How to plan precast production for a large infrastructure project
The most common planning mistake we see is starting from the factory's capacity. Start from the other end: how fast can your gangs lay, and when do they need material in each zone?
Most production plans are written from the supplier's point of view: we can make so many per day, so it will take so many weeks. That is backwards. Nobody on site cares how fast the press runs. They care whether material is waiting for them when a zone is ready.
Step 1: start from the laying programme
Take the project programme and work out, zone by zone, how much material the laying gangs will need and when. Pavers in the container yard from this month, kerbs for the roads from that month, tiles following the cable trenches as they are backfilled. That demand curve is what production has to match.
Step 2: work back through curing
A block made today cannot be laid today. It needs curing time before it reaches strength and passes its tests. So production has to run ahead of laying by at least the curing period, plus a buffer of finished stock so a bad day at the press does not stop the work front.
Step 3: size the daily output
Now you know the peak daily demand and the lead time, and you can size the plant. Big numbers become easier to reason about when you break them down to a day. At Dhamra Port the scope was 2,50,000 square metres of pavers; divide that by the working days the programme allows, knock off the days the monsoon will take from you, and you have the real daily target. That one number decides how many machines, shifts and people the site needs.
Step 4: settle the mix and the moulds early
Mix designs need the project's approval before production starts, and they depend on the actual sand and aggregates available at that site. Trial batches and cube results take time; build that time into the start of the programme, not the middle.
Mould choice matters too. Steel moulds on a vibro hydraulic press suit high-volume pavers, kerbs and blocks. Rubber moulds with the wet-cast process suit products like chequered tiles, and also give design flexibility. Decide this per product, early, because moulds have their own lead times.
Step 5: agree the QC plan before the first block
At Dhamra Port, production for 2,50,000 square metres of M-50 pavers ran under a QC plan agreed with the client before regular production began. Agreeing the plan up front, what gets tested, how often, and what happens to a failed batch, saves weeks of argument later. Leave it vague and you will be negotiating it in the middle of the job, which is the worst time to do it.
Step 6: plan supply by zone
On long linear works, material should arrive where it is needed, when it is needed. At Amaravathi, tiles were stacked zone-wise and moved to each stretch as the ducts were ready to be covered. A stack of tiles sitting beside an open trench for weeks is an obstruction, not progress.
Step 7: plan for the weather
Monsoon affects curing, stacking yards and laying all at once. Plan buffer stock before the rains, protect curing areas, and make sure the yard drains.
Step 8: decide who lays
If the same organisation makes and lays the product, planning gets simpler because there is one programme, not two. It also puts responsibility for the finished pavement in one place, which we think is where it belongs.