311 Help Desk
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City of harrisburg logo

HARRISBURG – The City of Harrisburg is a cooperative partner in a PennDOT study investigating how bridge lighting could affect mayflies in the area. The Market Street Bridge’s under bridge lighting colors will undergo adjustments as part of the testing to determine its attractiveness or deterrence on mayflies. 

This study aims to target certain characteristics of the under arch lights on the Market Street Bridge and determine whether it impacts the number of mayflies attracted to the bridge’s above deck lighting. This may ultimately include minor changes to the above bridge lighting and/or the addition of under bridge lighting based on the testing study outcome anticipated to be known in the Fall of 2020.  Workers will be on site at various times during the night-time testing period, observing the mayfly interaction with the lights, recording light level readings, and taking photographs. 

The testing will begin later this week or early next week, depending on mayfly hatch and weather conditions. There will be signage displaying alert messages on the nights of actual testing, anticipated to be up to two nights under optimal weather and mayfly conditions, during the data collection period. 

Motorists are advised to slow down and use extra caution during the testing events for their own safety and for that of PennDOT’s workers.