Download current version of the CAP VISTA software - CETE

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Transcript
1
draft paper for ITS Geneva

November 2007
Draft paper title :
CAP VISTA, a database for calculating, analysing and mapping travel times
based on GPS tracklogs

authors :
Patrick GENDRE, Didier GOUDERGUES, CETE Méditerranée, Alexis BACELAR, CERTU,
Fouad KHODJA, ICIA Technologies ; Philippe MARCHAL, INRETS


Topic: Traffic and transport management, focus: reliability and keywords : GPS, travel
time, road information, multimodal information, GIS, database
Paper abstract (200 words maximum)
CETE Méditerranée, a technical centre of the French ministry of transport, supported by
national centres CERTU and INRETS, developed a prototype version of a GPS Travel Time
Database, enabling the reconstitution of travel times on road segments from GPS tracklogs
and a digital road database in a GIS software.
The prototype was evaluated in early 2007: the first tests showed the feasibility of deriving
useful information from GPSs and digital maps at a modest price, and expressions of interest
from local urban and inter-urban traffic managers, and led to the development of a second
version in Fall 2007.
The software, called CAP VISTA (which stands for Travel Times Computation, VISualisation
and STAtistics), has been developped by ICIA Technologies, based on their GrfMap GIS
software. The licence costs around 1500 Euros, a GPS terminal costing around 100 Euros.
This article presents the software application, the first usage made with it, and perspectives
for the year to come, including application for other modes than car.

Author’s full contact details
Patrick GENDRE
CETE Mediterranee (DCEDI/DERIS/TIER)
Pole d'activite CS 70499
13593 Aix-en-Provence cedex 3 - FRANCE
+33 (0)4 4224 7687
[email protected]
www.cete-mediterranee.fr/tt13/www/
2
draft paper for ITS Geneva

November 2007
Draft paper (3 pages)
context
Why work on differed time travel time database ?
Travel time (TT) is being recognised as a key indicator for the quality of service on road
networks, and for user information. Real time travel time display systems are being deployed
worldwide. Constituting historical travel time database and showing recurring congestion
information to the users is a less common practice of traffic managers, although a large part of
congestion is recurrent, and can be measured in terms of travel time and travel time
variability. GPS terminals lowers considerably the cost of travel time measurement and offers
an opportunity to improve our knowledge of the true door-to-door times and reliability.
In France, archived congestion information is used by traffic info web site such as DIRIF for
the Paris freeways, and ASF for Southern France tollways.
In the US, a digital map editors such as Tele Atlas now sells historical mean speed by time of
the day over more than 500, 000 miles of US highways.
Goals of the project
CETE Méditerranée, a technical centre of the French ministry of transport, developed a
prototype version of a GPS Travel Time Database, inspired by the GETT software (GPSBased Evaluation of Travel Time). The GETT software, developed in 2002 by the University
of Texas, enables the reconstitution of travel times on road segments from GPS tracklogs and
digital road database in a GIS software.
Our prototype was evaluated in early 2007: the first tests showed the feasibility of deriving
useful information from GPSs and digital maps at a modest price, and expressions of interest
from local urban and inter-urban traffic managers, and led to the development of a second
version in Fall 2007.
The software, called CAP VISTA, has been developped by ICIA Technologies, based on their
GrfMap GIS software. The licence costs around 1500 Euros, a GPS terminal costing around
100 Euros.
This article presents the software application, the first usage made with it, and perspectives
for the year to come.
current version of the CAP VISTA software
CAP VISTA stands for “CAlcul de (temps de) Parcours, VIsualisation et STAtistiques”
(Travel Times Computation, VISualisation and STAtistics).
The GPS terminals
Based on a cooperation with INRETS/DEST lab, who pioneered in France the use of GPS a
complementary tool for the 2007 National Travel Survey, we chose a tiny, easy to use, low
cost model from Royal Blue Tek. They have an autonomy of 8 to 16 hours depending on the
battery used, and can store up to 30,000 points. Data are uploaded to a PC via a BlueTooth
link.
However, the application can work with any tracklog file in the standard NMEA format.
3
draft paper for ITS Geneva
November 2007
Illustration 1: GPS Royal tek RBT1100
Data models
An important by-product of the project is the definition of some useful notions for GIS
transport software, and of the corresponding data model. The terms may need to be adapted or
better translated to English, but the definitions are quite stable :
- tracklog (trace in French) : a point measurement made by a GPS terminal
- trip (trajet) : a tracklog without stops of more than a few minutes (15 by default)
- run (parcours): the projection of on individual segments of the reference; it is the elementary
data for travel time
- segment (tronçon) : an object from the reference map
- route (itinéraire) : a sequence of runs
The software can take account of arbitrary time windows, e.g. compute mean or median speed
for the 08H00-08H30 and 8H30-09H00 intervals. Additional explanatory factors can be added
in the runs table, such as day type (weekday, week-end...) or weather (clear, rainy, fog...).
Functionalities
In order to obtain an operational travel time database, the user has to ask Cap Vista to:
- define the reference road network segments as a GIS data layer
- define the database where data will be stored (which can be MS Access or any other, such as
postgres/postgis)
- import GPS tracklogs and updates the database
- map match the tracklogs to the reference network and computes travel times on the reference
segments
- compute/update statistics on the road segments
- define routes and compute/update statistics on route
- visualise the results (as layers on the GrfMaps, and as diagrams)
- export the data to other software such as XL, matlab, R and analyse the results
The map matching algorithm is quite basic; however, it proved to yield satisfying results,
provided the user has defined a reasonable network of reference (not precise). Of course, the
measurements being more difficult in a dense urban environment, the data will be easier to
obtain in peri-urban and inter-urban settings.
The definition of travel times on routes is quite basic too, as it is calculated by summing
mean/median travel times on individual segments. It works well as long as enough data are
collected and when the time window for the statistics is larger then the typical travel times.
However, it would be possible to implement other travel time prediction algorithms.
Several visualisation are provided, thanks to the capabilities of the GrfMap GIS: maps of
average speed for each segment or travel time for each route, bargraphs of average travel time
or speeds on depending of time of the day, etc.
4
draft paper for ITS Geneva
November 2007
Use cases
Very often, travel times are not measured except on the major motorways and a few major
arterials, or are measured punctually for a specific study. The basic use case for CapVista is
that a traffic manager wants to build up a TT database so as to have a better knowledge of the
level of service (congestion, variability). Over time, its own vehicle fleet will pass over the
managed network and collect data. The goal is not to have real time, but to have
representative data over the network; eventually, when more data are collected, the database
can also provide good estimates of TT variability. The TT data can then feed other application
such as route planning, isochrone maps, traffic models, and so on.
proposed improvements
Although most users will study car travel times, the GPS tracklogs can work also for walking,
cycling or public transport segments. The current version of CapVista can be used for transit
schedule adherence / regularity studies : the reference network has to be defined so that the
segments correspond to the public transport routes studied. However it may be more practical
to use zones (e.g. around transit stops/stations) rather than a reference network for this kind of
studies. We envisage to add this functionality in a future version.
We plan to test this with local administrations, transport authorities or network operators.
Other envisaged use cases included :
- accessibility studies to a business area, in the realm of entreprise mobility programmes ;
- urban : time to find a parking place, green waves optimisation...
Also, there has been several R&D work on automatic mode identification from GPS
tracklogs. This cannot be set as a short term goal, however, as the problem is very difficult.
CETE Meditérrannée has been in contact with the CNRS/LET lab in Lyon, who work on
software tools for feeding their traffic models with GPS travel times.
conclusion
Developed with a modest budget, the Cap Vista software is an interesting and affordable tool.
Several use cases are possible but still needs to be tested, and may imply to add new transport
GIS functions to the software. CETE Mediterranée is looking for operational services willing
to test this kind of tools in the months to come.
references
Les temps de parcours : Définition, méthodes d'estimation, utilisation opérationnelles et
procédés d'affichage, CETE du Sud-Ouest, Dossier du CERTU n°138, Octobre 2002, 206
pages.
Temps de parcours, CETE du Sud-Ouest, dossier du CERTU, janvier 2002, 157 pages.
Application des systèmes de positionnement satellitaire à l'analyse des déplacements,
opportunité de mise en oeuvre, CETE Méditerranée, décembre 2006,
http://www.cete-mediterranee.fr/tt13/www/article.php3?id_article=96
Développement d'un prototype de base de données temps de parcours par GPS, ASP Burbant
& ASP Crosnier, stagiaires de l'Ecole de l'air au CETE Méditerranée, 2007, 81 pages.
http://www.cete-mediterranee.fr/tt13/www/IMG/pdf/stageEA-BDTPGPS-0307.pdf
Cahier des clauses techniques particulières, logiciel de gestion de données temps de parcours
GPS, CETE Méditerranée, juin 2007, 9 pages.
http://www.cete-mediterranee.fr/tt13/www/article.php3?id_article=133
Similar
Mean Average earnings for 2014-15 All GP practices are required to
Mean Average earnings for 2014-15 All GP practices are required to