In addition to a suitable quantity of feedstock, the price spread between the value of alkylate product and alternate feedstock disposition value must be large enough to justify the installation.
These components are the amount of volume affecting the price, the price spread or range of the price (not the bid/ask spread), and where price closes.
Traders have said the rapid expansion of oil shipments by train has been a big factor in easing the constraints and tightening that price spread since then.