faq 84705350

accessibility: some questions

by Rolando Armas on 2016-09-20 09:38:16

---

Hi Matsim Friends.

I have run my scenario using the accessibility extension.

I have some questions, could you help me, please?

1) For the accessibility computation, does it take into account the travel times which takes from the simulation (events file)?

If is that so,

2) Does it take from the last iteration? 

3) Is there a possibility to compute for each iteration?

4) I can not compute the accessibility for public transportation because I do not have the ptMatrix. How can I create the ptMatrix?

In the accessibility output we can find several files (for each facility type). 

5) I want to compute a unique value index which represents the scenario accessibility. Which one of those files, could you suggest me to use it for that? (I am thinking to use accessibility_indicators.csv but I am not sure).

Thanks again!

---

Comments: 2

---

Re: accessibility: some questions

by Dominik Ziemke on 2016-10-05 14:40:26

Hi Rolando,

sorry for my belated response because of vacation.

Concerning your questions:

1) Yes, the accessibility computation (for the mode "car") is dependent on simulation-observed travel times. (In cases where you run the accessibility computation without agents/plans, the results for the mode "car" mode will coincide with the results for "freespeed".)
2) Yes. (For the mode "car", the computation uses the class TravelTimeCalculator, which provides travel times (by default in 15min bins) from the latest previous information. Since the accessibility computation is called via a shutdown listener at the very end of a MATSim run, the computation is based on the last iteration of the run.
3) Theoretically possible, but not implemented. You would have to change the way the accessibility computation is started. It might work by starting the accessibility computation by an iteration ends listener instead of by a shutdown listener, but it is probably not that straightforward to change.
4) There is no standard way. I have an example to create a pt matrix based on a matsim transit schedule in playground.dziemke.accessibility.ptmatrix.CreateMatrixBasedPtInputs, which might help as a starting point.
5) Accessibilities that I compute are typically specified as follows: They are calculated FROM given measure points (usually lying on a regular grid) TO specific opportunities/facilities/activity types, based on a specific mode of transport, potentially for a given time of day. You could now neglect time of day and choose facilities that you base your computation on to whatever you see as representative. Along the other dimensions (mode, measure points) you could take averages. That would bring your computation down to one single value.

Cheers,

Dominik

---

Re: accessibility: some questions

by cui yi on 2018-06-25 12:57:45

Thank you for your reply!

In recently,I have try to use the ACCESSIBILITY. In the calculation result, the data always have only "freespeed" in defferent projecct. I think the reason is "accessibility computation without agents/plans".How should I to change these situation? I want the sccessibility computation to include the agents/plans.

Cheers,

Cui yi