Home / Services / Street Improvement Plans
Street Improvement Plans
Street improvement plans function as specialized documents that focus on roadways to support the basic civil improvement package that controls the entire street area instead of controlling only the development connection points. The street improvement plans go beyond basic frontage work to develop complete roadway systems which include pavement design elements, geometric road layouts, right-of-way drainage systems, and post-construction traffic durability assessment.
Trusted By:
The difference becomes most apparent during major construction projects, which include building new subdivisions with their own road systems and expanding commercial properties that back up to main roads, and all developments for which cities need to build complete road systems instead of performing surface repairs. The street functions as an independent engineered system which receives evaluation through pavement and geometric standards that do not share common points with standard grading or drainage evaluation processes.
What street improvement plans actually cover
A complete set of street improvement plans establishes horizontal and vertical roadway alignment, showing centerline geometry, curve radii, and profile grades that meet the jurisdiction’s design speed and sight distance standards. It includes pavement section design the specific thickness and material makeup of asphalt or concrete, base and subbase layers, engineered from soil conditions and projected traffic loading rather than assumed from a generic standard detail.
It shows cross-sections at regular intervals establishing crown, cross-slope, and the full width of paving, curb, gutter, sidewalk, and any parkway or landscape strip within the right-of-way, along with street drainage design, catch basins, storm drain laterals, and gutter flow calculations sized to the roadway’s own contributing drainage area, separate from the site’s internal drainage system. Where a project affects an intersection, plans also address signal timing modifications, striping, and any required turn lanes or channelization.
For larger roadway projects, a corresponding traffic control plan is often required as a separate but related document, addressing how traffic will be maintained through each phase of construction.
Why pavement design is its own technical exercise
Unlike most of the elevations and layouts elsewhere in a civil package, pavement section design is a structural calculation, not a drafting decision. It starts with a geotechnical evaluation of the subgrade soil’s bearing capacity, combined with a projected traffic index reflecting how many vehicles and how many heavy vehicles, specifically, the street is expected to carry over its design life. Two streets that look identical on a site plan can require meaningfully different pavement sections if the soil underneath or the anticipated truck traffic differs, which is why this piece of the design typically can’t be finalized until geotechnical data for the specific alignment is available.
How this connects to the rest of the project
Street improvement plans have to tie precisely into the site’s driveway approaches, the frontage improvements shown on the broader civil improvement plans, and any utility work running beneath or along the new pavement section sewer and water laterals, storm drain connections, and dry utility conduits all need to be coordinated so they’re installed before final paving, not after. On projects building new internal streets, the improvement plans also have to reconcile with the subdivision’s grading design, since street grades constrain what’s achievable on adjacent building pads and vice versa.
Agency review in California
Street improvement plans are reviewed by a jurisdiction’s public works or engineering department against its own design standards, typically referencing a regional base standard such as the Standard Specifications for Public Works Construction with city-specific modifications for items like minimum pavement sections, curb return radii, or required street tree spacing.
Projects proposing new public streets, rather than improving an existing one, often go through an additional review layer for right-of-way dedication and acceptance, since the completed street is typically deeded to the public agency and becomes its long-term maintenance responsibility. Some cities also require a separate traffic engineering review for projects affecting intersection operations or requiring new traffic control devices.
When you need this
Any project constructing a new public street, widening or reconstructing an existing one along its frontage, or significantly modifying an intersection needs street improvement plans as part of its civil package. This is common on new subdivisions, larger commercial developments, and any project a jurisdiction requires to bring a substandard roadway up to current design standards as a condition of approval.
- Common Questions
Frequently asked questions
Street improvement plans focus specifically on the roadway as an engineered structure pavement design, geometric alignment, and street drainage while general improvement plans cover the broader frontage work, including curb, sidewalk and driveway connections. Larger roadway projects typically need both, developed together.
Standard details assume typical soil and traffic conditions. Actual pavement thickness depends on the subgrade's bearing capacity and the specific traffic loading the street will carry, both of which vary by site so many jurisdictions require a project-specific pavement design rather than accepting a generic standard section.
Often, yes, for larger projects. Traffic control plans address how traffic is maintained during construction itself, while street improvement plans show the finished, permanent roadway design. They're related but separate documents reviewed for different purposes.
On most subdivision or new-street projects, the completed roadway is dedicated to the public agency through a right-of-way dedication process and becomes the agency's long-term maintenance responsibility, which typically triggers an additional review and acceptance step beyond standard plan check.
Yes. Street grades and the site's building pad grades constrain each other, particularly on projects building new internal streets, so the two are developed together rather than independently to avoid conflicts at the point where site grading meets the roadway.
Where we start
We begin by identifying the jurisdiction’s roadway design standards and coordinating with geotechnical data to establish the pavement section, then develop the roadway geometry against the project’s grading and driveway layout. Send us the project address and site plan, and we’ll confirm the street design standards your jurisdiction will apply, along with a fee and schedule in writing.