David Boyce
Feb. 5, 2002

Description of Delaware Valley Regional Planning Commission (DVRPC) Data

The DVRPC data were provided by Dr. W. Thomas Walker, Manager, Office of Corridor/Systems Planning, Delaware Valley Regional Planning Commission, Philadelphia, PA, and are released with his permission.

The origin-destination data file (Philadelphia.trips) contains 24 hour flows (vehicles/day) between the 1525 zones in the DVRPC region.  All entries are integer.  The year of the estimated/predicted flows is unknown.  The total flow is 18,503,872 vehicles per day.  Of this flow, 14,336,062 vehicles per day are interzonal flows.

The road network file (Philadelphia.net) contains records for the road network for an unknown year.  The fields of each record are as follows:

1. from node
2. to node
3. capacity (24 hour)
4. length (miles)
5. free flow travel time (minutes)
6. speed (entries do not correspond to free flow speeds, and meaning is unknown)
7. toll
8. link type

The link types are as follows:

1. freeway, including freeway to freeway ramps
2. parkway
3. principal arterial
4. secondary arterial
5. unused
6. collector/local
7. approach link, including centroid connectors
8. ramp
9. dummy link

The road network consists of 13,389 nodes and 40,003 one-way links.  Because of software capacity limitations, some links are coded with an implicit assumption of no U-turns.  This coding convention did not appear to cause a problem in our use of the network, even though our code (OBTAIN) does not check for such coding.

The network was applied in a Build vs. No-Build comparison of the effects of a pair of freeway-to-freeway ramps.  These ramps are included in Philadelphia.net as follows:


from	to	capacity		length		free-flow time

18177	13346	16,575	veh/day	0.80 miles	1.48 minutes  (I-295 EB to NJ 42 SB)

13345	13388	16,575	veh/day	0.82 miles	1.48 minutes	(NJ 42 NB to I-295 WB)

To solve the traffic assignment problem without these ramps, it is advised to set the free-flow travel time to a large number, such as 99.99 minutes.  In this way, the effect of the network coding on the solution is maintained in both solutions.






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