Of all the toll locations the state Department of Transportation has studied, placing tolls at an interchange where an extended Route 11 would meet two interstate highways is the option it prefers.

But department officials said Wednesday they need to analyze further how tolls at those locations would affect traffic.

The DOT is studying the environmental, engineering and financial effects of adding 8.5 miles to Route 11, which now ends in Salem, and building an interchange with routes 95 and 395 at its proposed terminus. Construction on the route's extension through Salem, Montville, East Lyme and Waterford halted in the 1970s.

A bill to establish tolls on Route 11 didn't make it out of the legislature this year.

The DOT's preliminary study on potential toll revenue and traffic concluded that the interchange is the only viable option out of several others that included placing tolls along the Route 11 extension, said Tom Maziarz, DOT's bureau chief of policy and planning, in a presentation Wednesday to the Route 11 Greenway Authority Commission.

The DOT is assuming the state would bond the estimated $1.4 billion project and begin construction in 2020. Tolls on the interchange alone could gross between $38 million and $69 million per year, and would pay back 31 percent to 57 percent of the state's debt service, he said.

But some local elected officials questioned the study's assumption that state bond funds would be the only source of support for the highway other than tolls, since federal dollars often fund transportation projects.

Current federal law bans tolls on interstate roads - such as routes 395 and 95 - except for certain "pilot programs," according to the presentation.

The study raises the possibility that the ban could be lifted with the reauthorization of the federal transportation act within two years.

The DOT presented four other alternatives. Tolls, at 20 cents per mile, on the Route 11 extension alone would gross $5.9 million per year (about 5 percent of the assumed debt service), but could discourage drivers from using the extension and could lead 60 percent to 70 percent of the traffic staying on Route 85, the study found.

Another option, tolls on both the Route 11 extension and the existing Route 11, would gross $8.5 million per year (7 percent of the assumed debt service), but could divert traffic to Route 85 north of Route 82 in Salem, according to the study.

Placing tolls on the extended and current Route 11, as well as on Route 2, would generate $28 million per year (23 percent of the assumed debt service), but could divert drivers from Route 2 onto other roads, the analysis found.

Installing tolls on both the Route 11 extension and the interchange would generate about $46 million to $78 million a year (36 percent to 65 percent of the assumed debt service), but would not remove as much traffic from Route 85 as the state would want.

State Rep. Ed Jutila, D-East Lyme, recommended two sets of analyses, one based on 80 percent federal and 20 percent state funding and the other based on a 50-50 cost sharing.

East Lyme First Selectman Paul Formica said the report should include analysis of other amounts, such as a 50-cent toll.

DOT officials said they will compile their final report and consider additional ways to analyze and present the results. Maziarz noted that Route 11 is competing against other transportation projects. He further stressed that tolling was just one aspect of the department's financial analysis of Route 11.

k.drelich@theday.com