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The concepts described in the previous chapter represent a series of choices about future transportation. These choices focus on the following considerations:

1. Extending major road accessibility to more areas of the county in coordination with the Will County Land Resource Management Plan.
2. Increasing the traffic capacity of the system.
3. Achieving a more unified system of roads via an increase in interagency coordination.
4. Protecting right-of-way opportunities, even though the need or financial resources for new transportation facilities cannot be discerned at this time.
5. Supporting the enlargement of the public transportation system in the face of current trends toward increasing auto usage.

The above factors represent choices about basic transportation policy for Will County. The three transportation concepts were evaluated in this chapter in terms of these policies. Further, from a physical planning perspective, locations and alignments were evaluated relative to the input of new facilities on land use and the environment. As a long-range framework plan, the level of detail is limited, with an attempt to avoid any major negative impacts.

Information is provided to summarize the likely performance, impact, and capital cost of the three transportation concepts. Each concept focused on one method for meeting the future transportation needs of the county, such as enhancing the current transportation network, providing new expressway facilities, and upgrading the arterial street system with and without the addition of a third regional airport. Each of the three transportation concepts consists of a number of highway and arterial street improvements that were developed to meet the expected transportation needs of the county.

The purpose of the evaluation task is not to select one of the three transportation networks, but to test which transportation concepts are most appropriate for the different regions of the county. For instance, the results of the evaluation could have shown that the extension of I-355 to the Indiana state line and the widening of arterials in the Peotone area were the most efficient method of serving regional demand generated by the potential third airport, as well as improving travel time in the central and eastern sectors of the county. But the results could also have shown that completing the arterial grid network, building new river crossings, and correcting roadway misalignments are the most appropriate means for meeting the transportation needs for intracounty travel in the western half of the county. With this in mind, the concepts were compared on a local and a regional basis to determine which combination of network elements would satisfy the expected transportation demands most efficiently.

The framework for evaluating regional transportation plans is defined in the goals and objectives statement. Among other criteria established in the goals and objectives are guidelines provided in the Transportation Efficiency Act for the 21st Century (TEA-21) and the 1990 Clean Air Act Amendments (CAAA). Though Will County's 2020 transportation plan is a subregional evaluation and therefore not required to meet the criteria set forth in TEA-21, the TEA-21 criteria that emphasize transportation efficiency and air quality are important considerations in the evaluation process.

The three concepts were each evaluated for their performance according to traffic engineering criteria, environmental impacts, and capital costs, as described in the transportation goals and objectives (see Chapter 3).

Objectives and Criteria

The goal of the evaluation is to expose the differences between the three transportation system concepts and the individual projects. In this sense, some criteria were more appropriate for evaluating the systemwide benefits of an overall approach, such as upgrading the arterial street system; other criteria were used to evaluate the impact of specific projects at the local level. For instance, the evaluation of the vehicle-miles-traveled (VMT) per capita is most appropriate on a regional level, whereas an environmental impact criterion, such as new route-miles in residential developments, is most relevant to the local community.

The criteria used included estimated daily traffic volumes, volume-to-capacity ratios, travel time, vehicle-miles, vehicle-hours, speed, alignment impact measures (displacement, penetration into sensitive areas, land-use disruption), and capital cost. Overall, no priority was given to either systemwide or site-specific evaluation measures. By exposing the differences between the different approaches shown in each concept, the county should be in a better position to discuss the impacts and trade-offs associated with each solution.

To focus on geographically oriented performance and impacts, five subareas have been examined in detail:

The northwest subarea, including DuPage and Wheatland Townships, is by far the highest-growth area of the county. This area experiences congestion on the major arterial facilities, which is expected to worsen significantly as a result of future development. The previous (1984) county transportation plan recommended capacity improvements on Boughton Road, realignment of Weber Road at Naperville Road, and the extension of 95th Street to Boughton Road, none of which have been completed. The implementation of these improvements, among others, will be more urgent in the near future than during the planning horizon of the 1984 plan.

Commercial and residential growth in the west central townships of Plainfield, Lockport, Troy, and Joliet has contributed to an increase in roadway congestion on the state highways and river crossings linking the urban centers (Joliet, Plainfield, Lockport, Romeoville, and Crest Hill) with each other and with the interstate system. U.S. Route 30, IL 59, IL 53, and the IL 7 and Ruby Street bridges are presently congested, and congestion is projected to become significantly worse.

Suburban growth in the north central townships of Homer, New Lenox, and Frankfort will put increasing demand on the arterial network linking the Frankfort/Mokena/New Lenox area with Joliet, the employment corridor in eastern DuPage County, and southwest Cook County. The projected near doubling of traffic on I-80 will increase traffic levels on parallel east-west routes such as U.S. Route 30, U.S. Route 6, 159th Street, Laraway Road, and St. Francis/LaPorte Road. The potential extension of I-355 from I-80 to I-57 would provide some relief for traffic congestion on I-80 and U.S. Route 30.

Residential and commercial growth in the east townships of Monee and Crete will require increased capacity on the key north-south routes connecting Will County with Chicago and the regional interstate system. A potential growth explosion in the Peotone area could occur if the proposed South Suburban Airport is developed. Major airport access considerations would include expansion of expressway facilities, including I-57 and IL 394, an interstate connector along the north side of the airport, and improvements to most of the state highways and arterial facilities in the area.

While growth is anticipated in the southwest subarea, principally in and around the City of Wilmington, few roadways are projected to experience congestion in the planning horizon of this document. A new or improved river crossing would satisfy the key constraint in the system.

Information Sources

In order to undertake the evaluation, information on travel demand, physical conditions, and capital cost was assembled from several different sources.

Performance Evaluation

The three concepts, including the number of lanes and posted speed limit for each improved roadway or new alignment, were submitted to the Chicago Area Transportation Study (CATS). Based on socioeconomic forecasts developed by the Northeastern Illinois Planning Commission (NIPC) for the year 2020, traffic assignments were developed for each concept by CATS. The traffic assignment model outputs, including the traffic volumes, network capacity, volume-to-capacity relationships, and travel time information, as well as manual and automatic traffic counts performed by Barton-Aschman, formed the basis of data used in the performance evaluation.

Land Use and Environment

Land use data was provided by Will County and was supplemented by information provided by the municipalities and information from Barton-Aschman's files. Project-specific environmental impact data, such as lost acres of farmland and new alignment penetration into natural areas and residential areas, were determined from 1993 aerial photographs provided by Will County based on potential alignment corridors identified by Will County. Systemwide environmental impacts, such as air quality and other VMT impacts, were calculated using the traffic assignment model outputs. Data from the 1990 census and 2020 projected population and employment statistics were provided by NIPC.

Capital Cost

Capital cost data was calculated from quantities determined for each improvement, based on potential alignment corridors approved by Will County for new and improved roadways. Unit costs for construction were based on recent construction cost information in the Chicago area and costs being used for state highway projects. Right-of-way and dwelling unit acquisition costs were provided by Will County. The financial feasibility of the concepts was determined by comparing the order-of-magnitude costs of the various concepts with the expected funding available from the county and other (federal) sources.

Assumptions/Planning Factors

As part of the evaluation analysis process, a series of basic assumptions were made and planning factors considered, as listed below:

Regional roadway system remains constant outside of Will County (committed projects are included).

No major changes to the regional transit system will be made other than line extensions and new line development; same primary mode use levels (auto versus transit) will continue.

No major energy or environmental shifts will occur.

Travel demand management program effects are not included in the demand model relative to traffic volumes (especially peak-hour traffic).

Constant 1998 dollars are used for capital cost estimates.

Only aerial photograph level of detail has been applied to the evaluation of new alignments; this is consistent with the fact that this is a planning study, not a design project.

The traffic assignment model does not include the impact of potential new developments, such as industrial parcels on the former Joliet Arsenal property or major recreational venues such as the Joliet motorsports facilities, since such projects are not yet reflected in the official NIPC forecasts.

Evaluation Analysis Results

The evaluation results have been organized into five categories of impact. The first addresses the estimated transportation implications on a systemwide basis. The second focuses on the transportation implications by subarea. The third discusses the location impacts associated with potential improvement projects and possible environmental and land-use impacts. The fourth addresses air quality impacts, and the fifth deals with capital cost and possible financial resources.

System-Level Transportation Implications

Year 2020 base traffic estimates were prepared for conditions with and without a new regional airport. These forecasts indicate a large increase in traffic. During the next 20-plus years, traffic volumes will double on most major roads. Significant traffic growth will be especially true for the major roadways in the northwest quadrant of the system and in the eastern section of the county surrounding the proposed site of the South Suburban Airport. Overall, it is estimated that vehicle miles of travel will increase by between 87 and 102 percent for the without airport and with airport scenarios, respectively. The portion of the network operating at over capacity (congested) conditions would increase from 18 percent to approximately 50 percent. Average speeds would drop by 18 percent (to 32 mph) for the without airport scenario and by as much as 39 percent (to 24 mph) for the with airport scenario.

The three concepts were developed to address the shortages and deficiencies associated with the 2020 base systems. On the basis of the presumed additions to capacity, each network was examined to assess its ability to serve year 2020 traffic.

Using these estimates, the performance of each concept has been analyzed and evaluated. The results of the evaluation are summarized by a set of overview statistics comparing the alternative street systems, followed by comparisons that focus on subareas of the county. These subareas provide a means to consider more specific transportation issues that are geographically oriented to certain areas of the county and are not systemwide concerns.

Tables 9 and 10 describe overall systemwide conditions. Table 9 summarizes estimated future traffic volumes by "screenlines." Screenlines are cross sections of the system at significant locations to demonstrate how well each concept would perform. Table 10 provides overall system statistics concerning vehicle-miles and hours of travel.

Key observations on the screenline data in Table 9 are as follows:

1. The greatest travel demand increase (existing to year 2020) would occur across screenline G if the proposed South Suburban Airport is developed. A tripling of traffic between Cook County and Will County could occur as a result of the development implications associated with the airport.
2. Travel demand increases in the north-south direction across the DuPage County line, in the east-west direction across the Cook County line, and in east-west intracounty travel across the Des Plaines River were shown to more than double over the next 20 years.
3. The approved extension of I-355 between I-55 and I-80 contributes significantly to the over 100 percent increase in traffic volumes across screenlines A, B, C, and D.
4. The increased capacity provided by the additional river crossings included in Concept 2 (Caton Farm Road and 127th Street) would increase vehicular travel across the river by approximately 37,000 vehicles per day. Without these new river crossings, this traffic will either use alternative routes across the river or trips will be altered to avoid a river crossing. This increase reflects the capacity constraint that would be experienced if no additional bridges are built.
5. For Concept 3, the extension of I-355 to I-65 in Indiana would increase travel demand across the state line by up to 70,000 vehicles per day in 2020. This large increase would be associated with the attraction of longer-distance trips to I-355 and the use of I-355 to access the proposed South Suburban Airport. Without this interstate connection, most of this travel demand would remain on I-80.

Table 9 - Traffic Volumes by Screenlinea
Screenline Position	From	To	1995 Existinga	2020 Basea without Airport	Concept 1	Concept 2	2020 Basea with Airport	Concept 3
A S of DuPage County	US Rt 30	Lemont Rd	167.5	365.9	330.1	372.8	340.7	320.1
B N of I-55	US Rt 30	Lemont Rd	135.2	292.8	302.7	321.6	265.9	291.9
C Des Plaines River	135th St. Bridge	Ruby St. Bridge	52.3	87.0	95.7	123.7	83.0	83.6
D N of Renwick Rd/IL 7	IL 59	Gougar Rd	159.5	323.5	331.8	339.4	274.1	292.1
E E of Bell Road	143rd St	US Rt 6	32.2	82.5	81.9	82.3	72.2	70.1
F W of Harlem Ave	I-80	Laraway Rd	97.1	199.0	196.7	196.2	190.9	181.5
G S of Steger Rd	I-57	IL 394	124.5	235.0	239.3	235.5	337.8	411.9
H N of Theodore St.	U.S. Rt 30	Broadway St	63.5	83.8	88.9	93.9	70.8	71.5
a Traffic volumes are existing or estimated average annual daily traffic (AADT) volumes in units of 1,000 vehicles per day. Existing volumes were obtained from IDOT (1995 AADT Traffic Map for Will County and the Transportation Systems Center), ISTHA, and CATS (Will County Transportation Plan Model Veq Forecasts). Notes: Screenline A is in an east-west direction to examine north-south trips. Screenline B is in a southwest-northeast direction to examine north-south trips. Screenline C is in a north-south direction to examine east-west trips and in an east-west direction to examine north-south trips. Screenline D is in an east-west direction to examine north-south trips. Screenline E is in a north-south direction to examine east-west trips. Screenline F is in a north-south direction to examine east-west trips. Screenline G is in an east-west direction to examine north-south trips. Screenline H is in an east-west direction to examine north-south trips.

Key findings on the system-level statistics in Table 10 are as follows:

1. Future travel demand, as indicated by vehicle-miles of travel (VMT) would increase by 85 to 106 percent over the next 20 years.
2. All concepts improve conditions over 2020 base (existing-plus-committed projects only) conditions, as there would be fewer congested vehicles miles of travel under the three scenarios than under 2020 base conditions. Concept 2, which includes the largest number of capacity improvement projects, but does not address impacts related to the proposed third airport, would result in the greatest reduction of travel on congested roadways. Most major roadways would operate under capacity if all of the Concept 2 improvements were implemented.

3. The average speed under all concepts would also be higher than under 2020 base conditions, but would be approximately 10 percent lower than under existing conditions, as capacity improvements will not keep pace with the increase in travel demand. Concept 3 would have the highest average speed due to the I-355 extension to I-65 and major expressway improvements.

4. As a result of development growth farther into the unincorporated areas of the county, the per capita vehicle miles of travel will increase over existing conditions, even with the transportation improvements. This reflects longer trip lengths on average.

5. Per capita vehicle hours of travel would increase over existing conditions from 15 to 25 percent, reflecting longer travel times due to longer trips and/or more travel on congested roadways.
6. While it is difficult to differentiate between concepts at this level of comparison, Concept 2 would add the most traffic capacity, with the fewest congested roadways. However, it is also the most expensive concept (when not considering the costs associated with the I-355 extension), with the highest cost efficiency ($0.08 million per 1,000 incremental VMT per day) and the lowest cost-effectiveness (11.79 VMT per day per $1 million).

Table 10 - SYSTEM-LEVEL MEASURES
	Existing	2020 Base without Airport	Concept 1	Concept 2	2020 Base with Airport	Concept 3
VMT (1,000s)	19,559	36,578	36,296	36,598	39,575	40,426
Daily VHT (1,000s)	502	1,129	1,074	1,024	1,661	1,119
CGVMT Percent	18.4	49.5	44.9	31.0	53.8	36.7
Excess VMT	541	3,900	3,349	2,321	4,653	2,804
System Speed	39.0	32.0	33.8	35.7	23.8	36.1
Daily VMT per	46.5	50.3	49.9	50.3	48.5	49.5
Daily VHT per	1.19	1.55	1.48	1.41	2.03	1.37
New or Improved Miles Without I-355 Extension	--	--	227.0	461.0 446.0		403.0 366.0
Capital Cost ($M) Without I-355 Extension	--	--	830.0	2,021.0 1,445.0	--	2,705.0 1,225.0
Incremental VMT	--	--	16,737	17,039	--	20,867
Incremental VHT	--	--	572	522	--	617
Cost Efficiency: $Millions of Capital Cost per Incremental VMT ($M/1,000 VMT) Without I-355 Extension	--	--	0.05	0.12     0.08		0.13     0.06
Cost Effectiveness: Incremental VMT per Capital Cost (1,000 VMT/$M) Without I-355 Extension	--	--	20.17	8.43     11.79	--	7.71     17.03
Notes: 1. Future VMT up by at least 85 percent over existing system. 2. All concepts have less excess VMT than 2020 base conditions. 3. All concepts have a higher average speed than 2020 base conditions; Concept 3 is highest. 4. VMT per capita would be 6 to 8 percent higher than existing conditions; Concept 3 is slightly better than Concepts 1 and 2. 5. Travel times per capita would be 15 to 25 percent higher than existing conditions; Concept 3 would be better. 6. VMT on congested roadways could increase from 68 to 144 percent over existing conditions; Concept 2 is best by far. Glossary of Terms: VMT = vehicle-miles of travel, daily VHT = vehicle-hours of travel, daily CGVMT = percentage of VMT that occurs on congested roadways Excess VMT = the sum of VMT in excess of capacity on each roadway System Speed = average speed of travel in the county Incremental VMT (or VHT) = increase in VMT (or VHT) over existing level

Subarea Transportation Implications

Beyond these system-level observations, a more detailed analysis at the subarea level reveals that the concepts would display significant differences in performance. Table 11 summarizes the average daily traffic volume projections on selected links within the five subareas.

Table 11 - AVERAGE DAILY TRAFFIC VOLUMES ON SELECTED LINKS (traffic volumes in units of 1,000s vehicles per day)
Roadway	1995a Existing	2020 Base without Airport	Concept 1	Concept 2	2020 Base with Airport	Concept 3
Northwest Subarea
IL 59 (south of	12.4	18.2	32.0	30.7	17.4	28.7
Plainfield-Naperville Road (south of 111th Street)	4.3	7.8	5.6	6.6	7.6	5.3
IL 53 (south of	27.5	37.0	34.8	44.1	35.9	34.6
Boughton Road (west	18.0	36.1	33.6	52.6	33.9	32.9
I-55 (east of IL 53)	77.0	156.8	132.3	125.0	148.1	118.8
U.S. Route 30 (east of Kendall County line)	10.2	15.2	15.8	17.0	13.9	15.4
Weber Road (south of	24.9	31.9	43.9	36.9	26.3	33.3
WIKADUKE Trail	N/A	N/A	N/A	13.5	N/A	N/A
135th Street Bridge	N/A	34.2	31.7	17.0	29.4	28.1
127th Street Bridge	N/A	N/A	N/A	28.1	N/A	N/A
West Central
I-80 (bridge over Des	61.0	90.3	88.2	96.4	85.1	85.3
U.S. Route 30 (east of	14.3	16.5	15.4	20.2	15.0	12.4
IL 59 (north of IL 126)	15.1	19.2	33.6	29.0	17.2	30.3
IL 126 (west of U.S.	5.4	10.6	10.9	8.5	8.9	8.7
I-55 (north of U.S.	52.7	98.4	101.7	105.7	87.9	85.7
U.S. Route 30 (east of	11.1	15.6	15.9	16.8	14.4	15.3
Renwick Road (east of	9.2	10.2	19.7	14.0	8.4	20.0
IL 53/IL 7 (south of	25.1	33.2	29.9	34.3	27.4	25.6
State Street Bridge	25.3	25.3	39.0	27.1	22.6	35.5
IL 171 (south of IL 7)	18.4	24.6	24.4	21.9	20.9	20.0
IL 7 (east of Farrell	11.8	15.6	28.0	22.9	14.7	25.5
Caton Farm Road	N/A	N/A	N/A	31.4	N/A	N/A
Houboldt Road Bridge	N/A	N/A	8.5	7.4	N/A	6.5
a Existing traffic volumes based on CATS 1995 estimates. N/A = Not Applicable.
North Central Subarea
IL 7 (west of Cook	12.2	17.8	31.3	29.8	15.8	28.2
U.S. 6 (west of Cook	8.2	12.6	8.7	15.7	11.2	7.9
I-80 (east of U.S.	49.6	103.9	101.2	103.4	101.3	90.1
U.S. Route 45 (north	11.9	32.8	32.3	26.0	38.2	32.1
U.S. Route 30 (west of	17.0	27.8	30.3	27.8	28.2	29.5
Laraway Road (west of	5.7	13.5	13.8	15.1	15.5	9.1
South Suburban Tollway (I-355) (north of IL 7)	N/A	77.2	71.1	84.1	67.9	82.2
East Subarea
I-57 (north of Cook	42.3	83.0	86.1	77.2	107.3	146.7
IL 50 (south of Cook	13.3	25.5	22.4	23.8	37.8	33.7
IL 1 (south of Cook	9.2	18.9	20.3	20.7	27.6	30.2
IL 394 (south of Cook	25.1	38.4	53.3	54.7	46.6	100.1
South Suburban Tollway (I-355) (west of Indiana state line)	N/A	N/A	N/A	N/A	N/A	97.9
Wilmington-Peotone Road (311th Street) (east of I-50)	0.5	1.6	2.0	2.2	9.6	18.3
IL 1 (north of 303rd	8.5	11.7	16.1	16.0	17.2	19.8
Southwest Subarea
U.S. Route 6 (west of	6.9	10.4	8.8	10.1	11.5	10.6
I-55 (south of U.S.	44.1	68.3	65.9	65.2	66.3	56.9
IL 53 (south of	4.4	19.7	18.9	14.4	17.1	5.5
U.S. 52 (south of	9.9	15.9	13.8	11.4	16.6	16.0
U.S. 45 (south of	4.8	11.1	13.1	12.7	14.2	16.7
South Suburban Tollway (I-355) (west of U.S. Route 45)	N/A	N/A	N/A	37.7	N/A	72.7
a Existing traffic volumes based on CATS 1995 estimates. N/A = Not Applicable.

In the northwest subarea, the key issue is roadway capacity on the major north-south and east-west arterials, including I-55, IL 59, IL 53, Weber Road, U.S. Route 30, Plainfield-Naperville Road, Boughton Road, and 95th Street. Key observations include:

1. With the widening of I-55, IL 53, Plainfield-Naperville Road, U.S. Route 30, and Boughton Road, Concept 2 would provide the most roadway capacity and the fewest congested roadways.
2. An additional Des Plaines River crossing at 127th Street (included in Concept 2 only) would provide significant relief for the 135th Street bridge, which would otherwise be the only bridge serving the northwest subarea. Traffic volumes on the 135th Street bridge could be reduced by nearly 50 percent (32,000 down to 17,000 vehicles per day [vpd]) if an additional bridge is constructed.
3. The 2020 base traffic volumes on Weber Road would be lower than for the three concepts. This identifies the impact of the widening of Weber Road to six lanes. That is, the higher-capacity roadway would attract more trips. The base networks would retain the four-lane roadway; with this capacity constraint, more trips would not be attracted. When parallel routes are also improved, such as I-55 and IL 53 (as included in Concept 2), traffic volumes, while still greater than under base conditions, would be reduced by as much as 16 percent than if the parallel routes were not improved (as in Concept 1).
4. The development of the proposed South Suburban Airport would divert or slow the rate of growth in the northwest subarea, resulting in 5 to 15 percent less traffic on the major arterials than if the airport is not developed.

In the west central subarea, the key observations are the need for additional Des Plaines River crossings, bypass routes around the downtown core of Plainfield and Lockport, increased access to I-55, improved capacity on the north-south feeder routes into the Joliet metropolitan area (IL 53, U.S. Route 30, Weber Road, IL 171, and IL 59), and a major north-south arterial serving western Will County and eastern Kendall County.

1. Without any new bridge crossings over the Des Plaines River, the traffic volume on the IL 7 bridge through Lockport would remain approximately 25,000 vehicles per day, which exceeds the efficient capacity of this two-lane bridge. The development of the Caton Farm Road/Bruce Road/IL 7 SRA route (Concept 2), as opposed to the previously considered 159th Street/Renwick Road route, would provide a new river crossing that would offer relief to the IL 7 bridge. Projected traffic volumes on the IL 7 bridge might still increase over the next 20 years, but only by 5 to 10 percent under this concept, as the Caton Farm Road bridge would accommodate the additional cross-river travel demand that will be generated in the Crest Hill/Lockport area (approximately 30,000 vehicles per day). The Ruby Street, 127th Street, and 135th Street bridges would accommodate the remaining river crossing demand across Screenline C in Concept 2 (approximately 40,000 vehicles per day).
2. The Caton Farm Road SRA route would provide a high-capacity, east-west arterial alternate to using Renwick Road through downtown Lockport.
3. The extension of 143rd Street in Plainfield in combination with a new I-55 interchange at 143rd Street would create a downtown Plainfield bypass route for through trips from U.S. Route 30, IL 59, and IL 126. Projected traffic volumes through the Plainfield core area could be reduced by 5 to 10 percent with this improvement.
4. The new I-55 interchange at Caton Farm Road would provide relief to U.S. Route 30, presently the only access route to Plainfield and northwestern Joliet, including the Louis Joliet Mall. Projected traffic volumes on U.S. Route 30 (east and west of the I-55 interchange) could be reduced by as much as 25 percent if a new interchange is constructed at Caton Farm Road.
5. Capacity improvements to IL 59, U.S. Route 30, and Weber Road, in all three concepts, would be effective in providing enough roadway capacity to accommodate projected 2020 traffic demand. However, additional capacity is also required on I-55, IL 53, and IL 171. Only Concept 2 provides this additional capacity.
6. The WIKADUKE Trail is projected to attract from 10,000 to 30,000 vehicles per day along its various segments between I-80 and the DuPage County line. As a parallel north-south route to IL 59, the future SRA route could be effective in reducing the travel demand on IL 59 by up to 10 percent.

For the north central subarea, key observations include the impact of a new tollway in the South Suburban Tollway corridor and access to I-80, as well as roadway capacity on the key travel arteries of I-80, U.S. Route 30, Bell Road, IL 7, Laraway Road, U.S. Route 6, U.S. Route 45, and IL 43.

1. The tollway is projected to attract between 11,000 and 37,000 vehicles per day (vpd) if I-355 is extended only to I-57 (Concept 2) and between 40,000 and 98,000 vpd if I-355 is extended to I-65 and the South Suburban Airport is developed (Concept 3). While many of the vehicles on this facility would represent long-distance trips, the traffic volumes on I-80, U.S. Route 45, and Laraway Road would be affected by the presence of the South Suburban Tollway. Volume reductions on I-80 would be approximately 10,000 vpd under Concept 3, but unchanged under Concept 2. Similarly, Laraway Road volumes show no change under Concept 2, but a reduction of 4,000 to 5,000 vpd under Concept 3. U.S. Route 45 volumes would be reduced by 6,000 to 7,000 vpd under either concept, and U.S. Route 30 volumes appear unchanged under either concept. This could indicate that U.S. Route 30 in the Frankfort/Mokena/New Lenox area is used primarily for local short- and mid-distance trips rather than as a regional route.
2. A new I-80 interchange, possibly at Wolf Road, would improve regional access to Mokena and the developing areas of Orland Park. It could also reduce traffic through the U.S. Route 45 interchange by 10 percent, or approximately 5,000 vehicles per day.
3. Capacity improvements proposed in all three concepts would accommodate projected traffic volumes on IL 7, Bell Road, U.S. Route 30, and U.S. Route 45. However, only Concept 2 would provide the additional lane requirements on I-80, U.S. Route 6, and Laraway Road.

The level of growth in the east subarea is directly dependent on whether the development of a third regional airport goes forward in the Peotone area. Key observations include:

1. The South Suburban Tollway would be effective in removing more than 50,000 daily airport-related vehicle trips from the existing interstate and arterial system in the area (assuming full buildout of the airport by 2020).
2. If no new airport is developed, the Concept 1 widening of IL 1 and IL 394 and a new I-57 interchange at Stuenkel Road will be adequate to accommodate the growth in this region. In addition, the 13-mile section of I-57 (I-80 to Manhattan-Monee Road) will be operating at or over capacity and will need to be widened, which is considered only in Concept 3.
3. The existing arterial system would be overwhelmed if the airport is developed and no improvements are made. Arterial improvements included in Concept 3 would be effective in providing adequate capacity on most arterial routes.

Growth is projected to occur in the southwest subarea at a much slower pace. Key observations include:

1. Under all three concepts, most roadways do not seem to be significantly affected by the changes to the system.
2. The only noticeable difference related to the airport development in the eastern part of the county would be that approximately 20,000 vehicles per day would be diverted from I-55 and IL 53 to an upgraded Wilmington-Peotone Road SRA, Manhattan-Monee Road, and parallel facilities.
3. The most significant capacity issue is IL 53 (Baltimore Street) through Wilmington and over the Kankakee River. Concept 2 includes the widening of the bridge to four lanes to accommodate the 20,000 vpd projected to cross the river at this location in 2020.
4. Growth in the Manhattan area may generate the need to improve U.S. Route 52 between Manhattan and Joliet. Only Concept 2 considers this improvement.

Location Impacts

Since each of the concepts contains a series of transportation improvements, there are various impacts associated with the location or alignment of these projects. As an overall measure of the concepts, Table 12 summarizes several impacts associated with penetration into sensitive areas and displacement of existing residential and commercial land uses. Analysis of the impacts indicates that Concept 2 could engender the worst impacts. These would be related to building displacements because of the numerous roadway widening projects; agricultural land penetration because of the various roadway extensions, including I-355; and natural area penetration from the additional river crossings. Concept 3 also produces significant encroachment on agricultural, residential, and natural areas, most notably because of the extension of I-355 to the Indiana state line.
 

Table 12 - SYSTEM ENVIRONMENTAL IMPACTS
Impact	Measure	Concept 1	Concept 2	Concept 3
Penetration
Agricultural/Farmland	Acres	680	1,260	1,490
Residential Areas	Centerline Feet	24,300	26,850	26,850
Wetlands/Natural Areas	Centerline Feet	15,000	18,700	16,150
Displacement
Residential	Dwelling Units	12	67	8
Commercial	Square Feet (footprint)	0	32,000	0

On a route-specific basis, Table 13 identifies the major potential roadway projects that are incorporated in the concepts. Intersection realignment projects are not included. These projects have been reviewed at the aerial photograph level, supplemented by some field reconnaissance. The alignments chosen are believed to be potentially feasible, although there would be certain significant impacts associated with some of them.
 

Table 13 - POTENTIAL IMPACTS OF ROADWAY IMPROVEMENT PROJECTS
Road	Beginning	End	Concept	Potential Impacts
I-80 widening	U.S. Route 45	I-55	2	--
I-55 widening	Naperville Road	I-80	2	--
I-355 extended	I-80	I-57	2, 3	Major new right-of-way; agricultural land penetration; some wetlands; significant land use planning issues
I-355 extended	I-57	I-65	3	Major new right-of-way; agricultural land penetration; significant land use planning issues
IL 59 SRA widening	I-55	DuPage County line	1, 2, 3	Right-of-way needed in Plainfield, Shorewood; environmental impacts; wetlands
Larkin/Weber/Boughton SRA widening	I-80	IL 53	1, 2, 3	Right-of-way needed; land use disruptions due to widening; traffic impacts on residential areas; wetlands
IL 53 SRA widening	I-55	DuPage County line	1, 2, 3	Traffic impacts on
Plainfield-Naperville Road widening