Back of Sidewalk Profiles

I'm working on a job that's just designing new sidewalk along an existing curbed roadway as well as some drainage. We're scoped to show back of sidewalk profiles in our sheets, however I'm struggling to figure out the best method of doing this. We have limited DTM (basically just around where the sidewalk is being proposed). We're given a survey baseline which is outside of the provided DTM. What is the method of showing proposed BOS profiles and existing ground on our profile sheet? It is creating a construction alignment along the back of sidewalk? Or should I project the the BOS profile and existing ground profile on to the baseline survey? If the best option is the later, is there anyway to project both proposed and existing profiles without creating a 'dummy' existing ground smart line. 

Thanks in advance for any help. 

  • Sorry if i am telling you what you may already know. BOS profiles are typically used as a drainage design tool to show offsite flow coming onto your project which will help you in placing BOS inlets. On the profile sheets you would show existing ground cut at the BOS and then the proposed BOS profile above it. On the major grid lines, usually at the top of the sheet, you would show a flow arrow pointing in the direction of the offsite flow.

  • Gotcha, but when we create the profile sheets, we would be following a certain alignment with the projected profiles on it? I'm just trying to figure out if I need to create a CL of construction at the BOS and have station equation to equal the BL Survey. 

  • The short answer is, you can do it either way just keep in mind if you use a CL of Const that does not parallel the BOS you wont have accurate Slopes between stations as the BOS line varies, so in this case only provide spot elevations on the profile. If you create a BL along the BOS then you can provide Slopes like you are accustomed to seeing on a profile.