Selected Projects

► Susquehanna River Bridge 60.07

► Jefferson & McDonough Bridges

► Robert Moses Causeway

► Stratford Avenue Bridge

► HX Drawbridge

Hundreds of movable bridges are in use in the United States. Maintaining a good balance state enhances the safety of the bridge while decreasing wear, maintenance costs and power requirements. Strain gaging balancing can be performed on most movable bridges including:

Vertical Lift Bridges

*  Tower Drive

*  Span Drive

Bascule Bridges

*  Scherzer

*  Strauss

Modjeski and Masters has developed movable bridge specific hardware that can determine the balance state minutes after testing. Based on our testing and analysis, owners can be given recommendations. Immediate adjustment of the balance state allows quick retesting of the leaf.

There are many signs that strain gage balancing should be performed. They include:
*  A recent increase in power required for leaf operation
*  Redecking or other changes to balance state
*  Verification of calculated balance state after rehabilitation
*  Poor operating characteristics during high wind or heavy snow load
*  Dirt accumulation and bridge deterioration
*  Hazardous operating characteristics (leaf tends to open when fully closed).

Strain gage balancing will yield:
*  Balance condition
*  Peak load in drive train
*  Drive train efficiency
*  Power requirements
*  Load sharing between pinions
*  Overall friction of leaf versus angle of height, and
*  Recommended weight adjustments and positions

Modjeski and Masters also performs the following related services:
*  Installing and monitoring strain gaged bolts
*  Strain gaging of bridge structures and monitoring of individual members
*  Cable load measurements
*  Full vibration analysis

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