As in any wise college or educational savings plan, it makes good dollars and sense to start early, to contribute to the fund steadily and use time to help grow the needed money pot. That same concept should apply to the certain need for public schools that will be growing along the urban core of the rail transit route.

So the state Board of Education — sooner rather than later — needs to make the tough decision to impose a schools impact fee on home builders along the route’s four miles between Kalihi and Ala Moana.

The Department of Education estimates that 10,000 students would be enrolling in urban Honolulu schools as developments pop up along the rail line. For months now, it has asked its Board of Education to adopt a policy that would apply a schools impact fee on developers along that route.

The original proposal called for charging builders of new homes $9,374 per unit to help pay for new schools in the area. That was nixed in November by BOE members, citing concerns about hindering affordable housing development. It was a valid concern then — but one that should be allayed via successful passage of a measure this legislative session to exempt affordable units from the fees.

DOE officials returned to the BOE’s Finance Committee last week with a revised fee of $5,858 per unit: over the next 20-30 years, that lowered impact fee could collect an estimated $228 million to help pay for new schools, compared with the original $365 million from the higher fee. But this new proposal, too, got blocked for up to 90 days — this time, by two new obstacles cited by BOE members.

Constitutionality over a blanket policy was questioned — so now, the state attorney general is urged to suggest a legally sound way to impose an impact fee, perhaps on a project-by-project basis, based on school-students proportionate demand around a defined area.

It bears noting that a 2007 state law already authorizes the DOE to collect fees from developers in high-growth areas to offset the building of new schools. Already, for instance, a BOE-approved school impact fee district in Leeward Oahu has collected about $800,000, and on Maui, some $2 million.

Also questioned: Whether the DOE, instead of depending on impact fees, has moved apace to revenue-enhance its lands via Act 155, the 2013 state law that gave it five years and $650,000 to establish a pilot program to scope unused or underused portions of school lands for public uses such as workforce housing.

Indeed, the DOE needs to optimize this path; it’s taken more than three years and nearly half-million dollars so far to identify three sites for this purpose. One, at 1042 Young St. now housing two DOE branches, seems to be a nonstarter since the city landowner doesn’t support the DOE’s proposed mixed-use development. The other two hold promise: the 690 Pohukaina site in Kakaako, eyed for years for a school and mixed-use development; and a 22nd Avenue site for “market rentals” that would fill the needs of both rental housing and DOE revenue generation.

The BOE should be setting the tone of expectations for developers along the high-growth urban stretch of rail. It is not Act 155 or school impact fees; it should be Act 155 and impact fees, and other innovative strategies that make sense. Let’s hope the BOE’s hedging doesn’t mean a lack of will to call on developers and others who stand to benefit to be integral parts of the solution.

A DOE analysis projects that residential development in the Kalihi-to-Ala Moana area is expected to add some 39,000 new housing units, with about one-fifth to be affordable or low-income housing. The 13 schools now serving the area can handle only up to 1,750 more students, and the DOE expects the growth to demand up to six new elementary schools and 1.5 middle and 1.5 high schools, costing $750 million total.

That demand won’t go away.

Vibrant new communities of residents will necessitate vibrant schools; growing families know good schools are a selling point, so developers benefit from school-fee investment. All sectors have crucial roles to play in how Hawaii gets shaped for the next generations. That will entail affordable housing for our residents, which necessarily means well-realized foundations such as quality public schools providing opportunities. All who profit must be willing to pay in.