In August, the Andover Board of Selectmen and the Andover Road Agent had an opportunity to meet with Steve Liakos, retired senior New Hampshire Department of Transportation (DOT) bridge engineer. Steve’s work for DOT now involves helping towns by explaining inspection reports and the State Bridge Aid Program and offering advice on bridge projects.
We met with Steve at the Town Hall for about an hour. Steve came with the most recent bridge inspection report, a list of bridges and their structural ratings, and maps showing the location of all of Andover’s bridges. Andover is a “bridge rich” community, with a total of 33 state and municipal bridges. Of those, 20 are on Town roads and are the Town’s responsibility to maintain.
Steve explained the rating system used by the state DOT and how a bridge becomes “red listed.” The rating system goes from 0 to 9, with 0 being “failed condition” and 9 being in “excellent condition.” This rating system is applied independently to each of the three major elements that make up a bridge:
the decking, or driving surface
the superstructure, or beams that hold up the decking
the substructure, or piers or abutments that hold up the superstructure
Each of these three elements of a bridge receives a score from 0 (failed) to 9 (excellent). If any of the three elements receives a score of 4 or less, then the bridge is red listed, which means it requires inspections twice yearly.
Immediate Attention
We identified six Town bridges needing the most immediate attention and visited each one with Steve. We reviewed the most recent inspection, were given a “guided tour” of the superstructure and the substructure, and got recommendations from Steve for corrective action. The following is a summary of the findings on each bridge:
Morrill Hill Road Bridge: The Town is currently in a State Aid agreement with DOT for the replacement of the culvert and support structures. A State Aid project is a 20/80 split, meaning that the Town has to fund 20% of the total cost, while the State picks up the rest.
The funds for this project were raised in 2010, and the Town has already paid for engineering design and permits for the project. The State has not given this project priority, but Steve agreed that this is a necessary project that should be done as soon as possible and is well suited for State Aid. The Selectmen have made it clear to DOT that we want to move forward with the project.
Lawrence Street Bridge: The decking ( score of 7) and the beams (score of 8) of this bridge are in good condition. The wings and retaining walls (score of 5) show minor section loss, cracking, and spalling and may not be good candidates for rehabilitation. The railing and fencing on the pedestrian side need to be reinforced, and they are being repaired this fall.
Because of the poor condition of the substructure, setting a weight limit of 20 tons was recommended. The bridge will also be posted as a “one lane” bridge. These precautions are necessary because financial aid for the project will not be available until 2018 at the earliest.
The Selectmen have sent in a request for an estimate for the project, which will quickly be followed up with a request for aid. Even with state or federal aid, this will be an expensive project for the Town, and we will need to increase our annual contribution to the Bridge Capital Reserve Fund.
Hall Road Bridge: This bridge was built in 1932 and is on the Municipal Red List because of ratings of 4 (deck), 6 (beams), and 5 (abutments). The recommendation is for a new superstructure and rehabilitated abutments for a total length of 16 feet.
Elbow Pond Road Bridge: This bridge was rebuilt in 1964 and is on the red list with ratings of 5, 5, and 3. The recommendation is to build new abutments behind the existing abutments, effectively opening the channel flow. This will help prevent the overspill which often happens after heavy rains.
The steel beams should be replaced by 30-foot concrete beams or a precast rigid frame. Another option for this location is a modern timber bridge. Action must be taken soon, or the bridge may have to be closed.
Kearsarge Mountain Road Bridge: Built in 1950, this bridge is also red listed because of poor condition of the supports and the decking. This bridge is received a lot of use from logging trucks for a State forestry project this summer, adding greatly to the rate of deterioration.
Gale Road Bridge: This bridge has long been closed to vehicular traffic. A visit to this bridge with Steve Liakos showed failed support beams and abutments with severe scouring.
It was clear to all that the bridge should be removed before it falls into the river, which would cause a very costly mitigation. The plan for next year, therefore, is to hire a company that can remove the decking and superstructure completely, but leave the abutments in place. The cost should be less than $10,000.
Making It All Happen
The bridges on Elbow Pond Road, Hall Road, and Kearsarge Mountain Road are relatively small projects (each one approximately $30,000 or less) that the Town can fund without State Aid, but they are priority projects and must be addressed within the next two years. Steve explained that small bridges can deteriorate very rapidly, as opposed to the slow, steady deterioration of larger bridges.
The Selectmen and the Road Agent will be putting a funding plan together to present to the Andover Budget Committee in November. As for the bridge replacements and rehabilitation, Steve will do free, non-binding reviews of bridge projects done by the Town. His visit with us was very instructive and helpful, and he is eager to help us see these projects through.