Trimble Business Center

Over the past week or so I have had a couple of Road Alignment Questions that I thought worth capturing here for all you Roadies out there

1) I have a HAL and I have been given a bunch of elevation values at Stations along the HAL - how can I create a VAL from these Station / Elevation values?

2) I am building alignments for Curb and Gutter Machines that utilize provided Curb Lines as alignments - however I have to add a straight tangential section at the start of the alignments for e.g. 100' before the start of the line / curb so that the machine has a run in length to get it on line and oriented before it starts paving. If I create a HAL / VAL from a Linestring, how can I add the 100' of additional line to the start of an alignment?

I have provided answers below as well as a short video on how to do these two things

Alan

The answers to these questions are as follows

To create a "VAL" from Station and Elevation pairs that match up with a HAL you can do the following

1. Create the HAL
2. Create the Corridor using the HAL as the Horizontal Alignment. Do not select a VAL
3. Create a Template starting at the start station of the alignment
4. The first instruction in the Template will be your "VAL" - use an Offset Elevation instruction. For the Offset use 0 from the HAL and for the Elevation use a Table and either enter your Station / Elevation pairs manually or Right click the Header Line and select Paste (from eg Excel spreadsheet).Do not add the Node that you just created to 
5. This has now created your first Node which is the VAL effectively. You can now hang all your surface instructions off it

The second question on how to edit a HAL and VAL to insert a line extension of 100' at the start of the alignment so that a Curb and gutter machine has 100' of run in to get itself on line, in orientation and at grade so that when it hits the ) station point of the Curb it can start Paving. There are two potential solutions to this using the Alignment tools in Business Center - HCE - I have captured both on Video here and that is likely to be easier to understand than a text description

Hope this helps

Happy Modeling

Alan

Alan

I had a customer call about this tonight.  On your simple HAL, VAL for the curb example.  If I change the stationing to 100+00 and then create the VAL in the editor, and append the same linesting to get the vertical data, the VAL editor changes the 100+00 to 0+00; meaning the HAL and VAL don't lineup.  In a simple example that can be edited.  With a complex linesting it's a mess.  Is there a way to get the VAL Append Line to match your HAL stationing?  Worse case (picture below) my VAL is offset 1015' left (east) and I get incorrect information.  Honestly I've never noticed than before (VAL Stationing difference).  Same thing if you select Use Existing Line before you go into the editor as it pulls both HAL and VAL data simultaneously.

Tim

A few comments here

1) When you enter the Alignment Editor you have two options if you want to use a Linestring to form the alignment elements

   a) you can select a Linestring as you start to Create the Alignment before you get into the editor. If that Linestring is a 3D line then this process will create both a HAL and a VAL.

   b) If you however do not pick it here and get into the Alignment Editor then from the HAL tab  you can pick any linestring as the HAL only and again from the VAL tab you can create a VAL and then select any linestring as the VAL only. (They don't even have to be the same line (see next post on this subject).

2) If you use option 1a, then I can change the Station for the start of the HAL to say 100, and that has no effect on the VAL (it still starts at 0) based on my quick test here. In the HAL if I change the Start Station of the alignment, all subsequent stations are updated automatically because we have the geometry to compute that. However if I change the start station of the VAL it doesnt update all of the subsequent stations (because we dont have the geometry to do that. If you want to shift the Profile to match the new HAL stationing then create a New Profile view of the HAL and then you can use the Move command to move the profile from 0,0 to e.g. 100,0 if that is the new start station - now the HAL and VAL will match stations again.

3) If I use option 1b then I change my HAL start station to eg 100 then I see the same behavior in the editor again - the VAL stays at station 0. It is not trying to change anything - it just doesnt know the stationing from the linestring.

So

If you do the following

1) Create an alignment, do not select the Linestring as you start to create the alignment - wait till you get to the editor

2) In the HAL Editor, use the Create from Linestring and select the line you want as your HAL - it will create the HAL with start station 0. You can change the Start Station e.g. to 1015 and then Tab Tab over the coordinates and it will update all of your stations for the HAL by 1015

3) Open the Vertical Alignment Tab

4) Select Create Vertical Alignment to create the holder for the VAL

5) You should see that the start station picks up the start station from the HAL e.g. 1015 - if the VAL starts at the same location as the HAL then you can simply use the create from Linestring command and it should append the linestring but starting at station 1015 so no need to move it afterwards.

if however your VAL linestring is for some reason 100' longer than the HAL linestring then you could enter 915 where it says 1015 and then without entering a Z value you can append the linestring and it's stationing will now start at 915 for the vertical and 1015 for the Horizontal.

Last Point here - going back to the Initial Question at the start of this thread

If you were given a bunch of Station and Elevation points for a VAL and your HAL is Curvilinear, while you can import the points as Station Offset = 0 Elevation to create the points at the correct stations, you could then join them togetjer with a linestring (especially if you gave each line an ID like AS1, AS2 .... etc. ) however the problem now is that the Linestring is chorded wheras the alignment is curvilinear so the chorded line stations wont match up correctly - the method I gave in the video above is one way to resolve this, however if for some reason you really want a VAL on the HAL with the correct stations - how do you solve that

What I would do is treat the Station values like an Easting, create a Column for Northing and set those to 0, and keep the ELevation Field as Elevation. I would add an ID column in front of the Easting. I would create a Description Field after the Elevation. I would save as a CSV file in the format of P,E,N,Z,D. 

Now Import the Points into your project - they will form a line gong from West to East starting at the West end at 0 Northing.

Create a Linestring between the points using the Linestring From Points command - enter AS1 - AS54 (or whatever your Point ID range was) to connect the dots. You now have a 3D linestring where the Stationing is correct and matches your HAL

Now edit your Alignment and open the VAL editor. Create a VAL. Enter the start station you want in the first field if other than 0 or different to the one shown which should match the HAL. Now append the Linestring you just created - Note it is a completely different line to the HAL linestring and its sole purpose here is to provide the Station Elevation Grade Beak locations to your HAL - this is an alternative way to solve this problem.

You can now delete the Points and Line because you have married them correctly together on the HAL

Be aware that this is all great on HALs / VALs where there are no Station Equations. Be very careful trying to manipulate alignments where they contain Station Equations.

Hope that this all helps

Alan

Here is a video of that workflow described in the previous post

Alan

Mine keeps resetting to 0+00.

I get the same reset to zero station....

How do you get the "Crosshairs" and Station/Offset to display in the plan view?

Explore Object : Horizontal Alignment

I use explore object on the corridor ribbon 

make sure you alignment selected

Tim,

The same thing happened to me when I tried. This is something a colleague and myself have struggled with for a while now. 

Bravo!!!!