NEW JERSEY DEPARTMENT OF TRANSPORTATION

Improvements to Signal Systems to Reduce Delays

RACM Analysis

Michael Baker Jr., Inc. Signal Systems - 1

Control Measure:

Delays at signalized intersections can be exasperated by poor signal timings and 

poor signal coordination that results in the increased likelihood of waiting at a red 

light. Much of this delay involves high-emission idling and as such improvements 

to signal operations by installing networked systems, centralized controllers and 

properly adjusting timings can yield measurable air quality benefits.

Description:

Many of the signalized intersections within the state of New Jersey work 

independently of adjoining signals. Also, most signals are not adjusted as local 

conditions change. This leads to increased waiting and delays at signals which 

in turn results increases idling emissions from vehicles. Through proper signal 

coordination and timing, delays can be reduced statewide leading to some 

improvement in regional air quality.

To analyze the impact of improving traffic signal operations, the New Jersey 

Congestion Management System (NJCMS) and specifically its intersection delay 

model was employed. The NJCMS using both actual and inferred signal data to 

estimate the additional delay associated with traffic signals. The NJCMS models 

signal progression on a scale of 1-5: 1 being detrimental signal progression, 3 

neutral and 5 being very beneficial progression. For the purposes of this 

investigation, the signal progression throughout the state was set to 4 except for 

those intersections already coded as 5. 

Methodology:

The NJCMS analysis for this project considers all the signals coded in the 

NJCMS databases. Tables 1 through 4 show these results county by county and 

by non-attainment area.

The entire amount of delay was assumed to be idling delay. Idling emission 

rates were developed from multiple runs of MOBILE 6.2 using appropriate local 

inputs. Idling emissions rates were developed for both the summer and winter 

seasons. Total delay reduced was proportioned by the number of days in each 

season and multiplied by the appropriate emission rate(s) to get total emissions 

reduced by season. The sum of the seasonal emissions was used for total 

annual emissions. The daily emissions benefit was calculated by dividing the 

winter season emissions by the number of days in that season.

For the RACM analysis it was acknowledged that some signals are already 

coordinated and that not all signals can be improved within the timeframe of this 

analysis. As such, only 5% of the estimated benefits were considered which

represents improvements to approximately 262 intersections.
NEW JERSEY DEPARTMENT OF TRANSPORTATION

Improvements to Signal Systems to Reduce Delays

RACM Analysis

Michael Baker Jr., Inc. Signal Systems - 2

Results: Typical Summer Day/Annual Emissions

Benefits (Emission Reductions Due to Reduced Queuing):

Emission Reductions (Statewide):

Pollutant

Type

Analysis Year 2009

Tons/Day Tons/Year

VOC 0.0206 -

NOx 0.0100 2.5012

PM2.5 - 0.3949

SO2 - 0.0148

Ozone Analysis – Daily Benefits in New Jersey

Benefits 

(Reductions)

Ozone Non-Attainment Area

New York-N. New 

Jersey-Long Island,

NY-NJ-CT

PhiladelphiaWilmington-Atlantic City

PA-NJ-MD-DE

VOC (Tons/Day) 0.0137 0.0070

NOx (Tons/Day) 0.0061 0.0039

PM2.5 Analysis – Annual Benefits in New Jersey

Benefits 

(Reductions)

PM2.5 Non-Attainment Area

New York-N. New 

Jersey-Long Island,

NY-NJ-CT

PhiladelphiaWilmington

PA-NJ-DE

NOx (Tons/Year) 1.6215 0.4347

PM2.5 (Tons/Year) 0.2728 0.0571

SO2 (Tons/Year) 0.0100 0.0023

Cost/Benefit Analysis

Total costs were estimated as follows:

- Each Intersection signal improvement costs approximately $150,000 for a new 

controller

- 262 intersections will be improved, 61 in DVRPC, 201 in NJTPA
NEW JERSEY DEPARTMENT OF TRANSPORTATION

Improvements to Signal Systems to Reduce Delays

RACM Analysis

Michael Baker Jr., Inc. Signal Systems - 3

- Total Cost of Project: $39,300,000

- $9,150,000 in DVRPC

- $30,150,000 in NJTPA

Cost/Benefit Results

Pollutant

Cost/Benefit for Each Pollutant

Ozone* PM 2.5

NY-NJ-CT PA-NJ-DEMD NY-NJ-CT PA-NJ-DE

VOC ($/Ton/Day) $8,824,796 $5,261,373 - -

NOx ($/Ton/Day) $19,671,426 $9,447,267 - -

NOx ($/Ton/Year) - - $18,593,836 $21,050,557

PM2.5 ($/Ton/Year) - - $110,540,716 $160,261,760

SO2 ($/Ton/Year) - - $3,007,187,722 $3,977,593,189

*Daily Costs used in calculation of cost/benefit ratio are Annual costs divided by 250