The sidewalk improvements along Portola Avenue, just west of Egan Junior High School, consist of a 640 LF section of roadway that has no sidewalk. This route is a popular section of roadway which is frequently used by students. Due to the lack of sidewalks, the students are forced to walk on or near the street which creates a dangerous situation; in addition, the drainage is poor which causes ponding and slip hazards. The project consists of installing a new curb, gutter, and sidewalks along the roadway that will ultimately connect to the existing sidewalk at each end of the section. The project also involves reconstruction of portions of the street to make gutter slopes work effectively.
In order to minimize pavement work and reduce budget, Siegfried employed a design technique called the Envelope Method where the maximum and minimum acceptable slopes from the adjacent lot to the top of curb is determined. The area between the two profile lines represents the “envelope” of top of curb design grades which will assure positive drainage as well as visually pleasing slopes to transition points. It is our experience that the Envelope Method is a proven method which reliably reduces design time and design grade errors due to manual calculations and data entry.