Content Comparison

Properties

Lane Width: The combined width of the vehicle (usually 6 ft) and its margin (1 or 2 feet) should not exceed the Lane Width, which is typically 12 ft.

Margin btw. Vehicle & Lane Edge : This is referring to the lateral distance from both sides of the lane where vehicles cannot be placed. The wheel load of any vehicle cannot be positioned in this specific location.

Vehicles

It is utilized to define a vehicle, vehicle's impact factor and direction within a single Design Lane in the longitudinal direction. Typically, AASHTO recommends placing one or two vehicles in the longitudinal direction within a single lane. Using the vehicle 1, vehicle 2, vehicle 3, and vehicle 4 parameters, OpenBrIM allows users to position up to four vehicles in the Design Lane's longitudinal direction. It should be noted that this does not apply to the placement of the Design Lane in the transverse direction, which is determined by the roadway width and design lane width.

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Vehicle 4 Impact Factor:

Vehicle 4 Direction:

Lane Load

Lane Load Magnitude: The design lane load, as defined in AASHTO LRFD, is typically 0.64 klf and expressed as force per unit length. It is used in conjunction with the design truck or tandem. OpenBrIM applies the lane load in both transverse and longitudinal directions on a design lane only if it increases the critical force effect. As indicated in the screenshot below, the red and yellow regions show the areas that can be loaded with the lane load for negative force effects, whereas the green and blue regions show the areas that can be loaded with the lane load for positive force effects.

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Afterwards, this value is multiplied by the areas (i.e., red and yellow regions, as shown in the screenshot below) that contribute to maximizing the lane load force for negative force effect.

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Vehicle Placement Settings

Min. Vehicle Spacing [Back to Front]: If there are multiple vehicles defined for the design lane, the spacing between them in the longitudinal direction cannot be less than the entered value. For example, in the case of two trucks for HL93, the typical value for this spacing is 50 ft per AASHTO.

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Adjacent Span Placement[Yes/No]: The placement of the two-truck vehicle shown below is not compliant with AASHTO standards because both trucks are located on the same span. To prevent this type of placement, the user should select adjacent span placement as “Yes”.

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Lane Placement Settings

Apply Lane Constraint[Yes/No]: Lane placement constraints are implemented to prevent the placement of lanes in a specific section of the roadway perpendicular to the direction of travel. If "yes" is selected, and the start and end parameters for the constraint are entered, the placement of lanes will only be in that region.

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