The state Department of Transportation (DOT) needs to explain the abrupt U-turn it made in deciding to ditch long-awaited highway construction projects under its “Capacity Program” and focus instead on maintaining existing roadways.

Citing the lack of a steady revenue stream, DOT Highways Division Deputy Director Ed Sniffen said he could not justify adding new roads if the department can’t sustain the current system. And while that might turn out to be a reasonable route, DOT’s announcement rightly shocked many legislators, who approved an infusion of $37 million to the DOT budget in the just-ended session.

The deferral of major highway projects was certainly news to motorists, many of whom have waited years for expansions and improvements to relieve congestion in areas including Puna and Kaneohe.

While DOT insists it presented this information numerous times during testimony before legislative committees and at public meetings, there was a palpable sense of surprise among even lawmakers.

One legislator went so far as to describe the department’s new direction as “blackmail.” Rep. Joy San Buenaventura, who represents Puna residents, said: “This is extortion, I don’t see it any other way. … They’ve never talked about this huge disparity before until now, and I think this is payback.”

When Gov. David Ige’s administration pushed for an increase in the state’s gas tax, registration fee and weight tax this past session, there was little warning to the public that major highway construction projects would fall by the wayside if the increases weren’t approved. Ige’s proposals would have generated an extra $70 million a year for highway improvements.

Among the projects now deferred is one to enlarge Highway 130 on Hawaii island between Pahoa and Keaau. That project is not a luxury, but a necessity for safety since some 30,000 people rely on that roadway, which bottlenecks to one lane in each direction.

It’s disturbing that, according to San Buenaventura, the DOT implied in a discussion that if she didn’t vote in favor of the tax and fee increases, the Highway 130 project would be deferred.

Even more troubling is the department’s feeble attempt to inform the public of the ramifications if the DOT measures failed.

Other projects in peril include the $251 million H-1 Freeway eastbound widening from Waiawa to Halawa, and the $66 million Kahekili Highway widening from Haiku Road to Kamehameha Highway. Kauai’s $583 million Kuhio Highway improvements from Hanama- ulu to Kapaa and portions of Maui’s $234 million Honoapi-ilani Highway realignment, or Lahaina Bypass, also are on the deferred list.

Sniffen explained that the state must commit about 90 percent of the Highway Division’s annual $300 million to system preservation and safety improvements, leaving only 10 percent, or $30 million, for projects that would increase capacity. That renders the Capacity Program of proposed expansions nonexistent, Sniffen said — a troubling situation since that information was not fully presented to the public before the Legislature wrapped up in May.

DOT officials have rightly come under fire in recent years for taking far too long to spend down its federal highway dollars. DOT’s poor management of those funds forced the Federal Highway Administration in 2014 to warn the state that unless it spent the money more quickly, it would lose federal highway funds.

Six years ago the state had $940 million in unspent federal highway dollars, but DOT brought that figure down to $540 million by the end of May. While that’s progress, the state’s inability to take full advantage of those funds and expand the roadway system in areas that desperately need relief is a disappointment.

It is frustrating that the state now finds itself at this juncture — with hundreds of millions of dollars of projects in limbo, some of which could be delayed for decades.

House Finance Chairwoman Sylvia Luke is skeptical of DOT’s reasons for deferring such a long list of projects, especially with additional $37 million alloted.

“It’s kind of troubling and puzzling that DOT is now pointing to the failure of the tax bill … to delay the projects,” Luke said. “That cannot be right. There has to be another reason.”

It’s yet unclear whether DOT is holding these projects hostage to strengthen its position heading into next session, when the Ige administration is expected to reintroduce the tax- increase measures. What is clear is that the public would benefit from promised road relief, as well as more straightforward information from its DOT.