It is one of the major questions facing the state gambling commission: Which infamous Boston bottleneck will get the bulk of new casino traffic?
Should it be Route 1A in East Boston? The often jammed-up commuter highway, and a key local road for East Boston, Revere, and Winthrop?
Or should it be Sullivan Square in Charlestown, where residents have waited decades for a traffic fix?
For all the differences between rival casino proposals by Mohegan Sun in Revere and Wynn Resorts in Everett, both have raised concerns from transportation experts that they could make the region’s famously bad traffic even worse.
“Both of them have very large and, on the face of it, unmitigatable problems,” former Massachusetts Transportation Secretary Fred Salvucci, said of the two proposals.
The developer that better deals with traffic — not just for customers, but for everyone who uses those congested roads — will gain an advantage in the competition for the Greater Boston casino license. The state gambling commission, which is scheduled to issue the license by August, is currently evaluating the rival transportation proposals, with help from experts.
“It’s an issue at the forefront,” said gambling commissioner Gayle Cameron, who is leading the team reviewing the traffic plans.
Casino companies are sensitive to public concerns about traffic, an issue often used by opponents to fight the industry. There are also powerful financial incentives for casinos to avoid making traffic worse — customers can’t risk their money if they can’t get to the tables and the slot machines.
A new casino on the city’s border could generate more than 20,000 new car trips a day, according to documents filed by both companies. That’s roughly as much new traffic as a Walmart and a busy supermarket combined.
To ease potential traffic delays, Mohegan Sun and Wynn have each pledged millions of dollars toward improving roads and intersections, and have put forth plans to encourage mass transportation to take cars off of the roads.
And both companies emphasize that their peak traffic times do not correspond with the worst commuter traffic, a claim that is “fairly accurate,” said casino executive and consultant Saverio R. Scheri, president and chief executive at WhiteSand Gaming.
“If you think of the people who generally visit casinos mid-week it’s often retired people,” said Scheri. “They’re older; they’re certainly not going to get up and fight rush hour traffic to go anywhere.” Some casino traffic could affect the evening commute, especially on Fridays, but generally “the peak drive times are a little different. It’s a little later at night. It’s on the weekends.”
Cameron said it is too soon to know which traffic proposal is better, and that the proposals will continue to be refined as plans are vetted through the state’s standard development review for large projects. She also noted that the casino companies are also still in negotiations with surrounding communities, and that some of those deals are expected to contain money to address traffic.
For Mohegan Sun’s proposal at Suffolk Downs, the obvious traffic hot-spot is Route 1A; a majority of the resort’s traffic would arrive through tunnels from Boston and onto 1A, according to the developer’s projections.
“They would be adding more cars to a nightmare that already exists,” said Joe Catricala, a Revere resident leading the local opposition to the Mohegan Sun plan.
Mohegan Sun has projected that about 84 percent of patrons would arrive by car or taxi, 11 percent by public transit and 5 percent by shuttle bus or coach, according to documents filed with the gambling commission
The Connecticut gambling company has pledged to spend more than $45 million on a traffic plan that “improves existing conditions at every location contemplated,” said Mitchell Etess, chief executive of the Mohegan Tribal Gaming Authority.
The centerpiece of the plan would be one of two options: Building a Route 1A flyover at Boardman Street in East Boston, or an alternative intended to expand capacity and introduce new traffic lights that work in sequence, moving traffic more efficiently.
The flyover was a key selling point in an original Suffolk Downs casino proposal in East Boston, which failed when Eastie voters rejected the project in a referendum last November. Mohegan Sun retained the flyover concept when the company agreed with Suffolk Downs to lease land for a casino just over the city line in Revere, though the flyover may not be built.
Etess said state transportation officials will decide which Route 1A option is best “and we’ll write the check” to pay for it.
Mohegan Sun also proposes to pay for numerous other road and signal improvements at area intersections.
“When we’re done, traffic will be better for everyone,” said Etess.
Not everyone is convinced the plan goes far enough.
“The $45 million in infrastructure spending by the private sector is, on its face, wholly inadequate to resolving critical traffic congestion and public safety issues raised by the scale and location of the proposed development,” former state transportation secretary James Aloisi wrote in a statement he submitted during the public comment period on the project’s environmental review.
And while Mohegan Sun officials say the casino would not affect traffic in the Boston tunnels, Salvucci, the other former transportation secretary, wants to see data — now being collected for the project’s environmental review — to back up the assertion.
“This is about regional access to the Innovation District [in Boston] and regional access to the airport,” he said. “To risk that over a casino is crazy.”
The best feature of the Mohegan Sun transportation plan, according to Richard McGowan, a Boston College casino expert, is its focus on the MBTA and the nearby Blue Line Beachmont Station.
“The Suffolk Downs location has a much more realistic site for using public transportation,” said McGowan, who believes both casino sites face significant traffic problems. “But how many people really go to a casino on public transportation?”
Etess said the company designed a grand public entrance for the resort across from the T station, to encourage more customers to come by train.
“We’ve put a lot into that entrance and it speaks to how important the T is to us,” he said.
For the Wynn Resorts proposal on the Mystic River riverfront in Everett, the preeminent traffic trouble spot is Sullivan Square, a major intersection through which a majority of the resort’s arriving traffic is expected to pass, according to company projections.
“The concern is we would be seeing a significant diminution of our quality of life,” said Ivey St John, a Charlestown resident who has raised questions about the project.
Wynn has projected that 77 percent of the resort’s patrons would arrive by car or taxi, 10 percent by the MBTA Orange Line — connecting to shuttle busses the resort would run to nearby MBTA stops — 10 percent by tour bus and 3 percent by shuttle boat on the Mystic River.
Wynn has committed to pay for about $40 million in traffic improvements, said Wynn project manager Chris Gordon.
“We’re not afraid of some of the big issues,” he said. “We think we can be part of the solution.”
The city of Boston Transportation Department disagrees, saying in a February letter to state officials that that the Wynn plan “does not thoroughly or accurately describe the transportation impacts of the project in Boston, nor does it offer adequate mitigation of those impacts.”
Wynn has proposed $5 million to $6 million of work in Sullivan Square that Gordon says would offset the traffic added by the resort. The proposed work would widen Cambridge Street and install new traffic signal technology, he said.
“I don’t want to tell you that all of Sullivan Square in Charlestown will work perfectly because it will still have challenges, but at least it mitigates our traffic,” he said of the proposed improvements. “Beyond that we’ve committed to participate with the City of Boston — they’ve got a big plan for a big fix in Sullivan Square — we’ve committed to be part of that. And when I say committed, we’ve agreed to put money into that, including funding the design process.”
Salvucci still questions whether Sullivan Square can handle the traffic from such a major development.
“Have you driven through Sullivan Square?” he said. “It’s very close to capacity much of the day.”
Wynn has also proposed improvements at major intersections along Route 16, and would widen a section of Broadway in Everett, among other proposals.
The developer has committed to paying for a study and design for improvements at another traffic trouble spot, Wellington Circle in Medford. State transportation officials say the casino project “is expected to worsen conditions” at Wellington, and have called for the company to develop a solution.Mark Arsenault can be reached at firstname.lastname@example.org.