The projected costs to complete Honolulu’s 20-mile rail transit system have grown by about $70 million in the past four months, based on the local rail agency’s ongoing analyses of risks to the project.

In August, the Honolulu Authority for Rapid Transportation risk manager Paul Johnson told agency board members there was an 80% probability that rail construction costs would not exceed $8.14 billion.

This week, a HART spokesman confirmed that the agency’s 80% probability cost estimate has risen, now up to $8.21 billion.

The updated figure was not shared Thursday with HART’s Project Oversight Committee members, however.

Instead, for his latest briefing on risks, Johnson switched to a less conservative cost estimate, based on 65% probability. That amount — $8.136 billion — happens to resemble the earlier, more conservative cost he shared back in August.

In a recent report, HART says it switched from reporting its 80% estimate down to 65% in order to follow the Federal Transit Administration’s standards.

That switch, however, has helped to mask HART’s own assessment that future risks are already driving up the projected costs. Johnson’s report flags more than 180 such risks facing rail, and his cost projections assume that HART will proactively address them.

Despite that assumption, his briefings have nonetheless added tens of millions of dollars in estimated cost in recent months, as the mega-project approaches yet another critical juncture in its difficult history.

Still, HART is holding firm to its longtime official construction budget of $8.165 billion, and its overall budget of just over $9 billion, which includes the financing costs.

“That number is based on actual field info and measurements,” HART spokesman Bill Brennan said in an email.

The FTA, meanwhile, thinks the overall cost will be closer to $9.14 billion.

A Moving Target

The range of numbers shows how much of a moving target rail’s final cost actually is. Some longtime critics maintain the price tag could soar well past $9 billion.

Utility relocation along the crowded Dillingham Boulevard corridor is far behind schedule. HART is scrambling to complete a traffic management plan that will allow that $400 million in utility work and subsequent rail line work to occur as swiftly as possible, while causing as few headaches to Kalihi-area businesses and residents as possible.

Three months ago, Honolulu Mayor Kirk Caldwell implored the rail agency’s board to “make sure you’re on HART’s ass” to get that plan done. It’s not expected to be finished until next year, however.

Rail and city officials expect to open bids next year on a proposed public-private partnership to complete rail’s last 4 miles and eight stations into town.

Previously, they had hoped to open those bids this month. Now, as bidders have signaled they need more time, the city hopes to get those bids by the middle of next year, according to HART Executive Director Andy Robbins.

On Thursday, Johnson flagged right-of-way for the transit line, underground conditions for utilities, and potential added costs with rail’s communications and systems designer, Hitachi Rail, as the top risks currently facing the project.

Another key risk he pointed out was the chance that the bids to finish rail come in higher than what HART has budgeted. There’s not much contingency available should that happen, he told board members. Robbins has stated separately, however, that the bidders are aware of what the city can afford.

Johnson further reported that HART’s risk analysis has the transit line completed in February 2026 — two months behind the agency’s goal to finish by December 2025.

FTA estimates the project will be done by September 2026.