Mon-Fayette Transportation Project - Sections 52D & 52F2
Harrisburg, PA

DMJM+HARRIS has completed preliminary engineering for a new eight-kilometer (five-mile) segment of the Mon-Fayette Expressway Project in Washington County, PA. Additionally, DMJM+HARRIS is completing final design plans for 3.7 kilometers (2.3 miles) of this new four lane divided roadway. Key features of this project include a diamond interchange with ramp toll plazas and interchange lighting and the design of eight new structures, which range in length from 51 to 396 meters (170 to 1300 feet) and in height from 15 to 34 meters (50 to 110 feet)

Among these structures are two twin mainline bridges crossing streams and local roads. The first structure is a seven-span continuous welded, steel plate girder with a length of 396 meters (1300 feet). The other is a 274 meter (900 feet) curved steel plate girder consisting of five continuous spans. Superstructure design for both bridges was performed using BSDI, a three-dimensional finite element software package. Single column flared concrete piers comprise the substructure of these long span bridges. The piers were designed with additional seat width to accommodate an extra girder line for future deck replacement or possible widening. The foundation design incorporated the use of soil grouting measures to stabilize the numerous mine shafts in the vicinity of the structures.

In addition to the bridge structures required by the new alignment, DMJM+HARRIS’ engineers also designed two cast-in-place box culverts. A 28-meter (90-foot) culvert will employ staged construction methods and a temporary stream diversion while the 171-meter (560-foot) culvert will support the mainline and 19 meters (62 feet) of fill.

The roadway design has been complicated by the need to negotiate a myriad of issues with the owner of a coal refuse storage site along the proposed alignment. DMJM+HARRIS has been instrumental in these negotiations. By careful consideration of the needs of both the Pennsylvania Turnpike Commission and the mine, DMJM+HARRIS has created a plan that optimizes the requirements of both parties. Examples of this include allowing the mine operations to place coal refuse against the expressway embankment slopes thereby expanding the mine’s storage capacity; placing a dam, which separates the expressway from the mine’s slurry pond, at a location that maximizes the pond’s capacity and hence minimizes the amount of compensation due the mine’s owner; and redesign of the environmental impact statement for mine access roads concepts which reduced the project cost by approximately $6,000,000 and also allows for future recreational use of the refuse site after it is capped and reclaimed.

Other aspects of the project include the design of eight storm water retention basins to minimize impacts to the existing water shed, final right-of-way acquisition plans involving 35 property owners, approximately 98 hectares (246 acres), and both surface and subsurface coal rights, and erosion and sedimentation control plans.