Municipal Bridges – Maintenance Recommendations for Municipalities
By Daniel S. Crovo, P. E., District 5 Bridge Engineer

The lack of simple bridge maintenance in many Massachusetts municipalities is significantly affecting bridge structural capacity, personal safety, and overall condition. Under Federal law, MassDOT inspects, or receives inspection reports on all bridges on public highways in the state every two years. These reports must be reviewed by MassDOT within 90 days of the field inspection. The reports are then sent to each municipality.

In these biennial inspections, the MassDOT inspection crews typically find that municipal bridges and minor spans are not well maintained and very little attention is generally paid to them. If a major concern is evident, then MassDOT will immediately contact that municipality. In some cases, bridges have been closed or severe restrictions have been recommended to the local municipal officials.

It should be noted that MassDOT simply performs the inspection and makes recommendations on weight posting, repairs, or other limitations. In some cases, MassDOT may provide limited engineering services and other assistance through the District Bridge Engineers. However, the maintenance of minor spans on town ways and low-use bridges is the full responsibility of municipalities.

It is recommended that all towns budget for basic maintenance, deck repair, paint, and other minor repairs. Otherwise, it is likely that more expensive repairs or full replacement will face decision-makers in the future. Here is a checklist of basic maintenance which municipalities should perform on their bridge(s) and/or minor spans:

Annual Cleaning

Remove all sand and debris from the deck and around beams at least once a year (preferably spring). Use fire trucks to wash down and remove salt, because salt readily deteriorates concrete and corrodes steel. This activity provides you with the most benefit — at the least cost — and provides an opportunity to check the condition of the structure for needed repairs.

Erosion

Check under and around abutments to spot eroded areas (the best time to do this is when water is at its lowest in late summer). Add stone protection (rip rap) to stabilize eroded areas and provide bridge support. Remove excess winter sand from approaches to allow runoff to flow into the ditches instead of onto the bridge.

Wood Decks

Check planks for breaks, rotting, excessive wear and looseness. Replace damaged planks (“piecing in” is not recommended), re-nail planks to beams, add a waterproofing layer (tarpaper) between the beams and planks and treat with a preservative when dry.

Concrete Decks

Look for signs of leakage, cracks and rust stains from underneath. Don’t pave over concrete decks (this accelerates concrete deterioration). Every two years coat exposed concrete decks with a sealer. Sealing should be done yearly for the first two years for new concrete.

Steel Beams

Remove all dirt and/or debris yearly and paint beams, as needed, to prevent corrosion. Complete painting is usually needed every 10-20 years with occasional touch-up painting in between. Touch-up painting mainly involves the beam ends and bearings.

Timber Beams

Check for deterioration. Test with a hammer and/or occasionally drill holes to sample the interior condition. Holes must be filled in after drilling to prevent further decay.

Abutments and Piers

Check for movement and stability. Look for cracks, movement of rocks, leaning or bulging, scour and undermining. Cut and remove all brush and trees growing close to the abutments to improve air flow and limit potential damage. Repair any damaged or missing stones or concrete. Remove debris that can potentially plug bridge openings from the upstream channel.

Guardrails

If none exist, install something sturdy. If wood or steel rails (or wire cables) are bent, broken, or in poor condition, replace or reinforce deteriorated parts.

Bridge Approaches

Trim all trees and bushes to create adequate sight distance, especially around signs. Fill all ruts and eroded areas. Check for a smooth transition from the road onto the bridge. Vehicles ramping and landing on a bridge deck can cause a force equal to double their weight.

Signs

Inspect, straighten and clean warning signs. If necessary, erect new signs (both at and in advance of the structure). Two conditions require additional signage — weight posting and overpass clearances of less than 14’6”. All signs must meet MUTCD standards. Remove any brush that is obstructing warning signs.

Bearing Devices

Identify all fixed and moveable bearing devices. Clear any obstructions that would prevent a moveable support from functioning.

Cracks

Measure and keep a record of any cracks in — or movement of — the abutment main wall and wing walls.

Remember to take care of your bridges now, before it’s too late!

Source: http://baystateroads.eot.state.ma.us/newsletters/545e2744a412f971a92ac738adf955c7.pdf