Somerset and Union Counties

An Analysis of aTaxi Trip Distribution in Somerset and Union Counties, New Jersey

ORF 467: Transportation Systems Analysis

By Natalie Carthy and Chandler Gay

Somerset County, New JerseyFacts:

• Population*: 324,893

• Area (sq. miles): 305

• Census Blocks*: 5,595

• Largest City: Somerville

• Major Employers: AT&T, Johnson & Johnson, Met Life

* Population and Census Block Data from US Census Bureau, 2011. Other Information from Wikipedia and Somerset County Business Partnership Source: “Somerset County,

New Jersey” – Wikipedia

Top 10 Pixels in Somerset County

Somerset Overview

The histogram below shows the distribution of trip lengths throughout an entire day of Somerset County departures.

93%

Trip Breakdown

IntrapixelWalkTrainaTaxi

Pixel {129, 240} – Somerset County, North Plainfield

Item Value

Activity Locations

19

Employment

628

Population 129

School Enrollment

0

Cumulative aTaxi Surplus Throughout the Day• This pixel exemplifies the

typical behavior seen in Somerset aTaxi surplus:• Type 1 taxis are slow to

accumulate a surplus until just after the morning commute at which point the surplus begins to rise at a steeper but constant rate

• Type 2 taxis exhibit the same behavior in the opposite direction: the shortage starts out low but becomes increasingly larger at a constant rate at the same time Type 1 changes.

Pixel {112, 240} – Somerset County

Warren, Chubb Group

Item Value

Activity Locations

5

Employment

3,394

Population 70

School Enrollment

0Chubb Group of Insurance Companies

Cumulative aTaxi Surplus Throughout the Day• This pixel exhibits a more

unique behavior• Type 1 aTaxis exhibit

typical behavior as seen in Somerset.

• Type 2 aTaxis, however, hold a surplus throughout the work day, which we do not see in other pixels.

• This could be explained by Chubb Group employees living in the same neighborhoods, leading to more ride share potential.

Total Somerset County aTaxi Surplus

Deficit indicates that optimized repositioning of aTaxis returning from foreign counties will be very important in minimizing empty vehicle miles will be higher

Total Somerset County aTaxi Surplus

Union County, New JerseyFacts:

• Population*: 539,494

• Area (sq. miles): 105

• Census Blocks*: 7,563

• Largest City: Elizabeth

• Top Employers: Merck & Co., New England Motor Freight, USI Services Group

* Population and Census Block Data from US Census Bureau, 2011, Other Information from Wikipedia

Source: “Union County, New Jersey” – Wikipedia

Top 10 Pixels in Union County

Union Overview

The histogram below shows the distribution of trip lengths originating in Union.

89%

Trip BreakdownIntrapixelWalkTrainaTaxi

Item Value

Activity Locations

210

Employment

7,176

Population 4,025

School Enrollment

2,169

Pixel {150, 244} - Union CountyElizabeth Station (NJTransit)

150 150.5 151244

244.5

245

workhomeschool

Cumulative aTaxi Surplus Throughout the Day

• This pixel exemplifies the behavior seen in most of the other Union pixels:• Type 1 taxis have a

relatively continuous increase in their surplus throughout the day, with a jump around 8 AM due to the morning commute.

• Type 2 taxis exhibit mixed behavior: initially there is a shortage before the morning commute, at which point a quick surplus accumulates, and then a relatively steady increase in the shortage with a jump around the evening commute.

Pixel {150, 243} - Union County

Union County College & Jail

Item Value

Activity Locations

139

Employment

19,010

Population 4,895

School Enrollment

179

150 150.5 151243

243.5

244

workhomeschool

Cumulative aTaxi Surplus Throughout the Day

• This pixel shows irregular Union aTaxi behavior :• Type 1 aTaxi surplus is

normal.

• Type 2 taxis, however, accumulate a large surplus coinciding with the morning commute, which is partially relieved by the evening commute.

• This could be explained by Union County College students living in concentrated areas, leading to more ride share potential.

Total Union County aTaxi Surplus

Total Union County aTaxi Surplus

Vehicle Assignment Algorithm

• Proceeding through the day, for each trip that appears:1) Check if an aTaxi of proper size is waiting at that pixel2) Check if there is an aTaxi of proper size with a destination

of that pixel and an ETA of less than 5 minutes Note: this could be a taxi being repositioned from a foreign

destination or a regular intracounty trip

3) Check if there is an empty taxi waiting less than 5 minutes away that is not on the clock for another departure.

4) Otherwise, “create” a new taxi Here, “create” means that a taxi would have been waiting from the

beginning of the day that has not yet been used but was placed there during the midnight repositioning

Union Repositioning Regions

Somerset Repositioning Regions

Empty Vehicle Repositioning

• For the approximately 5% of the total trips that are intracounty, we assume that the aTaxi stays at its destination for simplicity.

• For the other ~95% that are intercounty trips, barring a return trip within 10 minutes, the aTaxis return to the region of highest import, where:

Approximation of aTaxi Needs

• Theoretical minimum Determined by number of aTaxis on trips at

all times throughout the day• Theoretical maximum

Assume that foreign return trips are rare Let all aTaxis in foreign destinations return to

their domestic origin pixel (no repositioning optimization)

Max determined by the number of aTaxis on the road at all times throughout the day, including the aTaxis returning from foreign counties

Union - Minimum aTaxis

Union - Maximum aTaxis

Union – Expected aTaxi Supply

Minimum aTaxis

Required

Maximum aTaxis

Required

Expected # of aTaxis

Required

Type 1 6,680 9,986 8,500

Type 2 41,445 72,523 57,000

Type 3 2,014 2,449 2,250

Type 4 256 284 275

Somerset - Minimum aTaxis

Somerset - Maximum aTaxis

Somerset – Expected aTaxi Supply

Minimum aTaxis

Required

Maximum aTaxis

Required

Expected # of aTaxis

Required

Type 1 11,236 17,428 14,500

Type 2 24,821 42,152 34,000

Type 3 1,900 2,019 2,000

Type 4 127 127 127