More than a half-century after Congress authorized building a replacement for the Industrial Canal's navigation lock, optimism is rising among some maritime industry officials that the nearly $1 billion project is about to happen.

The hope is built on President Donald Trump's calls for spending up to $1 trillion to shore up the nation's aging infrastructure. But nothing is certain, and hopes have risen before.

The lock, which began operating in 1923, is situated where the Mississippi River intersects the Gulf Intracoastal Waterway, a 1,300-mile inland system of system of channels and tributaries running from Brownsville, Texas, to St. Marks, Florida. The waterway is used by commercial as well as pleasure boats to provide protected passage inside the Gulf coastline.

If the lock should go down, the impact would clog the entire waterway system, with the only viable alternate taking 17 days to traverse, according to the U.S. Army Corps of Engineers.

The inland waterway is the nation's third-busiest in terms of tonnage carried, accounting for about 116 million tons of commodities that are transported annually, worth close to $86 billion, according to the data from the Gulf Intracoastal Canal Association. The trade group represents the waterway's users, such as tow and barge operators, shippers and others.

The largest category of the commodities that pass through is petroleum, followed by chemicals.

A chorus of voices, including industry officials and the Corps, which operates the lock, contend that it is outdated and too small for modern shipping vessels.

"It's quite similar to going to the deli," said Victor Landry, the Gulf Intracoastal Waterway operations manager for the Corps’ New Orleans District. "You take a number and you wait for your turn to get your meat. It's kind of like that for the barge industry here. As they're getting close, they call the lock operator and get on 'lock turn,' which could take two days."

The bottleneck has led to delays for large cargo ships and barges and pushed the average time for a tow vessel to get through it to about 16 hours: more than 15 hours waiting to enter the lock and 44 minutes to actually go through it.

But many nearby neighborhood and environmental groups have long opposed the decades-old proposal to widen the lock. They say the project will cause environmental hazards and disrupt surrounding neighborhoods during the several years required for construction.

What's more, they say, the project is no longer worthwhile, given the relatively little traffic that the 5.5-mile-long Industrial Canal — officially the Inner Harbor Navigation Canal — sees nowadays.

However, the Corps says the traffic is low because of the inadequate lock, which is 640 feet long by 75 feet wide — far too small for modern vessels. The costs of operating and maintaining the old lock also have risen over the years, officials say.

Earlier this year, the Corps put forward a tentative plan to replace it with a 900-foot-long, 110-foot-wide and 22-foot-deep shallow-draft lock, which would cost an estimated $951.3 million.

It would be built north of the Claiborne Avenue Bridge and south of the Florida Avenue Bridge.

Landry doesn't mince words when describing the challenges that the aged lock poses to the industry. "Bottom line: It's a bottleneck. It's a chokepoint for everything on the GIWW," he said.

The delay stems from the lock’s limited capacity compared with the high volume of traffic and the size of vessels navigating the Gulf Intracoastal Waterway and Mississippi River.

Throughout last year's presidential campaign, Trump talked broadly about implementing a massive federal spending initiative to upgrade the nation's infrastructure. In June, he touted his plans in a visit to Cincinnati, highlighting the nation's aging locks, levees and ports at a stop near the Ohio River.

Ahead of his inauguration, a widely circulated list of potential infrastructure targets included the Industrial Canal lock replacement among 50 U.S. projects, worth at least $137.5 billion in spending, according to a report in the Kansas City Star.

Besides the lock, two other Louisiana projects made the cut. Dredging the lower Mississippi River to a depth of 50 feet to accommodate larger ships was one project. The other was improvement work on the Lake Pontchartrain Causeway, a potentially $125 million project that calls for building higher guardrails on the southbound span and new "safety bays" on both spans to allow drivers to pull over in case of mechanical problems.

Having made the cut is a good sign for officials who have long been tracking the Industrial Canal project's progress.

"It underscores how important that lock is and how vital those waterways are to the national economy," said Corps spokesman Ricky Boyett.

Now, some maritime leaders are waiting to see if the president follows through.

"I'd like to know the answer myself," said Michael Toohey, president and CEO of the Waterways Council Inc., a trade association for shippers and carriers based in Arlington, Virginia.

Still, Toohey remains "very optimistic" that the lock replacement will finally get done, though he anticipates infrastructure spending will remain on the back burner until the White House tackles tax reform.

Not all officials are in favor of the project. Critics of the plan, including state Sen. JP Morrell, contend that the Industrial Canal has seen a drop-off in activity since a portion of the Mississippi River-Gulf Outlet was closed to maritime traffic in 2009.

The lock project would be funded jointly by the Corps and the federal Inland Waterways Trust Fund, which gets money from taxes on cargo. But the money would need to be included in a future congressional appropriation.

Before that happens, the Corps is slated to make a final decision on the project at the beginning of 2018. From there, it will host public meetings to gather feedback before issuing a final report, likely in June . If senior Corps leaders agree, the report will be forwarded to Congress for authorization.

Though replacing the lock has been discussed for decades, the plan was dealt a setback in the aftermath of Hurricane Katrina. In 2006, U.S. District Judge Eldon Fallon barred the Corps from moving forward with the project until the agency conducted additional research to determine potential impacts from hurricanes and flooding.

The Corps concluded that work in 2009. Two years later, the judge instructed the Corps to consider the impact of the closing a portion of the Mississippi River-Gulf Outlet to maritime traffic.

Meanwhile, it's not as though the lock has gone untouched. Last year, the Corps undertook $20 million in maintenance work on it, a process that lasted 120 days and forced the lock to be emptied and closed to vessels. The work included replacing aging, outdated equipment with new gates and hydraulic machinery.

Now, instead of fabricating parts or cannibalizing old motors when another one goes down, the Corps can order replacement parts if needed.

During the maintenance work, vessels that otherwise would have traveled the Industrial Canal relied on an 85-mile alternate route created by dredging the Baptiste Collette Bayou, which allowed shallow-draft vessels to go through the Breton Sound to the Gulfport Ship Channel.

The lock is situated near many businesses and residences, which has been the source of some of the criticism. By now, though, the Corps has already acquired any property that's needed for the proposed replacement, and the agency may offer nearby residents the chance to temporarily relocate during construction.

The Corps estimates that building the replacement lock would take about 13 years, although that timeline could be trimmed to eight if it had all the money upfront.

Some maritime officials say they've waited long enough for the new lock, but they still are not certain whether it will be built.

"The chances are certainly increased, but given some of the challenges in D.C. with Congress and the president, it's tough to tell whether it's going to happen," said Mark Wright, vice president for the southern region of the American Waterways Council, another trade group.

In a 2015 letter to the Corps, Wright described the lock as "a critical component" and said a replacement would offer myriad benefits: lower maintenance costs, reduced traffic congestion and fewer barges stuck waiting near the lock.

The current design is also backed by the Port of New Orleans. "A new lock would operate more efficiently for commercial marine traffic and provide a safer, more reliable bridge for motorists. Additionally, if a new bridge is funded with federal dollars, port funds can be invested in other projects," port spokesman Donnell Jackson said.

Spencer Murphy, general counsel and vice president at New Orleans-based Canal Barge Co., described the problem as "a capacity issue," and said the Corps' tentative proposal represents "a healthy compromise" that's "certainly better than what is there now."

"It's past its prime for replacing," he said.

Follow Richard Thompson on Twitter, @rthompsonMSY.