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Borough Seeks State, Somerset County Approval for Lowering Princeton Avenue Speed Limit

By Rikki N. Massand | Posted October 26, 2023

At its Monday, October 2 meeting Rocky Hill Borough Council unanimously approved a resolution seeking permission from the NJDOT and Somerset County to lower the speed limit along Princeton Avenue to 25 mph.

The step of approving an official resolution came after a few meetings of Council considering safety plans. Council member Susan Bristol asked for points of comparison on the Rocky Hill roads including Montgomery Avenue and Merritt Avenue, roadways with similar residential presence to Princeton Avenue. Both of those roads have a speed limit of 25 mph.

Princeton Avenue in Rocky Hill.

Bristol said the proposal to lower Princeton Avenue to the 25 mph limit to match the other local roads should “make total sense” to the State DOT and County. Borough Engineer Rob Martucci then explained that the DOT’s interpretation of local roads does include the inter-municipal roads. “I am glad Rocky Hill can be consistent across the board and just keep those roads at as low a posted speed limit as possible,” Bristol commented.

Before the approval, Council President Trey Delaney asked Martucci about the process of “selling” the lower speed limit to government agencies with authority, but the procedures are mainly technical and based on a series of recommendations and reviews. Posted speed limits on white signs, with black letters, need to be approved by NJDOT in order for police to enforce it for traffic.

Martucci explained that besides his professional engineering judgment, the forms for input to the State DOT must be based on the data and information contained in the NJDOT’s Design Manual and technical standards for construction, as well as the Manual on Uniform Traffic Control Devices (MUTCD) administered by the Federal Highway Administration. “Those are the documents I used to determine the maximum safe speed and appropriate markings on the road,” Martucci noted.

When Delaney asked about 25 mph versus 30 mph Martucci said the potential exists for cars to “bottom-out” and sustain damage if an elevated hump is traversed at a higher speed than 30 mph. “In my opinion the way speed humps are currently built, the design is for a vehicle to travel the speed limit and still safely travel over these humps, which is the ITE standard,” he told Council.

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Councilmember Jon Lee added that originally the speed reduction proposal included lowering the speed limit at the start of the hump to 15 mph, and Martucci noted guidance indicating that the speed can be lowered another 10 mph from the posted limit if necessary due to road conditions. He told Lee and Council the smaller yellow signs that can be placed at the hump are interpreted as a ‘warning’ or recommended safer speed, and Council can choose to include them if it prefers. No action on the warning or recommended lower speeds followed with Council’s action on October 2.

Rocky Hill’s resolution also had to include notification to the neighboring municipality of Montgomery Township. The State of New Jersey Law concerning Speed Humps, with Chapter 110 supplementing Title 39 of Revised Statutes, section 2C notes: “Prior to a municipality or county constructing a speed hump which places any impact on roadways in an adjoining municipality or county, the governing board or body of the municipality or county shall provide appropriate notice to the adjoining municipality or county.”


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