Baton Rouge traffic engineers are hurtling forward with plans to build a Pecue Lane and Interstate 10 interchange, which must start construction by spring 2017 or else the report on which the project hinges will expire.

Green Light Plan Program Manager Jonathan Charbonnet told a meeting of mostly local officials Tuesday that making up for a $36 million funding shortfall to build the interchange is the most difficult challenge ahead. They have about a year-and-a-half to find the extra dollars to build the interchange.

Everything else is moving quickly. The Federal Highway Administration is expected to authorize Charbonnet this week to hold a final public hearing on the interchange. From there, it’s mostly a matter of receiving the appropriate permits and more federal clearances to start construction by the deadline.

The preferred design for the interchange is a diverging diamond, which would be the first of its kind in Louisiana but is common in many other states. When driving a diverging diamond, traffic briefly moves to the opposite side of the roadway and drivers can take free left turns because they do not cross opposing traffic.

“If you’re getting off the Interstate and you want to go north or south, it’s a continuous flow,” Charbonnet said. “There’s no light there.”

Mobile users see an example of the interchange here.

Charbonnet said engineers chose the diverging diamond design because it was one of the least expensive and least invasive options for people who live and work nearby. He said they expect only three properties will need to be relocated.

The total expense of building the interchange, which could be more than $55 million, needs to be funded by May 1 of 2017. The project already has more than $20 million set aside, which is a combination of local, state and federal money along with general obligation bonds.

Charbonnet said they hope to receive the additional $36 million from money in the state’s Capital Outlay budget or from the Department and Transportation and Development’s road transfer program. State Representative Steve Carter, R-Baton Rouge, was in attendance and said Green Light plan representatives need to make sure people in state government know the importance of funding the project.

“We’ve got a lot of projects that need to be funded, but we don’t have that many dollars,” Carter said. “It’s very critical for this group to get this as a high priority.”

State Representative Darrell Ourso, R-Baton Rouge, agreed. Ourso hosted the meeting and said local representatives “need to deliver the message that we want this project to happen.”

Shawn Wilson, the chief of staff for DOTD, said he cannot guarantee how much money DOTD will be able to make available for the project. Still, he said the interchange should be a priority because of its ability to reduce congestion on arterial roads.

“The fact that this has a hard deadline gives it a sense or urgency,” Wilson said. “We’re very sensitive of not wanting to go back into the studying phase of a project. We would hate to spend money that we could have reserved for construction to go to a study.”

Representatives from Congressmen Garret Graves and Senator Bill Cassidy’s offices also attended the meeting, and said the congressmen backed the project. But Graves’ chief of staff Paul Sawyer said Congress is no longer able to delegate federal money for such road projects the way that it formerly could.

Once the project is funded and construction begins, it is expected to take around two years for the changes to be complete. If everything stays on schedule, the Pecue/I-10 interchange should be completed around Christmas of 2019.

The planning for the interchange project should make a lot of progress during the first few months of 2016. After the Federal Highway Commission greenlights the interchange plans, Charbonnet said he hopes to hold a public hearing on the chosen design in late January.