topic Re: Want to build a new Network in ArcGIS Network Analyst Questions

Want to build a new Network

JeffreyTippen — Wed, 16 May 2012 13:31:00 GMT

Hello everyone,

I work for a organization who uses a very labor intensive routing program for school district transprotation routing. I would like to switch over to ESRI solution using Network Analsyt. Our district services approx 65,000 students of which about half require transportation to 67 schools. We have a fleet of about 400+ buses. We keep growing and have out grown our current process.

I do have many off and on years of ArcGIS expeirience but mostly on single workstation.

I guess my beginning questions would be on reccomended reference materials so I can approach this the right way. I will have to create a test network to demonstrate the capability and advantages of a geodatabase to support not only the Transportation group but other divisions within the district.

I would appreciate any advice from current users of the best approach I should take. Since I'm starting from scratch I would like to stay on tract.

Thanks in advance for your time

Jeff

Re: Want to build a new Network

JoeBorgione — Wed, 16 May 2012 13:40:18 GMT

Hello everyone,

I work for a organization who uses a very labor intensive routing program for school district transprotation routing. I would like to switch over to ESRI solution using Network Analsyt. Our district services approx 65,000 students of which about half require transportation to 67 schools. We have a fleet of about 400+ buses. We keep growing and have out grown our current process.

I do have many off and on years of ArcGIS expeirience but mostly on single workstation.

I guess my beginning questions would be on reccomended reference materials so I can approach this the right way. I will have to create a test network to demonstrate the capability and advantages of a geodatabase to support not only the Transportation group but other divisions within the district.

I would appreciate any advice from current users of the best approach I should take. Since I'm starting from scratch I would like to stay on tract.

Thanks in advance for your time

Jeff

Jeff- big task! Start here...

Good luck!

Re: Want to build a new Network

JaySandhu — Wed, 16 May 2012 16:53:49 GMT

The Network Analyst tool you need to ultimately use is the VRP solver. However I will suggest that you start with the free streetmap data that comes with with ArcGIS. It is a free nationwide street network. It is on the data and maps dvd and it is ready to use out of the box.
You can also find in online to download if you do not have the dvd.

Besides the tutorials, online resources on ArcGIS.com, etc., you can watch this VRP video to get a bit more familliar with it:
http://video.arcgis.com/watch/686/vehicle-routing-problem-example-appliance-delivery

Jay Sandhu

Re: Want to build a new Network

JeffreyTippen — Fri, 22 Jun 2012 12:50:26 GMT

Well I would like to give everyone an up date.

I working on finishing my street layer. I have been fortunate to receive about 85% of my districts streets. I'm currently attempting to digitize the rest.

I do have a question. My district partially contains 3 counties. I've received parcel data from 2. I coverted them to a point file which contains approx 86,000 residences. Would this data layer help better define locations for network analyst than just geocoded streets? It seems to me that by moving the point (calculated at center of parcel poly) to front of residence then assigning students to that point could better define their locations. Is this over kill or is this a logical assumption?

Again as I stated in my original post, I'm starting from scratch. My target date is June 1, 2013 to go online.

Also, would Red Light and Stop Sign locations provide better timing estimates?

jt

Re: Want to build a new Network

BradShore1 — Tue, 26 Jun 2012 20:48:21 GMT

Your project sounds very interesting.

I would try to get the parcel data from the 3rd county if possible. From the parcel data make a single house address locator. Then you can geocode the students that need transportation (I'm assuming you have a list of them) and use that feature as an input for you network analysis.

What attributes do your streets have? Do they have MPH? Without MPH, you won't be able to calculate time for you network. Do they have address ranges? If so, you can create a single-range or dual-range address locator depending on the data. Creating a composite address locator of the parcels and streets, you should be able to gecode a majority of the students accurately. I think this is the most important part. If you can't accurately locate the students, what good is it to make bus routes for them.

To determine bus routes, you might look into using the location-allocation analysis layer. I'm not too familiar with location-allocation, but it might help. Once you determine bus stops, as Jay said, use the VRP analysis layer.

I hope this helps give you some ideas on how to proceed. Good luck!

Re: Want to build a new Network

JeffreyTippen — Thu, 28 Jun 2012 10:29:33 GMT

Thanks for the reponse Brian,

Hopefully I can get the missing parcel file though it doesn't cover much of our district.

With the streets I do have addresses and speeds. I used the street file from ESRI for half of the streets and merged the other half from a county supplied file. I assume I need to create a turn file, stop sign file and red light file as separate layers. Our district has grown so quickly in the last 5 years that I need to create some kind of traffic layer. I do need to read about what that file would contain.

I was thinking of trying a proximity (sp?) analysis based on eligible kids maximum walking distance to predict where optimum stop locations should be placed. I'm still green around the gills on the network analys tool kit but it doesn't appear to be very difficult to use. I assume that once i have all my stop locations set then I start applying VRP's for each attendance boundary for run locations.

Not sure which tool to use for building routes of my runs. We use a two bell system so I will need to pair up morning and afternoon runs. Also since we have three depots I'll need to optimize my fleet distribution. I do have a few country runs so I'll need to make sure my most efficent buses are being allocated for those long distance runs.

Of course I haven't even began to incorporate special needs run. I thought I would first tackle normal runs first then address special need's buses.

Jeff T

Re: Want to build a new Network

JeffreyTippen — Thu, 26 Jul 2012 12:42:11 GMT

OK I need some advice on incorporating stop signs and Red light intersections. I've identified all my red light intersections and working on the stop sign locations. Are these created as point features and then loaded into a VRP analysis?

Jt

Re: Want to build a new Network

JoeBorgione — Thu, 26 Jul 2012 14:57:27 GMT

OK I need some advice on incorporating stop signs and Red light intersections. I've identified all my red light intersections and working on the stop sign locations. Are these created as point features and then loaded into a VRP analysis?

Jt

You should be able to use them as barriers with some sort of impedance value. An alternative is creating turns, and they can get ugly...

Re: Want to build a new Network

JeffreyTippen — Fri, 27 Jul 2012 13:54:26 GMT

Thanks Joe for the reply.

I looked at the barrier part in the resource guide and then I was reading about turn tables. I guess I need to build a table for all my intersections and put a time cost if there is a stop sign or red light for each of the turns. I've expierimented with the network builder on my test file. Is there a turn table aready created at each intersection? I need to dig into what all was created when I built the network.

Again thanks for the help. I'm such a noob at this but I think I'm finally beginning to break the egg shell.

Jeff T

Re: Want to build a new Network

JeffreyTippen — Fri, 27 Jul 2012 14:48:26 GMT

OK I read more on turn and see that I have to create them. I see that I create the turn file in Arc Catalog and then create them one at a time (ugh). Oh well onward we go.

Jeff T

Re: Want to build a new Network

PatrickStevens — Fri, 27 Jul 2012 15:42:28 GMT

You should be able to use them as barriers with some sort of impedance value. An alternative is creating turns, and they can get ugly...

Barriers can be a viable solution, but I would recommend using your stop light points as a junction source in the network. Be sure that your stop light junctions are coincident with the source junctions for the affected intersections.

Once the new junction source is built into your network, there are a couple of options on how to set the delays. If you have one generic value for the delay at every light (say 5 seconds), then use a constant evaulator on that junction source with a value of 5. If you have different delays for each light, then set up a field on your new junction source (say "Delay"), then use a field evaluator that reads the Delay value in.

Constant evaluators are the fastest of the evaluators, as the value is set. Field evaluators are next fastest, as the values are processed when the network is built, not dynamically as the solve occurs.

The caveat with this implementation is that your stop light delay will be incurred no matter what the maneuver at the intersection is. A left turn, a right turn, a U-turn, and driving straight through the intersection will incure the same delay coming from every direction that passes over the new junction.

That same caveat would apply for the point barrier implementation as well, though. Turns are the most accurate solution, as they give you more refined control, but as you know, there can be A LOT of turns to digitize.

Another potential solution is the Global Turn Delay Evaluator (GTDE). If, as dicussed previously, you have a generic set of delays depending on the type of maneuver, you can use this evaluator to specify them. The GTDE works based on type of turn (straight, left, right, u), as well as road designations (local, secondary, major). Your level of control can be as fine as a specific, generic delay for every left turn from a local road onto a major road, for example.

Re: Want to build a new Network

JeffreyTippen — Mon, 06 Aug 2012 15:52:08 GMT

OK,

I'm working on the best way to handle stop signs.

I have another question that I have been putting off. In addition to our normal bus fleet we have about 100+ special needs buses. I was planning the network to prevent the regular buses from turning onto cul-de-sac streets or others that would be difficult to turn around on. Since our special needs buses are shorter they can enter and turn around in cul-de-sac streets.

My question is: Do I need a separate network for special needs over the district?

Or is there a way to code the bus to allow it to enter cul-de-sac or dead end streets using the normal street network?

I hope I'm clear on this. I know I will be asked alot of questions regarding special needs routing.

Thanks in advance,

Jeff

Re: Want to build a new Network

PatrickStevens — Tue, 07 Aug 2012 14:55:17 GMT

In addition to our normal bus fleet we have about 100+ special needs buses. I was planning the network to prevent the regular buses from turning onto cul-de-sac streets or others that would be difficult to turn around on. Since our special needs buses are shorter they can enter and turn around in cul-de-sac streets.

My question is: Do I need a separate network for special needs over the district?

Or is there a way to code the bus to allow it to enter cul-de-sac or dead end streets using the normal street network?

You are working with what we call the "U-Turn Policy". There are 2 places where you can adjust u-turns. Here's a link to the help topic about it. You do not have to make changes to your network to use either of the properties.

The first concept is called "Curb Approach". This will set how the vehicle approaches its stops. Should the vehicle arrive on the same side as the stop? And can the vehicle make a u-turn when it leaves the stops?

The second concept is called "U-Turns at Junctions". This option governs how the vehicle behaves when traveling between stops. When the shortest path includes making a u-turn at an intersection or at a dead-end, can my vehicle handle this type of maneuver?

Curb Approach is set in the properties of the stop itself. U-Turns at Junctions is in the analysis settings for any of the solvers you might use.