Alternate Pavement

Examples and Results

Request for Bids

Pavement Plans

January 2007 Bid Results

Overall Bid Results

Purpose of Alternate Pavement Bidding

In an effort to get the best value, create a competitive environment for concrete and asphalt paving industries and promote innovation, MoDOT requires alternate pavement options in the majority of contracts containing full depth pavement. When alternate pavements are bid, then it is necessary to calculate a Life-Cycle Cost Adjustment (LCCA) factor. Future maintenance costs are considered in determining the LCCA factor, thus resulting in the most equivalent specifications possible to draw in the maximum number of bidders for MoDOT paving projects. While alternate bidding is generally advantageous for all projects, circumstances occasionally arise which cause one pavement type to be preferred over the other (See Specifying One Pavement Type).

Life-Cycle Cost Adjustment (LCCA)

Area of pavement is used to determine whether an alternate pavement project qualifies for a life cycle cost adjustment factor as calculated by the Design Division or a $0 life cycle cost adjustment factor (see Alternate Categories).

The LCCA is a monetary value calculated for each group of alternates in a project and provides a way to fairly compare bids received for low bid and possible contract award. The value considers future treatments that are routinely applied to concrete and asphalt pavements. Treatments considered for asphalt pavements are cold milling and overlay of the traveled way only at 20 years and of the entire surface at 33 years. Treatments considered for PCCP are pavement repair and diamond grinding of the traveled way at 25 years. The treatment types and timeframes used for calculating the LCCA were jointly agreed upon between MoDOT and contracting industries.

The following examples shows how the LCCA is applied to a full asphalt option and a concrete mainline with asphalt shoulder option:

Note that no LCCA is applied to concrete shoulders.

MoDOT’s estimators prepare LCCA factors for inclusion in the contracts' Job Special Provisions for projects containing alternate pavements. The latest published real interest rates from the United States Office of Management and Budget will be used to bring the future costs to present worth.

Two separate LCCA factors will be calculated for the contract, one for the mainline pavement and one for the shoulder pavement (A2 or thicker). This will allow contractors flexibility in bidding thus enabling use of the best valued material for the regional market. Projects with alternate pavements will include a life cycle cost adjustment factor as calculated by the Design Division or a $0 life cycle cost adjustment factor according to the following table:

Alternate Categories

While each project has the possibility of differing slightly from any other project, there are some general guidelines to consider when setting up alternate categories.

The following parameters dictate whether Alternate Pavements are to be set up for a project. Alternates pavements are used according to the criteria in the following table:

Use of Life Cycle Cost Adjustment Factor for Alternate Pavements

Area of Pavement* and Shoulder** > 14,000 yd2 total	Area of Pavement and Shoulder** < 14,000 yd2 total
	> 7,500 yd2 Continuous	< 7,500 yd2 Continuous
Use LCCA	Use LCCA	No LCCA
* Different pavement surface types (high vs. low) are to be considered when computing the area; pavement thickness may vary. Superpave is a High Type Asphalt Mix. Bituminous Pavement is a Low Type Asphalt Mix. (Total area of High Type Asphalt Mix Surfaces > 14,000 yd2 OR Total area of Low Type Asphalt Mix Surfaces > 14,000 yd2)
**Includes A2 (5 3/4 in.) or thicker shoulders

Additional consideration is needed for some contracts with projects in combination. If the projects are disconnected (separated by relatively large distances) then each project’s pavement areas should be accounted for by project. If, however, the projects in combination are continuous, in the same area, or in relatively close vicinity of one another, the pavement areas should be considered by contract when determining if alternate pavements should be used.

When alternate pavements are required, the project should be evaluated to determine how to set up the alternate paving categories.

• Areas with different surface mix types (SP or BP) should be in separate alternates. The binder type/grade is not considered in alternate category determination, however it is taken into account in cost calculations for the LCCA. An example of this is when the mainline pavement is a SP125 mixture and the outer roads are BP-1.

• Ramps should be placed with the highest priority route or with like surface type (SP or BP).

• Shoulders - If it has been determined that alternate pavement is required on the project then the A2 shoulders should be a separate group of alternates. A3 shoulders are not considered for LCCA’s and should be placed in the roadway category.)

Information Required for Completion of LCCA

Since LCCAs are based on future treatments, any area that will have a treatment with a different cost applied to it needs to be broken out as a separate quantity. Therefore, areas submitted should be broken down based on surface mix with consideration of mix design and of binder type (i.e., SP125 vs. BP-1 or SP125C, PG64-22 vs. SP125C, PG76-22 or SP125BSMR vs. SP125B). The following information is necessary:

1) Area of Traveled Way (See examples for details on the areas that are considered/required) - consists of the area within the travel lane (pavement markings) for each set of alternates (per mix design and binder grade).

2) Total Area of Pavement – Needed for each set of alternates and can usually be obtained from a project’s plans Quantity Sheets or proposal (per mix design and binder grade).

3) Type of Asphalt Pavement Surface Mix (mix design and binder grade).

One quick check for the correctness of the traveled way submission is that it should theoretically be less than the pay item quantity.

Time Frame for LCCA Completion

Districts need to supply the information required for completion of the LCCA factors in the transmittal memorandum that is included with the PS&E submittal by the PS&E due date. This will allow time for the Design Division reviewer to check the submittal, send any review comments as necessary and forward a request to the estimator within the time allotted.

To ensure there is sufficient time to prepare an accurate LCCA by the due date, a request for LCCA should be submitted to the estimators a minimum of one week before the notice with all the required information. This will allow time to receive material quotes, which may take a few days to receive, and prioritize the request among estimating projects in the current letting.

Plans For Projects with Alternate Pavements

Plans for all projects with alternate pavements should contain:

• Typical sections for both alternates, including station limits, and all side road connections.
• All pay items for full depth alternate pavements shall be in square yards for the entire pavement surface.
• One set of 2B sheets with separate sheets for the items associated with each alternate.
• Using the "Estimate 2000" program, the quantities for pavement and other items associated only with the asphalt alternate (designated as "Alternate A") should be designated as "Section 02" and the quantities for pavement and other items associated only with the concrete alternate (designated as "Alternate B") should be designated "Section 03". For A2 shoulders or thicker use "Section 04" for the shoulder type that corresponds with "Section 02" and "Section 05" for the shoulder type that corresponds with "Section 03". This will enable summation of the appropriate subtotals to compile an estimated total cost per alternate.
• No pay item listed in Section 02 or 03 should be listed in Section 01. This would lead to differing bids and cause confusion when administering the contract. For example, if the base quantities differ, include the appropriate total base quantities in Sections 02 and 03, but not Section 01.
• For shoulder rumble strips, include the bituminous rumble strip pay item with the asphalt alternate, and the concrete rumble strip pay item with the concrete alternate.
• Job Special Provision ALTERNATE FOR PAVEMENTS JSP-96-04 should be inserted in the Job Special Provisions. The Life Cycle Cost adjustment factor is calculated by the Central Office.

Below are design guidelines for different project scenarios:

Separate Grading and Paving Projects with 18 in. Rock Base

• Subgrade profile and cross sections should be designed for the thicker pavement alternate.
• If the thinner option is constructed, the contractor will be responsible for maintaining the profile grade. In the paving project the addition of subgrade material for the thinner pavement design will be paid for as Subgrading and Shouldering, Class 2.

Separate Grading and Paving Projects without 18 in. Rock Base

• Subgrade, profile and cross sections should be designed for the thinner pavement alternate.
• If the thicker option is constructed the contractor will be responsible for maintaining the profile grade. In the paving project the removal of subgrade material for the thicker pavement design will be paid for as Subgrading and Shouldering, Class 1.
• Crossroad structures should be designed to accommodate a minimum cover based on the thicker pavement design.

Combined Grading and Paving Project

• Subgrade profile and cross sections should be designed for the thinner pavement alternate.
• The contractor will be responsible for maintaining the profile grade for either alternate pavement with no direct pay.
• Crossroad structures should be designed to accommodate a minimum cover based on the thicker pavement design.

Specifying One Pavement Type

The core team should always look at pavement options that bring the best value to the project. Consideration should be given to initial construction cost, long-term maintenance cost, and continuity with existing pavement. Also, impacts to local residents and businesses along the route should be considered.

Pavements having prevailing issues that make only one type of pavement desirable should be examined to determine the feasibility of alternate bids on pavement. These may include circumstances such as widening existing pavements with safety and durability issues due to differing pavement types in the driving lanes, urban construction, consideration of how the pavement type effects the major item of work for the project (e.g., if major item of work for the project is bridge work the life cycle costs may be insignificant to the total project cost), total amount of paving compared to existing pavement, project staging and project scoping with regard to long-range transportation goals.

In unique circumstances, the core team may determine there is a need to specify one pavement type over another on a project. The core team decision, which will include the concurrence of the Pavement Team member and the Design Liaison Engineer, is documented through the Design Exception process.