Creating a Network / Accessability

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10-14-2012 10:36 PM
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New Contributor III
Hello everybody,

i must say that i'm a network analyst beginner. I need to model accessability for Tram-Stations (Only Pedestrian!). So my base-data (data based on OSM) is

the street-network (without motor- and highways)
the rail network
the footways
and the Tram-Stations as points


I tried to create a mulitnodal network, but like in the network analyst tutorial (Exercise 2: http://help.arcgis.com/en/arcgisdesktop/10.0/pdf/network-analyst-tutorial.pdf), there are no attributes created automatically. I think this is because of the missing information in the attribute table of the base-data. i read through the arcgis help, but i found nothing about the requirements of creating a multimodal network.

With which attributes i have to start with, before i can create a multimodal network (like in Excerise 2)??
i hope someone understands my problem and can help me a little bit (sorry for my english)

Best wishes,
Chris

PS: i tried to find (and get) the tutorial data to train a litte bit with it, but the customer care of arcgis is not very helpful (resp. i'm not able to get data from there).
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Occasional Contributor II
Hi,

Some basic info you need

1. travel time on each link (this can be same for both directions, or you could create different travel times for each direction with two attributes)
2. one-way restrictions

regards,
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New Contributor III
Hey,

is it necessary (before creating a network) to create a topology for the above mentioned feature classes? Or is it enough do define the relationships between the features classes by defining the connectivity?

My first step (before all others) is to check and repair the geometry.

best regards
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Occasional Contributor II
Hi,

Topology is important to make sure that your lines are connected properly. If you are sure of the connections of lines or if you are sure of the quality of the source from where you have the shapefiles or feature class, then you can skip topology. You can proceed to defining connectivity 🙂

If you do not have any attributes, just start with shape_length so that your solution is based on shortest distance. You can easily convert the distance to speed by diving it by average speed of the mode. For example, if it is a walking network, just use the speed between 3 to 4 km/hr, if bicycle take 10-15km/hr. So time taken = (distance/ speed). Then you can use the same procedures for shortest time.

regards,
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New Contributor III
Hi bsriramak,

thanks for your help and your explanations - i got the shapefiles from the internet, which are based on Open Street Map - so i think i should create a topology to be sure that that the quality is ok.

my seminarpaper deals with the fastest way to an touristic attraction so i need a starting point (1 - its open, but maybe the central station or something else) a network (2) and an endpoint (3 - touristic attraction) - by using network analyst for the servic area of tram stations. that means i need a multimodal network for pedestrian and for tram traffic (logically the pedestrian time is slower than the drive-time of the tram) [effectivly a integrated network (e.g. 3 min walk - 2 min waiting time - 5 min drive time - 4 min walk to attraction]

it is important to involve the average waiting time on the tram station - is there a way to model this issue within the network analyst?

best regards
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Occasional Contributor II
Hi,

yes you can give a average waiting time 1) same at each stop for whole network 2) same for each tram route 3) unique for each stop, as you may require.

All the options work in the same way. You have to have an attribute in your tram stop point layer, and later when building the network you can include these times in evaluators.

See here, this has exactly what you need, pedestrians and trams
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00470000005v000000

regards,
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Esri Regular Contributor
Hi Chris.  This might be too late to be helpful to you, but I think this tool might be helpful for your analysis: http://www.arcgis.com/home/item.html?id=42e57c5ff9a0497f831f4fced087b9b0.  It allows you to calculate buffers around your transit stops and weight them by the frequency of transit trips available or by the maximum wait time between any two trips.

Also, if you are considering making a multimodal network, there is a new prototype tool from Esri's Network Analyst team which allows you to add GTFS public transit data directly to a network dataset.  You can use this network dataset with the Network Analyst tools to run time-aware analyses that incorporate the transit schedules.
You can download the toolset and instructions here:
http://www.arcgis.com/home/item.html?id=0fa52a75d9ba4abcad6b88bb6285fae1
Please do not hesitate to contact me at mmorang@esri.com with questions or comments about this toolset.
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