This project provides for the replacement of the existing Parklawn Entrance Bridge over Rock Creek in Rockville. The existing bridge, built in 1950, is an approximately 42.5' long single span structure with four rolled steel beams and a timber deck supported by concrete cantilever abutments and concrete wingwalls. It provides a 10'-6" wide clear roadway to accommodate both the Rock Creek Trail and a single lane for two-way vehicular traffic on Parklawn Entrance. It provides the only access to a resident property and the Parklawn community garden. The proposed replacement bridge will be a 50' span prestressed concrete adjacent solid slab structure with a concrete overlay. It will carry a single 10' wide vehicular lane for two-way traffic, along with a 2' wide striped buffer zone with a flexible longitudinal separator and a 10' wide shared use path to accommodate pedestrians and cyclists using the Rock Creek Trail. The proposed bridge will be constructed on a new alignment and will require relocation of both Parklawn Entrance and Rock Creek Trail within the vicinity of the bridge. The relocated portions of Parklawn Entrance and Rock Creek Trail will feature a raised profile compared to the existing ground. This new alignment will allow the existing bridge to remain open and accessible to vehicles, pedestrians and cyclists during construction. A temporary trail alignment will be required both east and west of the proposed bridge. The project scope also includes installation of stream restoration structures to provide grade control and stream stabilization at the location of the replacement structure and around the upstream bend. Accelerated bridge construction techniques (ABC) will be utilized to minimize the disruption to the traveling public and local community.

The roadway Average Daily Traffic (ADT) is approximately 40 vehicles.

The proposed replacement work is necessary to provide a safe roadway condition for the travelling public. The recent Bridge Inspection Report for Bridge No. M-PK17 indicates that steel beams are in deteriorating condition. There are typically sections of up to 3/16" deep painted over pitting on the bottom of the beam web faces. The bolts connecting the bottom flange of the beams to the abutments are typically leaning at both abutments and exhibit up to 75 percent section loss. There are multiple inactive areas of 100 percent section loss in Beams 2 and 3. Several diaphragm connections at mid-span have cracks in welds between diaphragm and beam. The superstructure has been cleaned and painted, and several plating repairs have been installed. These repairs were meant to be temporary and to keep the bridge safe until the replacement design could be completed. In addition, the existing bridge railings do not meet current safety standards and erosion is occurring along the existing stream banks. The bridge is currently posted for a 14,000 lbs. limit for a single-unit truck and a 26,000 lbs. for a combination-unit truck. Implementation of this project would allow the bridge to be restored to full capacity.

The Parklawn Entrance Bridge is owned by the Maryland-National Capital Park & Planning Commission (M-NCPPC). The Bicycle Master Plan designates this segment of Rock Creek Trail - from Avery Rd to Veirs Mill Rd Trail Connector as a Stream Valley Park Trail.

The design costs for this project are covered in the Bridge Design project (CIP 509132). The costs of bridge construction and construction management for this project are eligible for up to 80 percent Federal Aid. A design exception for single lane bridge design has been received for Federal Aid funding.

A pedestrian impact analysis has been completed for this project.

Federal Highway Administration - Federal Aid Bridge Replacement and Rehabilitation Program, Maryland State Highway Administration, Maryland Department of the Environment, Maryland-National Capital Park and Planning Commission, Montgomery County Department of Permitting Services, Utilities, and Bridge Design Project CIP 509132