The Colchester I-89 Bridges Project rehabilitated four bridges along I-89 in Colchester, Vermont. The four bridges are 76 North and 76 South over Bay Road, and 77 North and 77 South over Mallett’s Creek. The project replaced the existing heavily deteriorated bridge decks with new precast deck panels. Concrete was replaced on the bridge back walls and approach slabs, and minor steel and concrete repairs were completed on the abutments and piers. This project was time-sensitive and phased construction methods were used to maintain two-way traffic on I-89 throughout construction. The majority of the construction activities, including the four bridge replacements were completed during the 2019 construction season. In Spring 2020, crews returned to complete the minimal remaining punch list items, including remaining slope grading work, completing bridge joints, placing topsoil and planting grass. The contractor operated under single lane closures during non-peak hours. The project was completed in June 2020.
Contract Award: February 2019
Construction Start: April 15, 2019
Bridge Closures: July 19 – September 23, 2019
Construction Completion: June 5, 2020
VTrans Project Manager: Todd Sumner, P.E.
VTrans Resident Engineer: Chris Lavalette
Designer: VHB, Inc.
Contractor: Kubricky Construction Corporation
Public Information Consultant: Annabelle Dally, WSP USA Inc.
- The four bridges are located in the Town of Colchester in Chittenden County on I-89 between Exit 16 and Exit 17.
- Bridges 76 North and 76 South, over Bay Road, are located on I-89 approximately 3.8 miles north of Exit 16 at mile marker 95.3.
- Bridges 77 North and 77 South, over Mallett’s Creek, are located on I-89 approximately 1.3 miles south of Exit 17 at mile marker 96.6.
- Bridges 76 North and South are approximately 1. 3 miles south of the 77 North and South bridges.
The existing bridges are 3-span continuous rolled beam bridges constructed in 1964. Bridges 76 N&S over Bay Road are 157-feet in length and Bridges 77 N&S over Mallett’s Creek are 185-feet in length. All four bridges have beams and substructures that are in satisfactory condition, but decks that are in fair to poor condition with heavy deterioration in some areas, and leaky bridge joints. The bridge railings are not in line with today’s safety standards and need replacement.
VTrans evaluated alternatives for rehabilitation or replacement of the bridges in an engineering study completed in December 2014. The study assessed proposed design criteria for the bridges, along with impacts on rare, threatened and endangered species, archaeological and wetland resources. Several alternatives were considered including no action, minor patching, deck replacements, superstructure (deck, fascia, bridge rail) replacements, and full bridge replacements.
The engineering study recommended deck replacements with minor substructure (foundation, abutment, pier) repairs.
The decks were replaced using Accelerated Bridge Construction (ABC) methods. The new full-width precast deck panels were cast in advance, off-site, and then placed in 8-foot length segments. Each bridge has two 12-foot lanes with a 4-foot shoulder on each side.
Work on the project began on April 15, 2019. I-89 remained open throughout construction. There were six weekend closures of the bridges between July 19 and September 23, 2019. The closures began at 7:00 PM on Friday and ended at 6:00 AM on Monday. Two-way traffic was maintained via crossovers. Crossover traffic patterns were used between July 19 and October 11, 2019.
- 1st closure: I-89 weekend closure at Bridge 77 North over Mallet’s Creek for two days from 7 PM July 19, 2019 – 6 AM July 22, 2019
- 2nd closure: I-89 weekend closure at Bridge 76 North over Bay Road and Bridge 77 North over Mallet’s Creek for two days from 7 PM July 26, 2019 – 6 AM July 29, 2019
- 3rd Closure: I-89 weekend closure at Bridge 76 North over Bay Road for two days from 7 PM August 9, 2019 – 6 AM August 12, 2019
- 4th Closure: I-89 weekend closure at Bridge 76 South over Bay Road for two days from 7 PM September 6, 2019 – 6 AM September 9, 2019
- 5th Closure: I-89 weekend closure at Bridge 76 South over Bay Road and Bridge 77 South over Mallett’s Creek for two days from 7 PM September 13, 2019 – 6 AM September 16, 2019
- 6th Closure: I-89 weekend closure at Bridge 77 South over Mallett’s Creek for two days from 7 PM September 20, 2019 – 6 AM September 23, 2019
The contractor had 11 weeks to complete the six closures during July, August, and September 2019. For each weekend closure, the contractor had 59 hours to complete the work.
On weekdays the contractor used crossovers traffic patterns to maintain two lanes of traffic in the peak direction and one lane in the off-peak direction during high volume times of the day.
This project was the first time VTrans implemented directional crossover traffic patterns, as follows:
- One lane per direction during the weekend closures
- Two lanes southbound, one lane northbound during the weekday AM peak hours
- Two lanes northbound, one lane southbound during the remaining weekday hours
The timing of the crossover patterns was determined using traffic counts and occurred at times of lower traffic to reduce congestion.
Navigational signage was in place to guide motorists through the crossovers and changing traffic patterns.
Bay Road and the bike path were closed on two weekends, from 7 PM August 9, 2019 – 6 AM August 12, 2019, and again 7 PM September 13, 2019 – 6 AM September 16, 2019, when the decks of Bridge 76 North and South were demolished. A local detour route was signed for motorists and bicyclists.
The majority of the construction activities, including the four bridge replacements were completed during the 2019 construction season. In Spring 2020, crews returned to complete the minimal remaining punch list items, including remaining slope grading work, completing bridge joints, placing topsoil and planting grass. The contractor operated under single lane closures during non-peak hours. The project was completed in Spring 2020.