Road Class Specifications dialog
This dialog is accessible as a tab on the Template Table dialog or from the Road Class Parameters button in either of the Curve Panels (Horizontal or Vertical). The parameters in this dialog define a type of road, they also help to define curves.
Road Class Specifications are stored with your Template Table, with the design, or externally. Each class of road will have a few typical cross section templates, a design speed and other parameters that are common from road to road. You should have a template table (TPL file) for each class of road you may design.
Simple Curves (check box)
If turned on, advanced curve editing functions are disabled. In Simple Mode, Design Speed, Reaction Time(s), Eye Height, Object Height, Deceleration and Acceleration cannot be edited and some functions in the Vertical and Horizontal Curves Panels are disabled.
If turned off, advanced curve editing functions are enabled. In Advanced Mode, the dialog box items can be edited and all functions in the Vertical and Horizontal Curves Panels are enabled.
For some RoadEng products, the Simple Curves check box is disabled and checked (Advanced Mode not allowed).
Road Classification
Description
Allows you to provide a description for the type of road.
Design Speed
Allows you to specify the maximum design speed for this road class. You will be warned in the Horizontal or Vertical Curve Panels- Advanced Mode if a design speed greater than this is entered.
Available in Advanced Mode only.
Driver Limitations (Advanced Mode only)
These items are used in the calculation of Sight Distance (Sight Stopping Distance) found in the Vertical Curve Panel. They are only used if Auto Sight Distance is turned on in the Vertical Curve Panel.
Reaction Time(s)
Allows you to specify the time it takes for the driver to react once he/she sees an obstacle.
Eye Height
Allows you to specify the height of the drivers viewpoint above the road.
Object Height
Allows you to specify the height of an obstacle in the road.
Vehicle Limitations
Minimum Radius
Allows you to specify a minimum radius for this road class. You will be warned in the Horizontal Curve Panel if a radius less than this value is entered.
Minimum Sag K
Allows you to specify a minimum Curvature (K) value for a Sag curve. You will be warned in the Vertical Curve Panel if the entered K is less than the minimum.
Minimum Crest K
Allows you to specify a minimum Curvature (K) value for a Crest curve. You will be warned in the Vertical Curve Panel if the entered Crest K is less than the minimum.
Deceleration ft/s/s or m/s/s
Advanced Mode only.
Allows you to specify a typical deceleration rate for this road class. Deceleration (stopping rate) depends on vehicle type and road surface type and conditions. This parameter gets used in the calculation of Sight Distance if Auto Sight Distance is turned on in the Vertical Curve Panel.
Acceleration ft/s/s or m/s/s
Advanced Mode only.
Allows you to specify a typical vehicle acceleration rate for this road class. This item is unused at this time but may be used in future for passing lane design.
Max Grade
Allows you to specify the maximum grade for this road class. Max and Min Grades are defined in the direction of increasing station value. A positive value is uphill in this direction while a negative value is downhill.
Min Grade
Allows you to specify the minimum grade for this road class. Max and Min Grades are defined in the direction of increasing station value. A positive value is uphill in this direction while a negative value is downhill.
Max Super Elevation
Allows you to specify the Maximum Super Elevation for this road class. A warning will appear if the maximum is exceeded in the Horizontal Curve Panel.
Tables
All the lookup tables below are saved with the template table (in the design and in an optional external *.tpl files). The tables can also be saved to, and read from, text files to allow you to edit the contents.
Super Elevation (button)
Advanced Mode only.
Used to look up super-elevation given radius and design speed. This table is used to calculate super-elevation automatically if it is set to be used in the Horizontal Curve Panel. The Auto Super Elevation Dialog allows you to define how the automatic super-elevation is calculated.
Max Side Friction (button)
Advanced Mode only.
Transition Length (button)
Advanced Mode only.
Used to look up transition length (super-elevation runoff) given radius and design speed. This is only applicable if transition length is set to automatic in the Horizontal Curve Panel.
Widening (button)
Used to look up curve lane widening given radius and delta (degrees). This is only applicable if widening is set to automatic in the Horizontal Curve Panel.
Degree of Curve
Stationing Distance
The stationing distance value is only used if you are reporting degree of curve values.
Degree of curve reporting is available in the Multi-plot horizontal curve table and in Plan window customizable labels; like radius, it is a way of measuring curvature in a horizontal curve. Degree of curve is defined as the angle subtended by a specific arc (or chord) length; we call this length the stationing distance.
Template Editor Options
These options are not available if you are accessing the Road Class Specifications dialog box from one of the Curve Panels.
Save Table (button)
Saves the templates, road class specifications, codes and materials for in a file (*.tpl) for future use. This step is strictly not required unless you want to make the template information available for other designs (template information is always stored with the current design).
Open Table (button)
Retrieves the templates, road class specifications, codes and materials from a template table file (*.tpl) or another Location design (*.dsn).
