Project Overview

Location: North Mississippi Street & East Cayuga Street, Saint Paul, MN

Client: Summit Envirosolutions

Constructed: ca. 1912

Project Date: 2013

Project Scope: Historic Structure Documentation

Preservation Design Works (PVN) was retained in the summer of 2013 as a sub-consultant to Summit Envirosolutions to assist with the documentation of the Minnesota Department of Transportation’s (MnDOT) Bridge 92297 for the Minnesota Historic Properties Record (MHPR). Bridge 92297 was a single-span reinforced concrete flat slab bridge formerly located on Mississippi Street adjacent to Cayuga Avenue in Saint Paul. The bridge was constructed by the Minneapolis, St. Paul and Sault Ste. Marie Railway Company (Soo Line) circa 1912 as an overpass to carry vehicles, pedestrians, and a streetcar line over a railroad corridor. Original construction drawings indicated the bridge was designed by C.A.P. Turner, a nationally prominent engineer based in Minneapolis.

Documentation of the bridge for the MHPR was prompted by realignment plans for the adjacent Interstate Highway 35E that necessitated the demolition of the bridge. For this project, PVN provided expertise in the assessment and documentation of the bridge’s structural design. The scope of work included an evaluation the condition of the bridge prior to demolition, an assessment of its construction methods and materials, and documentation of the configuration of the bridge’s reinforcement which was achieved by meticulous selective demolition of the concrete, and a comparative analysis between the design of the bridge shown in original drawings with the bridge as constructed. Deliverables included a written report of our observations and analysis, as well as measured drawings of the steel reinforcement used in the bridge.

When demolition of a resource is unavoidable, documentation can partially mitigate this loss by recording and allowing for the future study of the resource’s features. PVN is uniquely positioned to bring added value to documentation projects, as our interdisciplinary staff combines historical consultants and researchers, historical architects, and expertise in city planning, structural engineering, and construction history.

Photo credit: Dan Pratt, ARCH3, LLC