|Project 0082-0316 - Route 9 Middletown|
About the Project
The State of Connecticut Department of Transportation (Department) is currently developing plans to reconfigure the Route 17 on-ramp to Route 9 northbound. State Project Number 0082-0316 is located in downtown Middletown on Route 17 between South Main Street and Washington Street. The purpose of the project is to improve safety by reducing crashes at the interchange. This project is needed because the existing stop-controlled on-ramp from Route 17 onto Route 9 northbound has a crash rate significantly higher than similar adjacent freeway segments.
Route 17 is a north/south running roadway that connects Glastonbury to New Haven and is classified as an Urban Freeway within the project limits. The Route 17 on-ramp to Route 9 northbound is a skewed stop-controlled intersection with a short acceleration lane just before Bridge No. 00638 that carries Route 9 over Union Street and an active Providence and Worcester (P&W) rail line. The superstructure is rated 4, poor condition, based on the latest Bridge Safety Inspection Report dated March 31, 2020. The existing superstructure design prevents proper maintenance of the bridge and has therefore deteriorated. Other structures within the project limits include Bridge No. 00861 (substructure rating 5) carrying Route 17 northbound over East Main Street and Bridge No. 00636 (superstructure rating 5) carrying the Route 17 on-ramp to Route 9 northbound over Route 9./p>
The existing geometry of Bridge No. 00636 restricts sightlines approaching the stop controlled on-ramp and therefore hinders the driver’s ability to see queued vehicles at the stop-controlled intersection with Route 9 northbound. Additionally, Route 17 intersects Route 9 at a 25-degree angle on the inside of a curve, forcing drivers to look behind them for approaching vehicles on Route 9. A common occurrence is for the second queued vehicle to accelerate into traffic before the first vehicle has accepted a gap, leading to a rear end collision at the stop sign. This can be attributed to the heavy skew of the interchange, causing the second driver to focus on the Route 9 traffic as opposed to the vehicle in front of them.
After selecting a gap in Route 9 traffic, the driver is only provided approximately 100 feet to accelerate from a full stop to 55 miles per hour. This short acceleration lane, combined with the poor sightlines and heavy congestion, lead to a driver accepting a gap that they normally would not. In turn, this contributes to the higher than expected rear-end crash rate.
Route 17 intersects Main Street Extension in an offset diamond configuration interchange, with Bridge No. 00860 (superstructure rating 5) carrying Route 17 over Main Street Extension. The on-ramp from Main Street Extension to Route 9 northbound requires the driver to navigate a 300-foot weave and lane drop prior to the split with the Route 9/17 interchange. Within the vicinity of the interchange is Hubbard Park which abuts the Route 17 southbound off-ramp to Main Street Extension. Bridge No. 00862 (superstructure rating 6) is located directly east of the offset diamond interchange and carries Route 17 southbound over East Main Street.
Union Street is an east/west running local road that provides the primary access to the waterfront from downtown Middletown and splits into a “Y” type intersection with River Road and Harbor Drive. Harbor Drive provides access to Harbor Park to the north and intersects Route 9 northbound with a short acceleration lane that is used as an alternative to the Route 17 and Route 9 northbound stop-controlled interchange.
The substandard elements above also compel drivers to avoid the interchange as a whole and opt for another entrance to Route 9. This is illustrated by the results of an origin and destination study of the downtown Middletown area. The study showed that a large number of vehicles are avoiding the stop-controlled interchange in lieu of the Harbor Drive on-ramp. This on-ramp is itself substandard, with a short acceleration lane and poor sightlines. Upon completion of this project, the Harbor Drive on-ramp will be closed, as keeping it open would create an unsafe weave condition on Route 9 due to its proximity with the Route 17 on-ramp. Due to this closure, a large number of vehicles will be redistributed to the Route 17 interchange with Route 9. In order to accommodate this increase, improvements to the Main Street Extension and Route 17 interchange will be required.
The proposed work includes providing a full-length acceleration lane for Route 17 northbound traffic to merge onto Route 9 north. A full structure replacement will enable widening the structure to the west as well as addressing maintenance concerns while allowing flexibility in pier placement. The proposed acceleration lane will require realignment of Route 9 as well as the closure of the Harbor Drive on-ramp onto Route 9.
The existing weave on Route 17 northbound was analyzed using VISSIM and HCS. It was determined that the congestion experienced on the weave was a result of the traffic signals on Route 9 and that a two-lane cross section has adequate capacity. This two-lane section allows us to maintain the existing sight distance through the curve.
After closure of the Harbor Drive interchange, the Main Street Extension and Route 17 interchange will serve as primary access to Route 9 for the southern section of downtown Middletown. Consequently, traffic volumes would increase at the interchange and operate at a failing level of service under the anticipated traffic volumes. The proposed improvements include reconfiguring the interchange and signalizing the northern intersection. Dedicated turn lanes will be added on Main Street Extension and the Route 17 off-ramps to increase traffic capacity. The Route 17 southbound on-ramp will be realigned with the Route 17 southbound off-ramp to create a more typical intersection configuration and will be signalized.