Carslon RoadNET: Adding and Editing Cul de Sacs

Carslon RoadNET: Adding and Editing Cul de Sacs

Cul-de-Sacs may be added to any Road in the Network and are managed in the Cul-de-Sac area of the Road Network: Task Pane.

Add: Pick the Add button or right-click on Cul-de-sacs in the project tree and choose Add to display a list of Roads in the Network and prompt the user to“Select Road for Cul-de-Sac”…. After selecting the Road, the Edit Cul-de-Sac dialog box is displayed allowing the user to specify the Input Data and Output Files for the Cul-de-Sac.
Edit: Use this button to display the Edit Cul-de-Sac dialog box and make changes to the Input Data and Output Files for the selected Cul-de-Sac.
Remove: Use this button to Remove the selected Cul-de-Sac from the Road.

Add Cul-de-Sac

Add: Picking this button displays a dialog box listing the Roads in the Network and prompting the user to Select Road for Cul-de-Sac.

CS 1

Select Road for Cul-de-Sac

After choosing the Road and picking the OK button, the Edit Cul-de-Sac dialog box is displayed.

Edit Cul-de-Sac

CS 2
Cul de Sac Input Data

Cul-de-Sac Centerline Position: Use this radio button to specify whether the Cul-de-Sac is drawn at the starting or the ending station of the Centerline.
Centerline Direction: This setting applies only if the horizontal alignment of the Cul-de-Sac is to be saved externally as an Output Centerline (.CL) file. If so, this setting determines which end of the Cul-de-Sac is the starting and which is the ending station of the new Centerline (.CL) file.
Center Station: Use this setting to precisely locate the center of the Cul-de-Sac along the Road Centerline. By default, the Center Station is the starting or ending station of the Centerline depending on whether the user has chosen Start or End as the desired Cul-de-Sac Centerline Position. The station for the center of the Cul-de-Sac may also be entered in the text box or may be specified using a Delta value. When using the Delta option, the Cul-de-Sac will be shifted the specified distance along the Centerline.
Cul-de-Sac Radius: Use this value to specify the radius of the Cul-de-Sac bulb. The Cul-de-Sac Template ID determines the point on the cross-section being affected by this setting.
Fillet Radius: Use this value to specify the radius of the curve that transitions between the Road and the Cul-de-Sac. The Cul-de-Sac Template ID determines the point on the cross-section being affected by this setting.
Offset: When set to “0”, this setting places the center of the Cul-de-Sac on the Centerline of the Road. Setting this value to a negative(-), greater than “0” value will shift the center of the Cul-de-Sac left of the Centerline by that distance. A positive, greater than “0” value will shift it to the right by that distance.
Tear Drop Mode: Enabling this option creates a longer transition between the Road and the Cul-de-Sac. When enabled, a value larger than the Cul-de-Sac Radius must be entered as the Setback. An example of a “Tear Drop” Cul-de-Sac having a 45′ radius and 75′ setback is shown below.

CS 3

Example of Tear Drop Cul-de-Sac

Template ID: This is the point on the cross-section used to define the horizontal (Centerline) and vertical (Profile) alignments around the bulb of the Cul-de-Sac. The Template ID may be specified as any point on the cross-section – such as edge of pavement (EP) or the back of curb (BC) – as long as it has been defined as a Template ID in the Template (.TPL) file used for the Road. Type the Template ID in the text box or use the Select button to choose from a list.
Profile Transition VC: When adding a Cul-de-Sac to the Road Network, the Profile around the Cul-de-Sac is automatically generated having 3 PVIs – one on each end connecting to the Road and one at the mid-point of the alignment. The Profile Transition VC setting is the default length of vertical curve inserted at the middle PVI of the Profile. As shown below, adding a vertical curve at this PVI can have a significant, positive impact on the resulting surface model and contours of the Road Network.

CS 4

Effect of Adding a Vertical Curve to Cul-de-Sac Profile

Edit Profile: Pick this button to open the Input-Edit Road Profile Editor and make changes to the Profile of the Cul-de-Sac. The Cul-de-Sac Template ID determines the point on the cross-section being represented in the Profile Editor. See Road Network: Road Profile Editor for more Help with this feature.

CS 5

Edit Profile for a Cul-de-Sac

Reset: Use this button to overwrite all edits to the Profile of the Cul-de-Sac and reset to the original Profile.
Template: Use this button to browse to and select an existing Cul-de-Sac Template (.TPL or .TSF) file. Specifying a different Template than the main Road allows the user to define different features for the Cul-de-Sac area such as sidewalk and curb.

Cul de Sac Output Files

Centerline: Pick this button to output a Centerline (.CL) file representing the horizontal alignment around the Cul-de-Sac. The Cul-de-Sac Template ID determines the point on the cross-section exported to the Centerline (.CL) file.
Profile: Pick this button to output a Profile (.PRO) file representing the vertical alignment around the Cul-de-Sac. The Cul-de-Sac Template IDdetermines the point on the cross-section exported to the Profile (.PRO) file.
Existing Section File: : Pick this button to output an Existing Section (.SCT) file for the Cul-de-Sac.
Final Section File: Pick this button to output a Final Section (.SCT) file for the Cul-de-Sac.

Note: Driveways around a cul-de-sac can be easily added simply by drawing polylines for their centerlines and snapping them to the EOP of the cul-de-sac.

Click here to start the Practical Lesson

Recent Posts

Jam proofing drones

“Collect 1 million data points from a 15-minute flight compared to 300 points in a day from a traditional ground survey. It’s no wonder that drones equipped with GPS technology and remote sensors are revolutionising data collection. But will jamming spoil all the fun?”

Who let the drones out?

Recent years have seen the appearance of affordable, high-end drones which, coupled with easy-to-use mission-planning tools, has created the perfect environment in which drones can flourish. No longer the preserve of specialist drone users, applications using drones have been venturing into areas such as survey, inspection and volume analysis with an impact that is little short of revolutionary.

Interference can spoil it all

In the air, the stakes are higher. When things go wrong, the consequences are invariably much more serious than they would have been on the ground. One of the biggest threats to drone safety is GNSS interference. At the very least, disruptions to satellite signals can degrade position quality causing fall-backs from high-precision RTK and PPP modes to less-precise modes. In the most extreme cases, interference can result in complete loss of signal tracking and positioning.

Self interference

A significant source of interference on UAVs is often the other components installed on the UAV. The restricted space means that the GNSS antenna is often in close proximity to other electrical and electronic systems.

gopro_interference (1)

Figure 1: GoPro Hero 2 camera pick-up monitored by an AsteRx4 receiver

Figure 1 shows what happened to the GPS L1-band spectrum when a GoPro camera was installed on a quadcopter close to the GNSS antenna without sufficient shielding. The three peaks are exactly 24 MHz apart pointing to their being harmonics of a 24 MHz signal: the typical frequency for a MMC/SD logging interface.

An AsteRx4 receiver was used in this setup which includes the AIM+ system. As well as mitigating the effects of interference, AIM+ includes a spectrum plot to view the RF input from the antenna in both time and frequency domains. At the installation stage, being able to view the RF spectrum is an invaluable tool for both identifying the source of interference and determining the effectiveness of measures such as modifying the setup or adding shielding. For the quadcopter installation in this example, the loss of RTK was readily diagnosed and solved by placing the camera in a shielded case while the quadcopter was still in the workshop.

External sources of interference

GNSS receivers on-board UAVs can be particularly vulnerable to external sources of interference, be they intentional or not. In the sky, the signals from jammers can propagate over far longer distances than they would be able to on land.

In the case of UAV inspections of wind turbines for example, many countries encourage windmills to be built next to roads, a situation that increases the chance of interference from in-car chirp jammers. These devices though illegal are cheap and can be readily acquired on the internet. Using a chirp jammer, a truck driver can, for example, drive around undetected by the GPS trackers on the truck and car thieves can disable GPS anti-theft devices on stolen vehicles.

External interference: the effect of a chirp jammer on a UAV flight

Although transmitting with a power of around only 10 mW, chirp jammers are powerful enough to knock out GNSS signals in a radius of several hundred metres on land. In the air, the UAV is much more vulnerable as the jamming signals have a far greater reach, unhindered as they are by trees, buildings or other obstacles.

Figure 2 shows how a 10mW chirp jammer can knock out RTK positioning over more than 1 km in a high-end receiver. Even a low-end consumer-grade L1 receiver, being less accurate and thus less sensitive, loses standalone positioning over several hundred metres.

 With AIM+ activated, the AsteRx4 is able to maintain an RTK fix throughout the simulated flight as well as showing no degradation to its position variance. The full details on these simulations can be found in a recent white paper.

Solving interference on UAV systems

A comprehensive approach puts interference considerations at the forefront of receiver design and incorporates it into every stage of signal processing. In the case of the AsteRx4 and AsteRx-m2, the antenna signal is immediately digitised after analogue filtering and automatically cleansed of interference using multiple adaptive filtering stages.

As each interfering signal has its own individual footprint, being able to visualise the RF signal in both time and frequency domains allows drone users to identify sources of self-jamming and adapt their designs accordingly before the drone gets in the air.

When it is in the air, AIM+ is able to mitigate jamming from external sources: a set of configurable notch filters are complemented by an adaptive wideband filter capable of rejecting more complex types of interference such as that from chirp jammers, frequency-hopping signals from DME/TACAN devices as well as high-powered Inmarsat transmitters.


Figure 2: RTK position availability for the AsteRx4 with AIM+ activated and a comparable high-end receiver. The low-end receiver tracks L1 only and outputs less-precise standalone positions. A 10mW chirp jammer is located on the ground at position (0,0) as shown.

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