Category:128 Conceptual Studies: Difference between revisions

128.1 Purpose

A conceptual study is used to coordinate MoDOT thinking on the improvements to be included in a project and to obtain approval of them as required. A conceptual study report is prepared for relatively small projects that provide specific improvements. The approved study is then used as the basis for further design. The format of the study is dependent on the proposed improvements.

A conceptual study consists of a written report that is presented in one of three formats. The basic format is used for projects containing geometric improvements. There are also two specialized report formats for projects that primarily consist of improvements to the driving surface and shoulders, with limited geometric improvements. These reports are the 3R conceptual study report (for resurfacing, restoration or rehabilitation of non-freeway roadways) and the 4R conceptual study report (for resurfacing, restoration, rehabilitation or reconstruction of interstate or freeway roadways).

As each project is developed, a conceptual study or a location/environmental study is required to document the direction that the core team is taking to address the identified transportation need. A conceptual study will provide sufficient documentation for the types of projects described below. However, more complex projects or those with a potential for greater environmental impacts will require the preparation of a location/environmental study. The details for preparing a Location Study and Alternative Analysis are available. In any case, each project that is developed requires the preparation of one of these types of report.

128.2 Conceptual Study Report

The district prepares a conceptual study report, using the necessary format, for the following types of projects:

Relatively small projects that provide specific improvements (i.e. signalization, lighting, signing, minor geometric revisions, etc.).

Bridge replacement projects on rural low volume roads where it is obvious the only practical new location is at the existing location or adjacent to the existing corridor.

Projects environmentally classified as categorical exclusions (CE).

Projects pending classification as a categorical exclusion (CE2) must have the justification approved by FHWA, which results in a CE determination, prior to preparation of the conceptual study report. A CE2 form is available. (If the CE2 is determined by FHWA to be an EA, a Location Study and Alternative Analysis is required.)

For signalization projects, the conceptual study and preliminary signal layout may be combined in one submittal. Likewise, projects that provide preventative maintenance treatments or contracted level course applications to the pavement may only require the preparation of a combined conceptual study and preliminary plans.

There may be some CE or CE2 projects for which it is advisable to prepare a location study report rather than a conceptual study report. This should be considered in the case of a highly controversial project, or one in which two or more alternatives are being considered that would have different impacts on the community, such as locating an interchange. In this case, for a CE2 project, the location study is prepared concurrently with the CE2 form to aid in FHWA determination for a CE or an EA classification.

Approximately 2 months prior to preparing a conceptual study report, the district sends two copies of a written request for environmental services (RES) to Design requesting project screening and early constraint identification. Preliminary screening may have been completed in order to obtain a CE classification from a CE2; however, it is necessary to request more detailed screening to complete the conceptual study report.

The conceptual study report describes the project purpose and identified need as well as the location and proposed improvements. The conceptual study report identifies the existing and proposed features of the project. It also explains any variations from the originally identified need.

Most generally a conceptual study report will be used to describe a simple bridge replacement project or other minor road construction project. In a few instances, a project that uses a conceptual study report format will have alternates being considered. In this case, all alternates considered should be documented in the conceptual study report in a manner similar to a location study report.

Accident data, safety enhancements, access management, how traffic will be handled during construction and the need for construction incentives are all discussed in the report. The accident data is obtained from the Transportation Management System (TMS). The calculation for the project accident rate is included. The designer carefully analyzes accident data. Any unusual circumstances are noted and recommendations for correction are proposed. Safety enhancements such as guardrail or bridge modification, access management, and the need for bicycle/pedestrian facilities are also discussed.

The conceptual study report will also discuss the disposition of the existing route. This discussion will document the anticipated disposition of all sections of the existing route in a manner similar to a location study report. A description of the available options for disposition is listed in 236.14 Change in Route Status Report.

All environmental work completed prior to the conceptual study report is summarized and included in the conceptual study report. The conceptual study report then discusses any unusual features or anticipated difficulties to be encountered with the project, such as known archaeological sites, historic bridges, wetlands, Section 4(f) or Section 6(f) lands, hazardous waste sites, or other environmental issues as provided by the Design Division.

The conceptual study report will contain a current estimate of the proposed costs of the improvements for each alternative. Details on the preparation of project estimates can be found in 104.7 Estimates. Current cost estimates, borrow information when required, and any other pertinent information to the project that is not covered elsewhere are also provided under the remarks section of the report.

A location sketch, plan sheet drawings, existing and proposed typical sections and other documents as necessary, are attached to show each alternative for the proposed improvement.

Following the signature of the preparer, a section is included for the recommendations or comments of the district engineer. If necessary to add more detail, the district engineer's comments may be submitted with a separate letter. Following that, signature and date lines are included to indicate the district engineer's approval of the study.

Preferred design criteria are contained in

230.1 Horizontal Alignment,

230.2 Vertical Alignment,

231 Typical Section Elements for Roadways,

232 Facility Selection,

233 At-Grade Intersections,

234 Interchanges,

236.13 Designing for Right of Way, and

748 Hydraulics and Drainage.

Justification for varying from these standards must be submitted on a Design Exception Information Form.

Approval and submittal of the conceptual study report is detailed in 128.10.

128.3 Pavement Rehabilitation Projects – Non - Freeway Roadways

The district prepares a 3R Conceptual Study Report for all Resurfacing, Restoration and Rehabilitation (3R) projects on non-freeway roadways. All 3R projects are designed to certain design criteria for rural and urban highways. These design criteria are only to be used for 3R projects. The values for urban highways apply to any portion of a 3R project located within the limits of a city or town. Justification for varying from these criteria must be submitted as a 131.4 Design Exception.

Approval and submittal of the 3R conceptual study report are detailed in 128.10.

128.3.1 Project Information

Any deficiencies, in addition to those included in the originally identified need, that require correction will be explained in the letter of transmittal.

128.3.2 Traffic Data

The designer requests traffic data from Transportation Planning or the TMS database.

128.3.3 Pavement Data

Part I of the 3R Conceptual Study Report shall be submitted to Construction and Materials at an appropriate time that will allow 4 to 6 weeks for a pavement evaluation to be completed and the appropriate pavement solution(s) returned to the district. The Contruction and Materials pavement section will provide the district with practical rehabilition option(s) or the district may recommend a rehabilition option and submit it to the Construction and Materials Division pavement section for approval.

If the district elects to recommend a rehabilition option to Constrution and Materials pavement section for approval, then the Strategic Highway Research Program manual (publication FHWA-RD-03-031) titled "Distress Identifications Manual for the Long-Term Pavement Performance Project" is used to describe the pavement distress. The pavement distress type and severity is documented. Any drainage issues are also documented. The amount of pavement repair is also estimated and included in the submittal.

If the distresses are such that the district is considering reconstruction for a given project, then Part I of the 4R Conceptual Study Report is also submitted to the Constructiion and Materials Division. However, a straight-line profile of the existing pavement for each direction of roadway is not required. The designer should allow 4 to 6 weeks for the evaluation to be completed and recommendations to be returned to the district.

The requirements of project scoping (104 Scope) cause identification of needs and the development of solutions to occur early in the project development process. Because of the time delay between scoping a project and actual construction, significant changes to pavement condition including accelerated pavement deterioration may occur which can make the original scoped pavement rehabilition strategy inappropriate.

For these reasons, the original pavement rehabilitation strategy, provided with the 3R report, is reviewed once the construction dollars for the project fall within one or two fiscal years beyond the current year of the STIP. Any significant changes in the pavement condition or other project data will be evaluated. The purpose of this review will be to ensure that the correct rehabilitation strategy is being used to address the pavement deficiency. This re-evaluation is conducted in a time frame that will allow any necessary adjustments to the estimated cost to occur prior to the inclusion of the construction funds in the current year of the STIP.

Should there be a need to change the recommended strategy, an approval process similar to that for the original 3R report will need to be followed for the revised strategy.

128.3.4 Geometric Data

The horizontal alignment, vertical alignment, and other features of the highway section are compared to adjoining sections. Any items within the clear zone are listed. A design exception, if necessary, is prepared and submitted for approval that reflects the minimum distance to objects in the clear zone.

128.3.5 Accident Data, Safety Enhancements, and Access Management

The accident data is obtained from the TMS database. The calculation for the project accident rate is shown in 128.5. The designer carefully analyzes the accident data. Any unusual circumstances are noted and recommendations for correction are proposed. Safety enhancements such as guardrail or bridge modification, management of access, and the need for bicycle/pedestrian facilities are also discussed.

128.3.6 Construction Sequence, Traffic Control, and Construction Incentives

The 3R report will contain a discussion of how the construction of the improvement will affect the existing traffic and any recommendations for the construction sequence that will minimize those impacts. A discussion of the traffic control that will be used during construction and the necessity for any construction incentives to shorten the time that normal traffic flow is disrupted is also included in the report.

128.3.7 Project Cost Data

The 3R report contains a current estimate of the proposed costs of the improvements. Details on the preparation of project estimates can be found in 104 Scope.

128.4 Pavement Rehabilitation Projects for Freeways

The district prepares a 4R Conceptual Study Report for all resurfacing, restoration, rehabilitation and reconstruction (4R) projects on interstates and freeways. Part I of the 4R Report is also needed for a pavement design thickness determination for any major route in which full depth reconstruction is being consdiered. Part I of the form is completed and submitted to the Construction and Materials Division, with a copy to the Design Division, in order to initiate the pavement rehabilitation analysis or pavement thickness dtermination.

Construction and Materials will issue a Pavement Type Selection (PTS) letter to the district and provide a copy to Design. Upon receipt of the PTS letter, the district will complete Part II of the form. The district will prepare an estimate of the paving and non-paving costs for each alternate provided in the PTS letter. The completed 4R report (Parts I and II) is submitted to the Design Division, with a copy to the Construction and Materials Division.

The submittal of the 4R report to the Design Division is accompanied, if necessary, by a request for any design exceptions that may be required for the project. All 4R projects are designed to current interstate design criteria (since the "4th R" stands for "reconstruction"). These criteria are found in the following locations.

230.1 Horizontal Alignment

230.2 Vertical Alignment

231 Typical Section Elements for Roadways

232 Facility Selection

233 At – Grade Intersections

234 Interchanges

236.13 Designing Right of Way Plans

748 Hydraulics and Drainage (for Bridge and Drainage issues)

Justification for varying from these criteria must be submitted as a design exception.

All "non-exempt" projects require federal oversight and require the approval of the conceptual study report by the FHWA. After review of the information and approval of the requested design exceptions by the State Design Engineer, the Design Division will submit Parts I and II of the 4R report, the rehabilitation analysis, and all costs (paving and non-paving) to FHWA for approval. Upon approval by FHWA, the Design Division will send copies of the approval letter to the district and Construction and Materials by the Design Division along with copies of the approved documents.

Design exceptions for non-exempt projects will also require approval of FHWA. Once approved by the State Design Engineer, the design liaison engineer will submit all design exceptions to FHWA for approval. After FHWA approval, the Design Division will forward a copy of the approved design exception to the district.

The requirements of 104 Scope cause identification of needs and the development of solutions to occur early in the project development process. Because of the time delay between scoping of a project and actual construction, significant changes to the pavement condition including accelerated pavement deterioration may occur which can make the original scoped pavement rehabilition strategy inapproporiate.

For these reasons, Construction and Materials is asked to review the original pavement rehabilitation strategy, provided with the 4R report, once the construction dollars for the project fall within one or two fiscal years beyond the current year of the STIP. Any significant changes in project data or pavement condition is also provided. The purpose of this review will be to ensure that the correct rehabilitation strategy is being used to address the pavement deficiency. This re-evaluation is conducted in a time frame that will allow any necessary adjustments to the estimated cost to occur prior to the inclusion of the construction funds in the current year of the STIP.

Should there be a need to change the recommended strategy, an approval process similar to that for the original 4R report will need to be followed for the revised strategy. This may include re-submission to the FHWA, if applicable

128.4.1 Project Information

Any deficiencies, in addition to those included in the originally identified need, that require correction are explained in the letter of transmittal.

128.4.2 Traffic Data

The designer requests traffic data from Transportation Planning or the TMS database

128.4.3 Existing Pavement Data

If the district elects to recommend a rehabilition option to Construction and Materials for approval, then the Strategic Highway Research Program manual (publication FHWA-RD-03-031) titled "Distress Identifications Manual for the Long-Term Pavement Performance Project" is used to describe the pavement distress. The pavement distress type and severity is documented. Any drainage issues are also documented. The amount of pavement repair is also estimated and included in the submittal.

Any items that might restrict the addition of pavement thickness to the existing traveled way are noted. These might include drainage structures, curbing, median barriers, right of way restrictions, or other special conditions.

The straight line profile identifies the location of all bridges, including overpasses, by log mile and station, and indicates at each location the field measured vertical clearances. It also states if the bridge is to be used in place, rehabilitated or reconstructed. An example of a sketch showing existing lanes, additional lanes proposed under the project, and additional lanes programmed in the future is available. The width of the median and location of existing bridges, including overpasses, is also shown on this sketch. The location of each item is identified by log mile.

128.4.4 Proposed Pavement Data

The district submits proposed pavement data after the Construction and Materials Division has determined the rehabilitation method. If the district’s proposed pavement rehabilitation method is different than the one recommended by the Construction and Materials Division, justification must be provided.

128.4.5 Geometric Data

The horizontal alignment, vertical alignment, and other features of the highway section are compared to adjoining sections. Any items within the clear zone are listed. A design exception, if necessary, is prepared and submitted for approval that reflects the minimum distance to objects in the clear zone.

128.4.6 Crash Data and Safety Enhancements

The crash data is obtained from the TMS database. The calculation for the project crash rate is shown in 128.5. The crash data included in Part II is used to determine whether a special surface needs to be applied to reduce the accident rate. The designer carefully analyzes the crash data. Any unusual circumstances are noted and recommendations for correction made. Safety enhancements such as guardrail or bridge modification, and the need for bicycle/pedestrian facilities are also discussed.

128.4.7 Construction Sequence, Traffic Control, and Construction Incentives

The 4R report will contain a discussion of how the construction of the improvement will affect the existing traffic and any recommendations for the construction sequence that will minimize those impacts. A discussion of the traffic control that will be used during construction and the necessity for any construction incentives to shorten the time that normal traffic flow is disrupted is also included in the report.

128.4.8 Project Cost Data

The 4R report contains a current estimate of the proposed costs of the improvements. Details on the preparation of project estimates can be found in 104 Scope.

128.5 Crash Rate Calculation

A crash rate is calculated for each project and included in the conceptual study.

The formulas for the crash rates are:

Segment Crash Rate

${\displaystyle {\mbox{Segment Crash Rate}}={\frac {\mbox{no. of crashes x 100,000,000}}{\mbox{no. of yrs. x 365 x weighted ave. AADT x length in miles}}}}$

The segment crash rate yields a result in crashes per hundred million vehicle miles traveled (HMVMT). The number of crashes is the total number of crashes in the study period. For conceptual reports a five-year study period is typically used, utilizing the last five full years of traffic crashes. The AADT and crash data are obtained from the TMS database maintained by Transportation Planning. The calculated crash rate is compared to the five-year average statewide rate for a similar class of highway as obtained from Transportation Planning or found in their Traffic Crash Statistics.

Intersection Crash Rate

${\displaystyle {\mbox{Intersection Crash Rate}}={\frac {\mbox{No. of crashes x 1,000,000}}{\mbox{No. of years x 365 x Entering AADT}}}}$

The intersection crash rate yields a result in crashes per million entering vehicles. Entering AADT includes all legs of the intersection. The number of crashes is the total number of crashes in the study period. For conceptual reports a five-year study period is typically used, utilizing the last five full years of traffic crashes. The AADT and crash data are obtained from the TMS database maintained by Transportation Planning. The calculated crash rate is compared to the five-year average statewide rate for a similar class of highway as obtained from Transportation Planning or found in their Traffic Crash Statistics.

128.6 Basic Lighting

Basic lighting is provided along the major road at any interchange within the limits of a 3R or 4R project that meets the warrants given in 901 Lighting. If warranted, basic lighting is shown as part of the scope of the project.

128.7 Guardrail

Criteria for upgrading guardrail are given in 606.1 Guardrail.

128.8 Logical Termini

All 3R and 4R projects must have logical termini.

128.9 Documentation of Design Exceptions

Documentation of design exceptions is necessary for the department to be able to defend itself from litigation. Litigation may take place many years after the actual construction and permanent documentation is necessary to determine the justification for design exceptions.

Design exceptions consist of items that vary from published MoDOT design criteria. In most cases the need for design exceptions are the result of the inability to reasonably meet the preferred design criteria specified in this document. However, there are occasions where the improvements will greatly exceed the normal criteria recommended for the type of improvement. These variations must also be documented through the design exception process. When there is doubt if a design exception is required, the design liaison engineer should be consulted.

The preferred design criteria for new construction on rural and urban highways, 3R and 4R projects are available in various locations.

230.1 Horizontal Alignment,

230.2 Vertical Alignment,

231 Typical Section Elements for Roadways,

232 Facility Selection,

233 At-Grade Intersections,

234 Interchanges,

236.13 Designing for Right of Way, and

748 Hydraulics and Drainage.

The criteria for proper access management can be found in MoDOT’s Access Management Guidelines. On urban projects, turning lane width and whether the pavement is curbed or uncurbed are noted on this form. A Design Exception Information form is not required if all established design criteria are used.

128.10 Conceptual Study Report Approval and Submittal

The district engineer has the authority to approve all project specific details for projects that meet the requirements to use a conceptual study report, 3R conceptual study report or 4R conceptual study report. For projects requiring a location study/environmental report, the approval and submittal requirements are described in Section 127. This approval by the district engineer is contingent upon the approval of any design exceptions by the State Design Engineer or approval by the FHWA.

All "non-exempt" projects (interstate, major bridge or certain special projects) require federal oversight and require the additional approval of the conceptual study report by the FHWA. For these projects, the conceptual study report, regardless of the format, and any requested design exceptions are submitted to FHWA.

The submittal of a 4R conceptual report to FHWA is a specialized case. All other conceptual study reports are submitted to Design. Design, upon approval of the design exceptions by the State Design Engineer, will send a transmittal letter and necessary information to FHWA for review and approval. Upon receipt of FHWA approval, the Design Division will inform the district to proceed with the design of the project and forward a copy of the approval action and signed design exceptions.

"Exempt" projects (all other projects) do not require direct federal oversight and will therefore not be submitted to FHWA for approval. The district engineer may approve the conceptual study report, 3R conceptual study report, or 4R conceptual study report for these projects. A copy of these reports is forwarded to Design. For those projects where a design exception is required the district engineer’s approval is also necessary. The district must submit a copy of the approved design exception to Design. Once the design exception is approved, the district has authority to proceed with the design of the project.

In both of these situations, the district will provide Design and Construction and Materials a copy of the approved conceptual study report.

128.11 Airports

If a highway improvement is located within 2 miles (3 km) of an existing airport, a letter is submitted to the Design Division as directed in 235.8 Preliminary Plans.

The notice and submittal requirements of Federal Aviation Regulation Part 77 shall be followed if any highway improvement is located near an airport. Notice criteria can be found online at http://www.faa.gov/airports_airtraffic/airports/regional_guidance/central/construction/part77/#who. Highway improvements located near airports shall also be coordinated with the Aviation Section in Multimodal Operations. The airspace filings can be submitted electronically through FAA’s website at https://oeaaa.faa.gov/oeaaaEXT/portal.jsp.

Particular attention is given to all types of signs, light poles, cranes, and large equipment that may require notice as outlined in F.A.R. Part 77. The names and locations of civil and private airports in Missouri can be obtained from the "Missouri Aeronautical Chart" available from the Aviation Section in Multimodal Operations.

128.12 SEMA Flood Buyout Program

The State Emergency Management Agency (SEMA) has the ability to place permanent deed restrictions on lands located in floodplains. These restrictions require open space land usage only, no structures, roadways or fills are allowed. If a project encroaches on any deed restricted lands, an official with the city or county must be contacted to identify the exact location of the deed-restricted properties.

128.13 Draft Project Scoping Documentation for System Expansion Projects

The project manager completes the draft project scoping documentation following approval of the conceptual plan for Major Projects. The details of the documentation are found in 104 Scope.