precise solutions were yet to be refined.