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I-93 Expansion Ideas: A slowdown at Exit 12


Sunday, May 28, 2017


A satellite view of the current configuration at Exit 12

Planners and engineers have spent years whittling down ideas for improving and expanding I-93 through Bow and Concord. Now, it’s your turn.

Informational meetings have been scheduled for this coming week to discuss options for the four I-93 interchanges: The Bow interchange, including Exit 1 on I-89 and the interchange of I-89 with I-93; Exit 12 over S. Main Street; Exit 13 and the interchange with Route 3; and the long downtown overlap of exits 14 and 15.

This is the second of three articles about those options. On Sunday, the Monitor discussed options for the interchange of I-89 and I-93. Tomorrow, it will discuss options for exits 14 and 15.

The information sessions are set for Wednesday at Bow Memorial School and Thursday at Rundlett Middle School in Concord. Each meeting will begin with an open house from 4 to 6 p.m. with various concepts (generally three options per interchange) on display. A formal presentation will follow at 7 p.m., with opportunities for the public to ask questions.

Interstate I-93 was expanded to six lanes south of Concord many decades ago. This work contemplates widening 93 to six lanes through the city. 

The big problem from a traffic engineering point of view is that this entire stretch of road has too many high-speed interchanges too close together, forcing the backups and slowdowns that are a routine part of commuting life in Concord.

The entire project is likely to cost in the range of $200 million. A total of $61.4 million is included in the state’s 10-year highway plan through 2028, about $46.5 million of which is for actual construction starting in 2024.

Under the state’s 10-year highway plan, construction wouldn’t begin until 2024 at the earliest, preceded by years of engineering and obtaining rights of way.

The big problem at Exit 12 is that the off-ramps from I-93 to northbound and southbound on South Main Street (Route 3A) are too close together, leaving little room to slow down and use them.

The fix in both these options is to combine the two ramps  – that is, you take the same exit whether you plan to go north or south on Route 3A. Otherwise, the only big change would be to add another lane to the interstate in each direction.

– David Brooks


CONCEPT E

This option has both ramps ending on Route 3A with a signalized intersection. It would also widen the bridge over the railroad tracks and replace the bridge over Hall Street, which is red-listed.

PRO: Relatively cheap and easy.

CON: Traffic backs up at signals, and can potentially affect through traffic on the highway.


CONCEPT F: 

This is identical to Concept E, except the ramps intersect with South Main Street via roundabouts, rather than stop lights at intersections. 

PRO: No backups due to stop lights. 

CON: Would be the first hybrid roundabouts in Concord.