How to best rebuild the massive, elevated I-84 viaduct flowing through the center of downtown Hartford remains an open question and state officials find themselves facing a dizzying array of engineering questions and lots of numbers.
The estimated cost to eliminate the elevated portion of highway, and lower the road to at or below grade, is $4.3 to $5.3 billion.
"There's a lot of interest in the lowered highway alternative," said Richard Armstrong, an engineer with the state Department of Transportation.
Armstrong said that lowering the highway would require relocating a railroad in downtown Hartford, which could have a significant effect on local properties.
"There are apartment buildings. There are some historic structures that may be impacted," said Armstrong.
About 175,000 cars use the 2.5-mile stretch of highway daily. Traffic accidents are substantially higher than rates on comparable roads in the state and traffic jams are a regular occurrence.
Tom Maziarz at the DOT said the I-84 project is a chance to right past mistakes.
"It gives us the opportunity to undo a lot of the damage that was created in 1965 when the highway was essentially was built right through the center and the heart of the city," said Maziarz, "and not only split neighborhoods, but split the business district -- split a park in one case -- and it really disrupted the local road network."
This month, Governor Dannel Malloy released numbers attempting to quantify the economic value of the highway.
The governor's office said billions of dollars in economic activity would be gained from replacing the viaduct, but the analysis wasn't based on comparing the old highway to a new one. Instead, it compared the new highway to, eventually, no highway -- an unlikely "worst-case scenario" that assumes the viaduct will fall into disrepair, deteriorate, and be closed by 2026.
That baseline was questioned by the state's Transportation Finance Panel this month.
In an email, Tom Maziarz said the DOT is now working on another economic analysis looking more closely at the value of just the improvement itself.