About Head Up Display

The head up displays (HUD’s) show critical design values related to each arm.

By default they appear adjacent to each arm but they can also be displayed in a single table if required.

Each HUD has two grips, the one at the bottom left allows you to move it and the one at the top right lets you resize it (up to 5 times normal size). If the HUD is close to the roundabout leader lines will not be shown, even if specified, in the interests of clarity.

The color of the frame, line style and thickness may be changed using the HUD style.

Design radii & speeds

The displayed data is color coded to allow quick interpretation. The critical design radii and speeds calculated by Autodesk Civil 3D 2022 are shown green if they are within the limits specified in the standard and red if outside them. These values may also appear in amber when they get close to a limiting value if the user has defined a proximity warning percentage.

R1 to R3 and the corresponding V1 to V3 relate to the ‘through’ path, i.e. the nominally straight path through the roundabout. If there is no such path, these values display as N/A. Likewise, R4 and R5 (V4 and V5) relate to the 90 degree and 270 degree turns respectively and if either of these is not present this value is also displayed as N/A.

R1 to R5 are based upon the smoothed fastest path line. However, it is difficult to create the fastest path alignment consistently so a common alternative is to calculate the path using construction that is more easily repeatable. Therefore R1 Max, and the corresponding V1 Max, are therefore based upon the largest radius arc that will fit tangentially to the offset alignment at the start point on the approach road and tangential to the offset circle in the circulatory space. As such it is a more conservative radius that leads to higher estimates of entry speed.

Note: It is possible that, under certain circumstances, R1 may exceed R1 Max. This is because the two values are measured quite differently, and even though the entry path may have a significant radius overall, the radius in the vicinity of the yield line may be far less.

ARCADY values

The data passed back from ARCADY is displayed in the colors and units specified in the corresponding ARCADY data file.

Other values

You can also display the analysis input values in the HUD as well as some other geometric data such as the ICD. These values are displayed numerically with no color coding.