Traffic

The following controls, located on the Input -> Project Information Page, are used to specify the traffic loadings for the pavement project.

The first set of controls, shown below, consists of several readonly fields that are used to report Caltrans traffic counts at the center point in the project limits. They are populated by CalME once the pavement project has been located on a route.

For example, if the pavement project is located in District 1, County of Del Norte, Route 101 North, PM Start of M0.000 and PM End of R1.000, the traffic counts reported in the Traffic Count Information set of controls will be based on the PM corresponding to: (State Odometer at the PM Start + State Odometer at PM End) / 2.0.

Traffic count data items:

•Location - the location of traffic counts comes from the PaveM traffic database. The PaveM database uses a processed version of the Caltrans traffic database and the PeMS database. The processing of these two databases results in one-way traffic counts, at a section level, not at a specific point. Section limits (or break points) are determined by a combination of the Caltrans Highway Log, the Caltrans Sequence Listing and with considerations of the specific locations of traffic counts. For the sample below, the traffic counts are for a section at "R0.347" to "R0.510".

•Location Description - a description of the location, if available, e.g., "0.1 mile before Bridge #23-127865"

•AADT - Average Annual Daily Traffic (one direction, all lanes)

•AADTT - Average Annual Daily Truck Traffic (one direction, all lanes)

•% Trucks - Percent Trucks (one direction, all lanes)

The second set of traffic controls, shown below, are used to specify traffic loads in the Design lane. CalME assumes that the Design lane is the outer-most lane since that lane has most of the truck traffic. Therefore, traffic count data is distributed across the lanes of traffic based on truck lane distribution rules.

Design Lane Traffic Loads data items:

•Load Distribution (WIM Station) - CalME populates this dropdown control with the Suggested value. You may select something other than the Suggested value.

•Suggested WIM Station - this is a readonly field that CalME populates. CalME determines the Suggested WIM group using the 9-to-5-axle truck ratio and the % trucks (determined earlier by the location of the project) to find the appropriate load distribution to use.

•Growth Rate (From First Year) - CalME populates this field with a value based on the selected WIM group. You may change this value. This value represents the growth in traffic from the start date of the project onward. CalME applies a growth rate from the data of traffic observations to the start date of the project.

•First Year Axles / Design Lane - this is a readonly field that CalME populates with a value based on the selected WIM group.

•First Year Trucks / Design Lane - this is a readonly field that CalME populates with a value based on the selected WIM group.

•Design Life - CalME set a default value of 20 years. You may change this value. If you choose to design the pavement structure using either CalFP or CalAC, a Design Life of 20 years is required. You may specify any Design life for an ME design.

•Total ESALs - this is a readonly field that CalME populates with a value based on the selected WIM group.

•TI (Traffic Index) - CalME populates this field with a value based on the selected WIM group. You may change this value.

Making Changes to Growth Rate, Design Life and TI

Selecting a value for the WIM group sets the values for the other data items in the Design Lane Traffic Loads section. When you make a change to one of the editable fields, CalME will then recompute the other dependent values. For example, changing the TI will change: First Year Axles / Design Lane, First Year Trucks / Design Lane and Total ESALs; the WIM group and a Growth Rate are not modified. Also, changing the Growth Rate with change First Year Axles / Design Lane, First Year Trucks / Design Lane and TI.

The question mark in the blue circle in the upper-right of the control group allows you to get help on the controls (this topic).