Town of Derry

NH Route 28 Improvements

Derry, NH

Project Summary

The NH Route 28 Improvements Project covers an area that accommodates 22,000 vehicles per day and numerous business and side road access points. Hoyle Tanner was selected to help alleviate a traffic “bottle neck” within the heavily traveled commercial district. Existing signalized and non-signalized intersections were first analyzed, then animation models were created to visualize the proposed additional signalization and roadway widenings. An added thru lane, turning lanes, and interconnected signal system increased roadway capacity and improved traffic operations.     

Early project efforts included stormwater coordination with the design of a large off-site commercial development located up gradient in the watershed. Stormwater analysis of existing conditions involved complex urban open and closed combined systems. The drainage design included the retrofit of existing conveyances to update aged infrastructure, meeting pre- vs. post-runoff requirements resulting in minimal impacts to upstream and downstream conditions. A porous pavement sidewalk was added to the design to decrease the volume of water exiting the site by infiltration. Hoyle Tanner assisted the Town with Right-of-Way negotiations by providing site impact plans and alternative development concepts. Three-Dimensional modeling was utilized to map existing underground utilities. Utility conflicts were minimized by designing around existing structures and lines where possible. Hoyle Tanner prepared the contract documents, assisted the Town in bidding, and was responsible for construction administration, and resident engineering. 


  • Final Design 
  • Stormwater Management 
  • Permitting 
  • Traffic Analysis / Study 
  • Signalization 
  • Traffic Control/Management 
  • Construction Observation 
  • Construction Administration 

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