Intersection Improvement Study Hendricks Avon, Indiana Final Report November 7, 2003 Prepared for The Town of Avon By DLZ Indiana, LLC 36 South Pennsylvania Street, Suite 360 Indianapolis, Indiana 46204 317-633-4120
TABLE OF CONTENTS SECTION I: BACKGROUND INFORMATION... 1 PURPOSE OF STUDY... 1 PROJECT AREA... 1 EXISTING AND PROJECTED TRAFFIC... 2 SECTION II: ALTERNATIVES... 4 NO-BUILD ALTERNATIVE... 4 Right-of-Way...4 Traffic Operations...4 Cost...4 Additional Auto Capacity...4 Accommodation of Driveway Access...5 Bicycles and Pedestrians...5 Safety...5 Aesthetics...5 RECONSTRUCTED TRAFFIC SIGNAL ALTERNATIVE... 5 Geometry...5 Right-of-Way...6 Traffic Operations...6 Cost...6 Additional Auto Capacity...6 Accommodation of Driveway Access...6 Bicyclists and Pedestrians...7 Safety...7 Aesthetics...7 MODERN ROUNDABOUT ALTERNATIVE... 7 Geometry...7 Right-of-Way...8 Traffic Operations...9 Cost...9 Additional Auto Capacity...9 Accommodation of Driveway Access...10 Bicyclists and Pedestrians...10 Safety...10 Aesthetics...10 Future Considerations...10 SECTION III COMPARISON OF ALTERNATIVES... 12 Right-of-Way...12 Traffic Operations...12 Cost...12 Additional Auto Capacity...12 Accommodation of Driveway Access...13 Pedestrians and Bicyclists...13 Safety...13 Aesthetics...13 SECTION IV: RECOMMENDATION... 15 Intersection Improvement Study November 7 2003 i
SECTION V: REFERENCES... 16 LIST OF TABLES Table 1: Existing and Projected Intersection Traffic Volumes... 2 Table 2. Level of Service Criteria For Signalized Intersections... 3 Table 3. Roundabout Geometry... 8 Table 4. Alternative Evaluation Matrix (for year 2025)... 14 LIST OF FIGURES Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Project Area and Location Map Existing C.R. 100 S. / Dan Jones Rd. Intersection Reconstructed Traffic Signal Alternative Two-Lane Modern Roundabout Alternative Conceptual Rendering of Modern Roundabout Alternative APPENDICES Appendix A Appendix B Appendix C Synchro Output for Existing, 2025 No Build and 2025 Reconstructed Traffic Signal Alternatives RODEL Outputs for the 2025 Roundabout Alternative Estimate of Probable Design, Construction Costs and Operation Costs Intersection Improvement Study November 7 2003 ii
SECTION I: BACKGROUND INFORMATION PURPOSE OF STUDY The Hendricks Intersection Improvement Study is sponsored by the Town of Avon, Indiana. This report compares the benefits and costs of two intersection improvement alternatives with the benefits and costs of retaining the existing intersection without any improvements. The two improvement alternatives that were evaluated are a reconstructed traffic signal alternative and a modern roundabout alternative. PROJECT AREA The project is located within the Town of Avon in eastern Hendricks County, Indiana (Figure 1). The Town of Avon was incorporated in November of 1995 and has experienced rapid population growth over the past 10 years. A major cause of this growth has been the expansion of the Indianapolis metropolitan area, which has brought significant residential and commercial growth to Avon. The resulting traffic demands have caused extensive delay and congestion on roads like Dan Jones Rd. and C.R. 100 S., which were designed as rural roads. Both Dan Jones Rd. and C.R. 100 S. are important links within the Town of Avon and both are designated as Urban Minor Arterials within the Avon Thoroughfare Plan. Dan Jones Rd. is a primary north/south route through Avon, with a bridge over the east/west CSX rail line approximately 3500 feet north of the study intersection. Dan Jones Rd. is a two-lane roadway with one travel lane in each direction, 2-foot gravel shoulders and open drainage in the project vicinity. An entrance to the CSX Transportation Avon rail yard is also located on Dan Jones Rd., immediately south of the railroad overpass. C.R. 100 S. is an east/west road that serves as an alternate route to the congested U.S. 36 (Rockville Road) for traffic commuting to and from Indianapolis. C.R. 100 S. is a two-lane roadway with one travel lane in each direction, 2-foot gravel shoulders and open drainage in the project vicinity. There are no sidewalks along either road. The intersection of the two roads is currently controlled by a traffic signal, with no auxiliary turn lanes on any approach. Land use in the project area is a mixture of residential and agricultural. The northeast corner of the intersection is being used as cropland, a residential development exists on the southwest corner, and the parcels on the northwest and southeast corners are currently vacant. Pine Creek Elementary school is just northwest of the intersection. There are two school entrance drives on C.R. 100 S., approximately 375 feet and 940 feet west of Dan Jones Rd. There is also one school entrance drive on Dan Jones Rd., approximately 790 feet north of C.R. 100 S. Clark s Creek flows generally north/south through the project area and crosses under C.R. 100 S. approximately 440 feet east of the Dan Jones Rd. intersection. The C.R. 100 S. bridge over Clark s Creek (Hendricks County Bridge 241) was constructed in 1991. It is a concrete box beam bridge with a span of 24 feet and a width of 36 feet. Intersection Improvement Study 1 November 7 2003
EXISTING AND PROJECTED TRAFFIC Existing (year 2003) traffic counts for the intersection of C.R. 100 S. and Dan Jones Rd. were provided by the Town of Avon. The data included morning and afternoon peak hour traffic volumes for each individual turning movement (e.g., through movement, left turn, right turn) at the intersection. The Morning peak hour is from 7:00 to 8:00 a.m., and the afternoon peak hour is from 5:00 to 6:00 p.m. Projected Year 2025 morning and afternoon peak hour traffic volumes were developed for the intersection. These projections were based on information obtained from the Avon Thoroughfare Plan, the Indianapolis Metropolitan Planning Organization, and a recent traffic impact study for the Wellington residential development, which is proposed to be located south of C.R. 100 S. and east of Dan Jones Rd. 2007 peak hour volume forecasts were used from the Wellington traffic impact study. 2025 peak hour volume forecasts were then developed based on an assumed annual traffic volume growth rate of 0.5 percent from 2007 to 2025. Unadjusted output from the Indianapolis Metropolitan Planning Organization travel demand model showed an annual growth rate of 0.32 percent for average daily traffic volumes between 2006 and 2025. Table 1 shows the existing and forecast AM and PM peak hour turning movement volumes for the intersection. Table 1: Existing and Projected Intersection Traffic Volumes AM Peak Hour Eastbound Westbound Northbound Southbound Total (7-8 a.m.) L T R L T R L T R L T R 2003 Existing 1 171 223 59 40 40 41 15 433 48 41 491 33 1635 2007 Forecast 2 321 668 128 97 164 161 36 570 94 98 668 26 3031 2025 Forecast 3 351 731 140 106 179 176 39 624 103 107 731 28 3315 PM Peak Hour Eastbound Westbound Northbound Southbound Total (5-6 p.m.) L T R L T R L T R L T R 2003 Existing 1 48 79 29 52 207 112 40 506 37 44 607 144 1905 2007 Forecast 2 185 259 97 105 663 341 61 754 68 122 773 183 3611 2025 Forecast 3 202 283 106 115 725 373 67 825 74 133 846 200 3949 1 2003 existing counts collected by Traffic Engineering, Inc. on February 19, 2003. 2 2007 Forecast from transportation impact study for Crossman Communities Wellington Development, Edwards & Kelcey, July 2003. 3 2025 Forecast based on assumed 0.5% annual growth in traffic from 2007 to 2025. The Synchro 5 software package was used to determine the Highway Capacity Levels of Service (LOS) for the intersection during the morning and afternoon peak hours using the methods of the Transportation Research Board Highway Capacity Manual, 2000 Edition. The LOS is a quantitative measure that describes the quality of operating conditions within the traffic stream and the perception of motorists. The LOS of an intersection is based on the total delay experienced by vehicles waiting to travel through the intersection. The LOS is based on a scale of A to F, with A being the best situation. A study of this intersection conducted in 2000 indicated that it operated at an LOS B during both the morning and afternoon peak hours. Existing signal timing data could not be obtained from the Town in Intersection Improvement Study 2 November 7 2003
order to verify this LOS. However, significant queuing was observed at the intersection on various occasions during the Summer of 2003, which indicates that the current LOS may actually be lower than B. A peak hour LOS D is typically considered the minimum acceptable operating condition at an intersection Table 2 describes the specific LOS criteria for signalized intersections. Detailed Synchro software output is provided in Appendix A. Table 2. Level of Service Criteria For Signalized Intersections LOS Average Delay (Seconds/Vehicle) Description A < 10 Most vehicles do not stop at all B > 10 and < 20 More vehicles stop than for LOS A C > 20 and < 35 The number of vehicles stopping is significant, although many pass through without stopping D > 35 and < 55 Many vehicles stop. Individual cycle failures are noticeable E > 55 and < 80 Considered being the limit of acceptable delay. Individual cycle failures are frequent F > 80 Unacceptable delay Source: Transportation Research Board, Highway Capacity Manual, 2000 Intersection Improvement Study 3 November 7 2003
SECTION II: ALTERNATIVES This section describes the three alternatives considered as part of this study and presents the results of the analysis performed for these alternatives. A comparative matrix has also been included at the end of this section to highlight the major differences among the alternatives. NO-BUILD ALTERNATIVE The No Build Alternative is intended to represent baseline conditions against which the benefits and impacts of the other alternatives can be compared. The No Build Alternative includes no improvements to the existing intersection. However, traffic volumes are anticipated to increase in the project area between now and 2025 as identified in Section I. The No Build Alternative is the existing signal-controlled intersection with year 2025 traffic volumes. Right-of-Way No additional ROW would be required for the No Build Alternative. Traffic Operations Traffic operations for the No Build Alternative were analyzed using the year 2025 peak hour traffic volumes from Table 1. With optimized signal timing but no geometric improvements, the No Build Alternative would provide an AM peak hour LOS of F. In addition, northbound, eastbound and southbound traffic volumes would exceed the capacity of those approaches by a significant amount. This means that vehicle queues and delays would continue to grow over the peak hour. During the PM peak hour, this alternative would also have an LOS of F, with volumes greatly exceeding capacity on all approaches. Appendix A includes the Synchro output data files for this traffic signal analysis. Cost There is no direct construction cost associated with the No Build Alternative, as the No Build Alternative does not include improvements to the intersection. However, the cost attributable to lost time due to delays and other indirect costs are substantial and will increase as conditions worsen. The annual operating cost of the no build alternative was estimated to be $1,690. This would include costs for periodic routine maintenance for the traffic signal, signs and pavement markings, as well as trouble calls for malfunctioning signal equipment. Operational costs also include the cost of electricity for the traffic signal. A breakdown of these costs is included in Appendix C. The annual operating costs for the no build alternative traffic signal do not include the cost for replacement of the traffic signal hardware, which would be necessary approximately 15 years after their initial installation. Additional Auto Capacity This alternative does not have additional auto capacity because it is already predicted to operate at LOS F. Intersection Improvement Study 4 November 7 2003
Accommodation of Driveway Access The existing driveway configuration would be maintained. All driveways are reasonably accommodated under the No Build Alternative. Bicycles and Pedestrians The existing intersection has no separate bicycle or pedestrian accommodations. Pedestrians would continue to use the roadway shoulders or grass right-of-way. Cyclists would continue to use the roadway travel lanes. Pedestrian and bicycle traffic is currently low, but safety could become more of a concern as residential development continues in the vicinity and as traffic congestion increases. Safety The No Build Alternative would not provide any safety improvements for the project area. Intersection crashes are likely to increase and safety is likely to decrease as traffic volumes and congestion at the intersection increase. Aesthetics The No Build Alternative would not have any scenic impacts, but it would also not provide new opportunities for aesthetic enhancements. RECONSTRUCTED TRAFFIC SIGNAL ALTERNATIVE The Synchro traffic modeling software was used to determine the required geometric and traffic operational characteristics of a reconstructed traffic signal alternative that would accommodate the year 2025 peak hour volumes with an acceptable peak hour LOS. Geometry To accommodate the projected 2025 volumes with acceptable peak hour LOS would require reconstructing the intersection to provide two through lanes plus left and right turn lanes on all approaches. Figure 3 shows the configuration of this reconstructed traffic signal alternative. This alternative was developed based on a design speed of 45 mph (posted speed is 40 mph) on both roads. The design vehicle was a WB-62 truck (18-wheel Interstate tractor trailer), and it was assumed that about two percent of vehicles would be trucks. It was assumed that the reconstructed roadway would have a curb and gutter drainage system, as called for in the typical urban arterial section in the Avon Thoroughfare Plan. This would minimize ROW acquisition and impacts associated with roadside ditches. Due to the extent of roadway widening necessary, this alternative would require the replacement or widening of the existing C.R. 100 S. bridge over Clark s Creek. In addition, the existing sanitary lift station on the northeast corner of the intersection would need to be relocated to accommodate the roadway widening. Auxiliary turn lane lengths at the reconstructed intersection were determined using the procedures of Section 46-4.02(02) of the Indiana Department of Transportation Design Manual. Auxiliary through lane lengths were determined using the procedures of Section 46-7.0 of the Indiana Department of Transportation Design Manual. When widening a two-lane road to accommodate additional through lanes at an intersection, long transition distances are typically required both upstream and downstream of the intersection. These transition distances are required (1) to ensure safe and efficient merging of traffic into a single lane downstream of the intersection and (2) to encourage full use of both through lanes by traffic. Intersection Improvement Study 5 November 7 2003
The usage of additional through lanes that are only provided for short distances at intersections is typically very low, resulting in the loss of much of the intersection capacity. Many drivers are reluctant to use short auxiliary through lanes because they know they will have to immediately merge back into the primary travel lane and will be perceived as cutting in the queue. Right-of-Way ROW would need to be acquired in order to reconstruct the traffic signal. ROW is required for the expanded intersection including turn lanes and lane tapers. A total of approximately 124,600 square feet (2.86 acres) of permanent ROW would need to be acquired to construct this alternative. One home in the southeast quadrant would need to be acquired for this alternative. In addition, the existing sanitary lift station on the northeast corner would require relocation. The existing earth berm on the southwest corner is likely to be impacted significantly as it runs along C.R. 100 S. The ROW requirements would need to be refined during project design. Traffic Operations Using the year 2025 peak hour traffic volumes from Table 1, traffic operations for the intersection were analyzed. With optimized signal timing, the reconstructed traffic signal alternative would provide an AM peak hour LOS of B with an average of 16.7 seconds of delay per vehicle. During the PM peak hour, this alternative would have LOS B with an average of 19.5 seconds of delay per vehicle. Appendix A includes the Synchro output data files for the traffic signal analysis. Cost The cost of the reconstructed traffic signal alternative is estimated to be approximately $3.40 million (year 2003 dollars). This would include design and construction of all road improvements shown in Figure 3, replacement of the C.R. 100 S. bridge over Clark s Creek, relocation of the sanitary lift station, adding a traffic signal and lighting, ROW acquisition, drainage improvements, landscaping, and sidewalk. Actual costs could change as the project is designed. A more detailed breakdown of this cost estimate is included in Appendix C. The annual operating cost of the reconstructed traffic signal was estimated to be $2,290. This would include costs for periodic routine maintenance for the traffic signals, signs and pavement markings, as well as trouble calls for malfunctioning signal equipment. Operational costs also include the cost of electricity for the traffic signals and lighting. A breakdown of these costs is included in Appendix C. The annual operating costs for the reconstructed traffic signal do not include the cost for replacement of the traffic signal hardware, which would be necessary after approximately 15 years. Additional Auto Capacity The reserve capacity of this alternative was calculated at 27 percent. This means that peak hour traffic volumes at the intersection could increase by approximately 27 percent beyond the 2025 AM peak hour traffic projections in Table 1 before the intersection would reach LOS E or approach volumes would exceed capacity. Accommodation of Driveway Access All driveways near the intersection would be reasonably accommodated by this alternative. Impacted drives would be reconstructed to meet INDOT standards, but no drives would Intersection Improvement Study 6 November 7 2003
require relocation. If a new driveway were constructed to access Dan Jones Rd. from the parcel on the northwest corner of the intersection, this driveway would need to allow right-in, right-out access only because of its proximity to the intersection Bicyclists and Pedestrians New sidewalks along C.R. 100 S. and Dan Jones Rd. would be incorporated into the reconstructed traffic signal alternative (Figure 3). Pedestrian crosswalks and curb ramps would be provided at the intersection. The traffic signal would include pedestrian signal indications and pushbuttons. Bicycles would be accommodated in the vehicle traffic lanes. Safety This alternative would improve safety in the project area relative to what would be experienced without improvements at the intersection. However, crashes would likely still increase as traffic volumes at the intersection continue to increase. Aesthetics The traffic signal alternative would result in scenic impacts to the corridor as a result of widening the intersection with additional asphalt surface. Installation of sidewalk, curb and gutter, decorative lighting, and decorative mast arm signal poles would reflect the growing suburban character of the vicinity. Relocation of the existing sanitary lift station would also provide an aesthetic enhancement. MODERN ROUNDABOUT ALTERNATIVE An analysis of the intersection was performed using the roundabout modeling software RODEL for the year 2025 peak hour volumes to determine the required geometric characteristics for a modern roundabout. This information was used to prepare a conceptual roundabout design for the intersection. This concept balances a number of important factors including traffic operations, safety, ROW acquisition, and cost. Geometry Modern roundabout geometry is influenced by a variety of factors related to traffic operations and safety considerations. Roundabout geometry is used to control the speed at which motorists can enter and exit an intersection. There are two speed regimes considered when designing a roundabout: (1) speeds during peak hours when traffic volumes are highest and motorists stay within designated lanes, and (2) speeds during off-peak hours when the occasional motorist ignores lane markings and negotiates the roundabout at the highest possible rate of speed. After detailed analysis and design work, the modern roundabout proposed for the C.R. 100 S./Dan Jones Rd. intersection was developed. This roundabout is shown in Figure 4, and relevant geometric parameters are summarized in Table 3. The proposed design (Figure 4) includes a roundabout with two-lane entries on both Dan Jones Rd. approaches and the eastbound C.R. 100 S. approach, and a two-lane entry with a right turn bypass lane on the westbound C.R. 100 S. approach. The roundabout was located to the greatest extent practical to minimize ROW impacts, to avoid impacting the berm in the southwest quadrant of the intersection, and to avoid the C.R. 100 S. bridge over Clark s Creek. Preliminary coordination was undertaken regarding the roundabout s location with staff from the Town of Avon to address these constraints. Construction of the roundabout Intersection Improvement Study 7 November 7 2003
would require relocation of the existing sanitary lift station on the northeast corner of the intersection. Table 3. Roundabout Geometry Component Southbound Eastbound Northbound Westbound Entry Width (curb face to curb face)* 26.3 ft 26.3 ft 26.3 ft 26.3 ft Number of Entry Lanes 2 2 2 2 Flare Length 395 ft 395 ft 330 ft 165 ft Inscribed Circle Diameter (ICD) 197 ft 197 ft 197 ft 197 ft Entry Radius 82 ft 82 ft 82 ft 82 ft Entry Angle 30 20 30 30 Half Width 12 ft 12 ft 12 ft 12 ft Number of Exit Lanes 2 2 2 2 *Entry widths include travel lanes and gutters (i.e., they are measured curb face to curb face). All legs of the roundabout include two entering and two exiting lanes. Each leg drops one lane downstream of the roundabout exits to tie into the existing road, which has one lane in each direction (Figure 4). The taper used for these lane drops is appropriate for the speeds at which vehicles will be exiting the roundabout (approx. 20-25 mph). The entry and exit lanes will be divided by a splitter (deflector) island. Splitter islands serve many purposes as they provide shelter for pedestrians, assist in controlling speeds, separate approaching and exiting traffic, guide traffic into the roundabout at the correct angle, and help deflect out-ofcontrol vehicles so that they do not enter the roundabout at a right angle to circulating traffic. Splitter islands are also used to accommodate signs. As in the Reconstructed Signal Alternative, the design vehicle used for the roundabout was a WB-60 (18-wheel tractor trailer). This vehicle can be accommodated on all turning movements at the roundabout. A truck apron about 15 feet wide will be required in the central island to accommodate left turns by this vehicle (Figure 4). It was assumed that all four legs of the roundabout would have a curb and gutter drainage system, as called for in the Thoroughfare Plan. All of the curbs used for the roundabout should be non-mountable except around the central island. The central island curb should be mountable to accommodate large trucks (WB-62) making left turns, but it should be high enough to discourage passenger vehicles (e.g., sport utility vehicles) from driving over it. This assures that motorists will not drive over curbs in an attempt to increase the speed at which they negotiate the intersection. In addition, the non-mountable curb on the splitter islands would help deflect out-of-control vehicles so that they do not enter the roundabout at a right angle to circulating traffic. This lessens the possibility of serious crashes. Right-of-Way In order to construct the modern roundabout alternative, ROW would need to be acquired from properties near the intersection. ROW is required not only for the roundabout, but to construct the approach and exit lanes and tapers. Attempts were made during the concept development to minimize ROW impacts to the greatest extent possible without impacting the operation or safety of the roundabout. A total of approximately 58,800 square feet (1.35 Intersection Improvement Study 8 November 7 2003
acres) of ROW would need to be acquired to construct the roundabout. Most of the roundabout will be located in the northeast quadrant of the existing intersection (Figure 4). This alternative would also require ROW acquisition in the other quadrants as well. It is possible that some of these ROW impacts could be reduced during the design phase if this alternative is selected for construction. No structures would be impacted for the construction of the modern roundabout. However, the existing sanitary lift station on the northeast corner would require relocation. Traffic Operations The RODEL analysis showed that the modern roundabout would provide LOS A in year 2025 for the AM peak hour, with an average delay per vehicle of 8.2 seconds. The year 2025 PM peak period is estimated to have an average delay per vehicle of approximately 7.3 seconds, which is also LOS A. This analysis was developed for the 50 percent confidence level for capacity (i.e., the capacity that is most likely to occur at the intersection). The roundabout alternative was also tested at the 85 percent confidence level (i.e., a pessimistic capacity), and this test showed that the roundabout would still provide acceptable traffic operations for this scenario in 2025 (LOS B with average delay of 14.2 seconds for the PM peak hour and LOS B with average delay of 17.1 seconds in the AM peak hour). RODEL output summary sheets are included in Appendix B. As a type of unsignalized intersection, the LOS criteria used for modern roundabouts are similar to those used for signalized intersections, except slightly more strict. Table 2 shows the LOS thresholds for all types of unsignalized intersections. Cost The estimated cost of the modern roundabout alternative is approximately $2.20 (year 2003 dollars). This would include design and construction of all road improvements shown in Figure 4, ROW acquisition, lighting, drainage improvements, landscaping, and sidewalks. All costs have been estimated conservatively. The actual cost of this alternative may change once a more detailed investigation is performed during the design phase, especially with regard to the vertical curve to the north of the intersection. A more detailed cost breakdown is included in Appendix C. The annual operating costs of the modern roundabout was estimated to be $2,340. These include costs for periodic maintenance (e.g., pavement markings, mowing, and signage) and the cost of electricity for lighting. A breakdown of these costs is also included in Appendix C. Additional Auto Capacity Additional analysis was performed to determine how much excess capacity the proposed roundabout would have. Construction of the modern roundabout would provide about 18 percent reserve auto capacity at the intersection. This means that traffic volumes at the intersection could increase by approximately 18 percent beyond year 2025 AM peak hour volumes before the intersection would reach LOS E. The future addition of right turn bypass lanes on the eastbound and southbound approaches, if needed, would provide the roundabout with about 27 percent reserve capacity beyond the 2025 AM peak hour volumes. Although these bypass lanes would have additional cost and ROW impacts, they could be accommodated by the proposed design if they are ever needed. Intersection Improvement Study 9 November 7 2003
Accommodation of Driveway Access The modern roundabout alternative would reasonably accommodate all driveways. Although this alternative reasonably accommodates existing driveways, it does result in minor changes to residential driveways. If a new driveway were constructed to access Dan Jones Rd. from the parcel on the northwest corner of the intersection, this driveway would need to allow right-in, right-out access only because of its proximity to the intersection. Those wishing to travel north would make a U-turn around the roundabout. Full-access drives could be allowed at all other locations. Bicyclists and Pedestrians New sidewalks along C.R. 100 S. and Dan Jones Rd. would be incorporated into the modern roundabout alternative (Figure 4). It is recommended that bicycles should not circulate within a roundabout. Instead, they should use pedestrian crossings at the roundabout. As long as bicyclists avoid circulating inside the roundabout, they would be safely accommodated by this alternative. Modern roundabout intersections accommodate pedestrians safely. However, it should be noted that in parts of the U.S., some visually impaired pedestrians have stated that they are concerned about their ability to safely cross at modern roundabout intersections with heavy traffic volumes and relatively slow speeds. Therefore, some blind pedestrians may have difficulties crossing independently at modern roundabout intersections. Safety Properly designed modern roundabouts are very safe, and crashes would likely be reduced relative to what would occur without improvements to the intersection or with the traffic signal alternative. Due to their low circulating speeds, deflection at entry, and yield-controlled entrances, modern roundabouts are substantially safer than intersections controlled by traffic signals, traffic circles, and stop signs. Studies from around the world have found that modern roundabouts typically reduce crashes by 40 to 60 percent compared to stop signs and traffic signals. They also typically reduce injury crashes by 35 to 80 percent and almost completely eliminate incapacitating injury and fatal crashes. A comprehensive recent U.S. study (Insurance Institute for Highway Safety 2000) is consistent with these results. Aesthetics The modern roundabout alternative would provide opportunities for aesthetic enhancement. These opportunities would come from the green space in the splitter islands and the central island. A conceptual rendering of the modern roundabout alternative is shown in Figure 5. The drawing shows how this alternative could be landscaped to improve the aesthetics of the intersection. Roundabouts are often used as gateway improvements for communities. In these instances, the central island of the roundabout can contain a variety of features to enhance the roadway. Future Considerations The roundabout alternative has been designed so that future widening of C.R. 100 S. or Dan Jones Rd. could be accommodated without changes to the intersection. While the approaches and exits would need to be altered to tie into the roundabout, changes would not be needed inside the splitter islands. If and when these roads are ever widened, care should be taken to assure that the road designs do not negatively affect the roundabout s traffic operations or safety. This would entail an analysis and design by persons knowledgeable Intersection Improvement Study 10 November 7 2003
about roundabouts. This is especially important relative to speed control and capacity on the approaches. In addition to these considerations, if traffic volumes increase beyond those expected or capacities are lower than those predicted, right turn bypass lanes could be added on the eastbound and southbound approaches to provide improved traffic operations. Although these bypass lanes would have additional cost and ROW impacts, they could be accommodated by the proposed design if they are ever needed. Intersection Improvement Study 11 November 7 2003
SECTION III COMPARISON OF ALTERNATIVES In order to compare the alternatives, several criteria were considered. All of the criteria are directly related to benefits and impacts of the alternatives and are quantified where possible. Table 4 includes a summary of the results of this comparison. Right-of-Way ROW will be required for both of the build alternatives (i.e., the reconstructed traffic signal alternative and the modern roundabout alternative). Approximately 2.86 acres of ROW are needed for the reconstructed signal alternative, and 1.35 acres are needed for the modern roundabout. The reconstructed traffic signal alternative would also require acquisition of a home in the southeast quadrant of the intersection. Both alternatives would require relocation of the existing sanitary lift station on the northeast corner of the intersection. It is anticipated that the signal alternative would have a significant impact on the existing earth berm on the southwest corner of the intersection but the roundabout alternative would have only a minor impact on this berm. Traffic Operations The traffic operations of the two build alternatives for the year 2025 peak hour volumes are both acceptable (LOS D or better). However, the LOS of the modern roundabout (LOS A) is better than the reconstructed traffic signal alternative (LOS B), and it has a lower average vehicle delay. Even with pessimistic assumptions of driver behavior at the roundabout, its traffic operation is still better than the traffic signal. Cost The reconstructed traffic signal alternative would cost about $1.2 more to construct than the roundabout alternative in year 2003 dollars ($3.40 million vs. $2.20 million). This difference is mainly due to the length of new road that needs to be constructed for the two alternatives. The reconstructed traffic signal alternative requires longer taper lengths for the additional intersection approach lanes and thus does not tie back into the existing road as quickly as the roundabout alternative. The reconstructed traffic signal alternative therefore requires more new roadway than the roundabout alternative. Because of this, the reconstructed traffic signal alternative would also require that the C.R. 100 S. bridge over Clark s Creek be widened. This difference can be seen in Figures 3 and 4. These planning level cost estimates will need to be further refined and adjusted during the design phase of the project. In addition to construction costs, annual operational cost of the alternatives were estimated. These costs were estimated to be approximately the same for both alternatives ($2,290 for the signal alternative vs. $2,340 for the roundabout alternative)..landscape maintenance and lighting costs would likely be somewhat higher for the roundabout, but these additional costs would be more than offset by the savings in traffic signal maintenance and electricity costs. In addition, the traffic signal hardware would require replacement within approximately 15 years after initial construction. This cost is not included in the annual maintenance cost. Additional Auto Capacity The reconstructed traffic signal alternative provides about 27 percent reserve auto capacity at the intersection, while the modern roundabout provides about 18 percent reserve auto capacity. This means that the traffic signal would have a greater safety buffer for handling traffic beyond the 2025 projections than the roundabout configuration currently proposed. With the addition of right turn bypass lanes for the eastbound and southbound approaches, Intersection Improvement Study 12 November 7 2003
the roundabout could also accommodate approximately 27 percent more traffic than the 2025 forecast. This would require additional ROW and construction cost, but would not require significant reconstruction of the roundabout. Accommodation of Driveway Access Both the modern roundabout and traffic signal accommodate all existing driveways around the intersection (Figures 3 and 4). No drives would require relocation under either alternative. Impacted driveway approaches would be reconstructed to meet INDOT standards. Any new drive onto Dan Jones Rd. from the vacant parcel on the northwest corner would need to be right-in, right-out under the either the alternative, but U-turns can be accomplished easily with the roundabout. Pedestrians and Bicyclists The modern roundabout alternative would accommodate pedestrian crossings more safely than the traffic signal alternative. Studies have found that pedestrian-related crashes are reduced by 30 to 40 percent (relative to other types of intersection control) and are much less serious at modern roundabouts. This is due to lower travel speeds and the fact that pedestrians need only cross one direction of traffic at a time, using splitter islands as a refuge. However, it should be noted that in parts of the U.S., some blind pedestrians have stated that they are concerned about their ability to safely cross at modern roundabout intersections with heavy traffic volumes and relatively slow speeds. Therefore, some visually impaired pedestrians may have difficulties crossing independently at modern roundabout intersections. The two build alternatives would have similar operations for bicycles as long as they avoid circulating within the roundabout. Safety The roundabout would result in about half the injury crashes that would be experienced with a traffic signal. Properly designed modern roundabouts are substantially safer than traffic signals due to their low circulating speeds, reduced number of conflict points, and deflection at entry. Generally, converting from a four-leg signalized intersection to a four-leg modern roundabout will reduce the number of conflict points from 32 (traffic signal) to eight (modern roundabout). Converting to a modern roundabout will also reduce the speed of vehicles entering the intersection. This will reduce the potential for high speed crashes and injury crashes at the intersection. Studies have clearly demonstrated that properly designed modern roundabouts typically reduce total crashes by 40 to 60 percent compared to stop signs and traffic signals. They also typically reduce injury crashes by 35 to 80 percent and almost completely eliminate incapacitating injury and fatal crashes (Insurance Institute for Highway Safety, 2000). Based on this information, the modern roundabout alternative will have the best safety performance out of the three alternatives. Aesthetics The modern roundabout alternative provides a better opportunity for aesthetic enhancements, as landscaping and other amenities can be placed within the central island and splitter islands where they do not interfere with required lines of sight. The exact locations where landscaping is allowable would be determined during the design phase of the project. Intersection Improvement Study 13 November 7 2003
Table 4. Alternative Evaluation Matrix (for year 2025) Evaluation Criteria Comments No Build Reconstructed Traffic Signal Modern Roundabout Amount of new ROW and 2.86 Acres 1.35 Acres Right-of-Way/Relocations required relocations required to construct None 1 home and sanitary lift station sanitary lift station the alternative. Future Traffic Operations (2025) Planning-Level Construction Cost Estimate Operational Costs Additional Auto Capacity Accommodation of Driveway Access Bicyclists and Pedestrians Safety Aesthetics Average delay per vehicle and LOS for AM and PM peak hours for the year 2025. Includes cost for design, construction, construction inspection, and ROW acquisition. All costs are in year 2003 dollars. Approximate cost of ongoing operations including electricity (lighting), signal adjustment, bulbs/other equipment, mowing, pavement markings, etc. Amount (%) that year 2025 peak hour auto traffic could increase before the intersection would reach LOS E. Assumes a proportional increase of all entering volumes simultaneously. Rating of how well the proposed intersection will accommodate existing driveway access. Rating of the mobility, safety, and impacts on bicyclists and pedestrians of the proposed intersections. Based on recent U.S. studies. Potential impacts to the scenic qualities near the intersection and opportunities for aesthetic enhancements. Demand Exceeds Capacity LOS = F AM Delay = 16.7 sec / LOS = B PM Delay = 19.5 sec / LOS = B AM Delay = 8.2 sec / LOS = A PM Delay = 7.3 sec / LOS = A Daily savings of >20 vehicle-hours of delay by 2025 compared to reconstructed traffic signal. $0 $3.40 Million $2.20 Million Approximately $1,690 per year Approximately $2,290 per year Approximately $2,340 per year No change to driveways. No changes to pedestrian or bicycle facilities. n/a 27% Slight increase in crashes relative to existing condition as congestion and volumes increase. No impacts to existing scenic qualities. Moderate opportunity for aesthetic enhancement. All driveways reasonably accommodated. Possible minor impacts to some new driveways. Pedestrians and bicyclists safely accommodated. Lower crash rate than no build due to signal, lane and lighting improvements. Significantly higher crash rate and severity than roundabout. Moderate scenic impacts from increased pavement area. Limited opportunities for aesthetic enhancements in remaining ROW. 18% with initial configuration. 27% with added bypass lanes. All driveways reasonably accommodated. Possible minor impacts to some new driveways. Pedestrians safely accommodated; Bikes safely accommodated as long as they do not use circulating roadway. Minor concerns related to visually impaired pedestrians. Up to 60% fewer total crashes, 80% fewer injury crashes, and 90% fewer fatalities than reconstructed signal intersection. Minor scenic impacts. Several aesthetic opportunities will result from the construction: addition of green space and the opportunity for increased landscaping. Intersection Improvement Study 14 November 7, 2003
SECTION IV: RECOMMENDATION Upon reviewing the impacts and benefits of the three alternatives considered, DLZ recommends the modern roundabout alternative as the best long-term solution at this location. This recommendation is based on the following key distinctions: The roundabout would provide better traffic operation, with less than half of the peak hour intersection delay of the reconstructed traffic signal. The roundabout would provide a safer intersection, with up to 60% fewer crashes and up to 80% fewer injury crashes than the reconstructed traffic signal. The roundabout would cost approximately $1.2 million less to construct than the reconstructed traffic signal. The roundabout would require less than half of the new ROW that the reconstructed traffic signal would require and would not require purchase of a home. The roundabout alternative would have lower impacts to scenic qualities and would provide more opportunities for aesthetic enhancements than the reconstructed traffic signal alternative. If the roundabout alternative is advanced into the design phase, a few important issues will need to be evaluated. First, proposed landscaping treatments should be developed in a way that does not interfere with required sight distances. Second, driveway access details will need to be worked out with property owners. Finally, vertical stopping sight distances on the intersection approaches will need to be verified to assure they are adequate. Intersection Improvement Study 15 November 7, 2003
SECTION V: REFERENCES American Association of State Highway and Transportation Officials. 1994. A Policy on Geometric Design of Highways and Streets. Washington, D.C. Edwards & Kelcey. July 2003. Wellington Traffic Impact Study. Prepared for Crossman Communities. Insurance Institute for Highway Safety. 2000. Crash Reductions Following Installation of Roundabouts in the United States. Arlington, VA. The Schneider Corporation. July 14, 1999 (revision). Avon Thoroughfare Plan. Transportation Research Board. 2000. Highway Capacity Manual. Washington, D.C. Federal Highway Administration. Washington, D.C. No Date. Your community deserves a lot less Intersection Improvement Study 16 November 7, 2003
Appendix A - Synchro Outputs for Year 2025 Traffic Signal Alternative
Appendix B RODEL Outputs
RODEL Output for Year 2025 AM Peak Hour ******************************************************************************** * * * 18:8:2003 155 AVON INDIANA 2 LANER 1 BYPASS 50p AM PEAK 7539 * * * ******************************************************************************** * * * * E m 8.00 8.00 8.00 8.00 * TIME PERIOD min 90 * * L' m 120.00 120.00 100.00 50.00 * TIME SLICE min 15 * * V m 3.60 3.60 3.60 3.60 * RESULT PERIOD min 15 75 * * RAD m 30.00 30.00 30.00 30.00 * TIME COST pnd/hr 1.00 * * PHI d 30.00 20.00 30.00 30.00 * FLOW PERIOD min 15 75 * * DIA m 60.00 60.00 60.00 60.00 * RULE left/right RIGHT * * G. SEP 0 0 0 0 * CONFID. LEVEL % 50 * * * * ******************************************************************************** * NAME *PCU * FLOWS (1st exit 2nd etc..u) *FLOF*CAPF* FLOW RATIO *FLO TIME* * * * * * * * * *SB DJONE*1.05* 28 731 107 0 *1.00*1.00*.75 1.125.75*15 45 75* *EB CR100*1.05* 140 731 351 0 *1.00*1.00*.75 1.125.75*15 45 75* *NB DJONE*1.05* 103 624 39 0 *1.00*1.00*.75 1.125.75*15 45 75* *WBCR100 *1.05* -176 179 106 0 *1.00*1.00*.75 1.125.75*15 45 75* * * * * * * * * * * * * * * * * * * * * * * * * ******************************************************************************** * * * * FLOW v 866 1222 766 285 * GLOBAL DELAYS * * CAPACITY v 1994 1633 1397 1412 * * * DELAY Lane1 s 3.6 14.3 6.8 4.8 * VEH HRS 7.5 * * DELAY Lane2 s 3.6 14.3 6.8 4.8 * * * DELAY Lane3 s ---- ---- ---- ---- * AVE DEL 8.2 secs * * DELAY Lane4 s ---- ---- ---- ---- * * * MAX LANE Q v 1 4 1 1 * * * * * ********************************************************************************
RODEL Output for Year 2025 PM Peak Hour ******************************************************************************** * * * 18:8:2003 155 AVON INDIANA 2 LANER 1 BYPASS 50p PM PEAK 7540 * * * ******************************************************************************** * * * * E m 8.00 8.00 8.00 8.00 * TIME PERIOD min 90 * * L' m 120.00 120.00 100.00 50.00 * TIME SLICE min 15 * * V m 3.60 3.60 3.60 3.60 * RESULT PERIOD min 15 75 * * RAD m 30.00 30.00 30.00 30.00 * TIME COST pnd/hr 1.00 * * PHI d 30.00 20.00 30.00 30.00 * FLOW PERIOD min 15 75 * * DIA m 60.00 60.00 60.00 60.00 * RULE left/right RIGHT * * G. SEP 0 0 0 0 * CONFID. LEVEL % 50 * * * * ******************************************************************************** * NAME *PCU * FLOWS (1st exit 2nd etc..u) *FLOF*CAPF* FLOW RATIO *FLO TIME* * * * * * * * * *SB DJONE*1.05* 200 846 133 0 *1.00*1.00*.75 1.125.75*15 45 75* *EB CR100*1.05* 106 283 202 0 *1.00*1.00*.75 1.125.75*15 45 75* *NB DJONE*1.05* 74 825 67 0 *1.00*1.00*.75 1.125.75*15 45 75* *WBCR100 *1.05* -373 725 115 0 *1.00*1.00*.75 1.125.75*15 45 75* * * * * * * * * * * * * * * * * * * * * * * * * ******************************************************************************** * * * * FLOW v 1179 591 966 840 * GLOBAL DELAYS * * CAPACITY v 1604 1530 1776 1361 * * * DELAY Lane1 s 11.7 5.7 4.8 8.6 * VEH HRS 8.0 * * DELAY Lane2 s 11.7 5.7 4.8 8.6 * * * DELAY Lane3 s ---- ---- ---- ---- * AVE DEL 7.3 secs * * DELAY Lane4 s ---- ---- ---- ---- * * * MAX LANE Q v 3 1 1 1 * * * * * ********************************************************************************
Appendix C Estimate of Probable Design, Construction and Operation Costs
Intersection Improvement Study Summary of Estimated Construction Costs Cost Item Reconstructed Signal Roundabout Roadway Improvements $ 1,168,200 $ 779,600 Sidewalk & Curb Ramp $ 116,700 $ 92,000 Traffic Signal $ 75,000 $ - Traffic Signs, Marking & Lighting $ 36,600 $ 52,000 Sodding & Landscaping $ 25,800 $ 46,600 Drainage $ 218,200 $ 137,800 Relocate Sanitary Lift Station $ 150,000 $ 150,000 Replace Bridge over Clark's Creek $ 282,000 $ - Subtotal $ 2,072,500 $ 1,258,000 Contingency (15%) $ 310,900 $ 188,700 Total Construction Cost $ 2,383,400 $ 1,446,700 Construction Inspection $ 357,500 $ 217,000 Right-of-Way $ 397,700 $ 289,300 Design $ 259,900 $ 246,300 Total Project Cost $ 3,398,500 $ 2,199,300
Intersection Improvement Study Summary of Estimated Routine Annual Costs Cost Item No Build Reconstructed Signal Roundabout Electricity Signal 1 $ 740 $ 240 $ - Lighting 2 $ - $ 340 $ 440 Maintenance Signal 3 $ 890 $ 890 $ - Road & Signs 4 $ 60 $ 100 $ 100 Landscaping 4 $ - $ 720 $ 1,800 Total Annual Cost $ 1,690 $ 2,290 $ 2,340 1 Based on electricity at $0.63 per watt per year, the rate paid by the City of Indianapolis. 2 Based on 4 150-watt lights for signal or 4 250-watt lights for roundabout. Annual electric rates were estimated using rates paid by the City of Indianapolis. 3 Based on current signal maintenance rate of $74 per month. 4 Costs estimated by DLZ. Reconstructed Traffic Signal Wattage Calculation (Assumes all signal heads are LED) Item Number Wattage per Item Total Wattage 3-section head 5 15 75 5-section head 3 30 90 pedestrian head 8 15 120 cabinet 1 100 100 Total 385 Existing Trafffic Signal Wattage Calculation (Assumes all signal heads are incandescent) Item Number Wattage per Item Total Wattage 3-section head 8 135 1080 cabinet 1 100 100 Total 1180