Study of Market Street Bridge in Harrisburg also underway

Harrisburg, PA – The Pennsylvania Department of Transportation (PennDOT) announced today that a study is underway to investigate why mayflies are attracted to the above-deck lighting on the Route 462 Veterans Memorial (Columbia-Wrightsville) Bridge, which spans the Susquehanna River and connects the Borough of Columbia and West Hempfield Township in Lancaster County and the Borough of Wrightsville in York County.

The goal of the study is to identify potential changes to the lighting that could be made in conjunction with a future bridge rehabilitation project. The bridge lighting was replaced in 2014 with historic reproduction lanterns. This had the unforeseen effect of attracting swarms of mayflies to the top of the bridge. As a result, bridge lighting is turned off during the annual mayfly season to avoid the swarming and the problems that have arisen from it. 

This study, in partnership with the local municipalities, aims to determine why mayflies are attracted to the bridge’s lights with the ultimate goal of devising a solution that may reduce the number of mayflies on the bridge. Potential solutions may include making minor changes to the lighting and/or adding lighting under the bridge. The City of Harrisburg is also a cooperative partner in the study by allowing the Market Street Bridge’s under bridge lighting colors to be varied as part of the testing to determine its attractiveness or deterrence on mayflies. Tests involve leaving the majority of lights turned off on the bridge, while three evenly-spaced groupings of lights, each consisting of four light fixtures, will remain on. The illuminated fixtures will have different colors or shades of light; and for part of the testing may be shielded to partially block the light in certain directions. Additionally, floodlight fixtures will be suspended from the edge of the bridge at select locations, to shine light underneath the bridge. Independent researchers, as part of the broader team, will analyze the collected data and develop recommendations. The anticipated testing is scheduled for the following timeline (weather dependent): • Contractor to temporarily modify light fixtures:  June 8-9, 2020 • Data collection of lighting and mayfly interaction:  June 10-24, 2020 • Contractor to return light fixtures to original set up:  June 25-26, 2020

An electrical contractor will perform the lighting modifications during the day-time hours. Motorists may experience minor delays while the work is being performed. Pedestrians should use caution along the sidewalk when passing the contractor’s vehicle. The public will be notified in advance of the testing. Message boards placed on each end of the bridge on the nights of testing will also alert motorists and pedestrians. Depending on weather and the level of mayfly activity, testing is anticipated to last up to three nights during the two-week data collection period. Workers will be on site at various times during these night-time tests to observe mayfly interaction with the lights, record light level readings, and take photographs.  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. Work on this project will be in accordance with Centers for Disease Control and state Department of Health guidance as well as a project-specific COVID-19 safety plan, which will include protocols for social distancing, use of face coverings, personal and job-site cleaning protocols, management of entries to the jobsite, and relevant training. For more information on projects occurring or being bid this year, those made possible by or accelerated by the state transportation funding plan (Act 89), or those on the department’s Four and Twelve Year Plans, visit www.projects.penndot.gov.

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MEDIA CONTACT: Dave Thompson, 717-418-5018