Bay Crane uses a “Jumper Bridge” to protect the Brown Avenue overpass of Cohas Brook. The temporary steel decks span the bridge structure so the load weight is supported on the ground ( not bearing on the bridge) preventing collapse during the transformer transport. Photo/ Dan Splaine Photography

Right after the dramatic thunderstorm rolled through southern NH on Tuesday night another equally if not more impressive drama began. A caravan of trucks, cranes, heavy equipment, and one huge specialty tractor-trailer assembly escorted by multiple State Police and NH Highway department cars began a slow journey from Manchester.

Eversource Energy had a large transformer to deliver to their Scobie Pond Sub-Station in Londonderry. They enlisted Bay Crane a heavy transport and specialty rigging company to transport the 490,00-pound power transmission equipment.

To move the equipment they used a double drop deck trailer with 12 separate axles with 8 wheels each, designed to disperse the massive load weight over a wide area of road surface. The truck and load had an overall vehicle length of 181′ with a combined weight of 752.000 pounds.

Beginning at 9:30 pm, the move took over 5 hours to travel the 10-mile route. A team of dozens including utility crews, riggers, drivers, crane operators, engineers, and DOT employees worked during the well-choreographed operation.

The truck and trailer assembly before the move. The truck and load had an overall vehicle length of 181′ with a combined weight of 752.000 pounds. The railroad car on the siding next to the transformer indicates the large scale of the equipment. Photo/ Dan Splaine Photography

Bay crane used a “Jumper bridge”, a temporary platform designed to span over the existing bridge. Two arched steel assemblies longer than the bridge span are placed over the actual bridge structure so the weight of the load does not bear on the bridge. During the move, the crew used this system over three locations on the road, one on Brown Avenue in Manchester and two on Route 28 in Londonderry.

At the bridge on Brown Avenue over Cohas Creek, An additional 8-wheel drive OshKosh Heavy tractor was brought in to push the trailer and provide extra to move the assembly over the “Jumper Bridge” adding another 24’ to the vehicle length.

The brown Avenue crossing can be seen in this video.

The move was scheduled at night and the route selected was designed to have the least traffic impact. A rolling series of closures occurred and were safely managed by the team of state police escorts.

The planning and coordination paid off and the transformer was safely delivered on schedule.