CDOT Region 6 Communications Study. Bandwidth Analysis Technical Memorandum. Prepared by:

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CDOT Region 6

Communications Study

Bandwidth Analysis

Technical Memorandum

Prepared by:

1515 Arapahoe St.

Suite 500, Tower 1

Denver, CO 80202

303.228.2300

September 22, 2000

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Region 6 Communications Study Page 2

CDOT Region 6 Communications Study

Tech Memo 2

Bandwidth Analysis

Introduction

The CDOT ITS Unit is developing a metrowide communications network to enhance its existing ITS network. The intent of this network is to provide a statewide standard for communications for ITS to meet the growing demand for a statewide system. By providing this standard, both new and existing ITS deployments can be designed to tie into the statewide communications network, thus providing the opportunity to share data and video throughout the Denver metro area.

The objective of this memorandum is to determine the appropriate measures needed to tie the existing and proposed ITS devices to a CDOT facility so that the information can be disseminated to other CDOT information centers and the Traffic Operations Center (TOC). There are five CDOT facilities that can take the incoming information and send it to other facilities. They include: CDOT headquarters, Region 6, Communications Node Building (TMS) #1 and #2, and the TOC. This overall project outlines the necessary actions that will need to be taken to integrate the existing ITS devices throughout the Denver metro area.

To properly design a fully integrated ITS network, the bandwidth requirements for each segment must be identified. The bandwidth requirements will determine the necessary equipment needed to connect the ITS devices, and the fiber needed to accommodate the regional network.

Assumptions

To accurately describe the bandwidth needed to interconnect the existing and proposed devices, assumptions were made about the bandwidth requirements for each device. The assumed bandwidth needed per device is shown in Table 1. These values are conservative to permit future long-term expansion throughout the region.

Table 1.

Assumed Bandwidth Requirements Per Device

For the purposes of this study, all proposed or future equipment was evaluated as if it were existing. This will result in higher bandwidth requirements, giving room for additional growth to new devices as technology in ITS continues to develop.

Device ATR 28.8 kbps CCTV 10000.0 kbps HOV GATES 28.8 kbps HAR STATION 64.0 kbps HAR SIGN 28.8 kbps RAMP METER 28.8 kbps DMS 28.8 kbps Bandwidth

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Bandwidth Analysis

The bandwidth required for each corridor (I-25, I-225, I-70, I-270, US-36, and C-470) was determined from CDOT supplied information including maps, GPS, and other plans and studies. The results of each corridor are shown in Table 2. I-25 was broken into three segments (120th St. to 6th Ave, 6th Ave. to Colorado Blvd., and Colorado Blvd. to Lincoln Ave.).

Table 2

Corridors In Study Area

CDOT Communication Node Building #2

The CDOT Communications Node Building #2, located at I-25 and 70th Avenue, will be responsible for collecting the information transmitted along the OC-3 fiber lines running along U.S. 36 and I-270 (as shown in Figure 1). Any future ITS expansions along these corridors will also go through Node Building #2. Node Building #2 will also be the concentration point for any new devices placed along I-25 north of I-70, especially those north of US-36.

Figure 1.

CDOT Communication Node Building #2 Coverage

Segment Segment Description

I-25 120th Ave. to 6th Ave.

I-25 6th Ave. to Colorado Blvd.

I-25 Colorado Blvd. To Lincoln Ave.

6th Ave Kipling St. to I-25

U.S. 36 Sheridan Blvd. To I-25

C-470 Wadsworth Blvd. To I-25

I-225 I-25 To I-70

I-70 Pecos St. to York St.

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The U.S. 36 corridor requires approximately 40,288 kbps, or 40.3 Mbps. The breakdown of devices along U.S.36 is shown in Table 3. As the U.S. 36 corridor continues to have growth along its frontage, it is expected that additional devices will be installed and the bandwidth requirements will increase proportionately.

Table 3

Bandwidth Requirements along U.S. 36

The I-270 segment is relatively new; thus the level of monitoring is still being developed. This new segment of I-270 allows traffic to go directly from I-70 to U.S. 36. The

bandwidth requirement for the I-270 segment is 20,057.6 kbps, as shown in Table 4. Table 4

Bandwidth Requirements along I-270

The devices on the I-76 segment are shown in the bandwidth requirements of the I-270 corridor.

The existing ITS devices along the north I-25 corridor between I-70 and US-36 use Node Building #1 as the primary concentration point. Node Building #2 was built as a result of the HOV Direct Connect project (ITS Special). Node Building #2, therefore, is intended to serve as the concentration point for all future devices placed along I-25 north of I-70, including those devices deployed as part of the ITS Special project. The bandwidth requirement for the north I-25 segment is 30,028.8 kbps, as shown in Table 5.

Table 5

Future Bandwidth Requirements along I-25

Devices Number of Devices Bandwidth (kbps) ATR 6 172.8 CCTV 4 40,000 DMS 3 86.4 HOV GATE 1 28.8 Total 40,288 Devices Number of Devices Bandwidth (kbps) ATR 2 57.6 CCTV 2 20,000 Total 20,057.6 Devices Number of Devices Bandwidth (kbps) CCTV 3 30,000 DMS 1 28.8 Total 30,028.8

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The total bandwidth required along the corridors that will communicate directly to the CDOT Communication Node Building #2 is 90,374.4 kbps (90.4 Mbps). As the corridor continues to expand, new devices are likely to be placed along I-270 from I-25 to I-70 and along I-76 from I-70 to US-85. The communications along these two corridors will pass through the CDOT Communications Node Building #2.

CDOT Communication Node Building #1

The CDOT Communication Node Building #1 will receive information transmitted from new devices placed along I-25 from I-70 to 6th Avenue, as shown in Figure 2. The devices along I-70 are also included in Node Building #1’s coverage.

Figure 2

CDOT Communication Node Building #1 Coverage

The bandwidth required to serve the northern portion of I-25 is 161,267.2 kbps (161.3 Mbps). The breakdown of the devices that will communicate directly with node building #1 is shown in Table 6.

Table 6

Bandwidth Requirements along I-25 North (Devices Communicating Directly to Node Building #1)

The ITS Special project installed fiber along I-25 to just north of the US-36 interchange. New fiber is required north along the corridor to tie in any new devices.

Devices Number of Devices Bandwidth (kbps) ATR 26 748.8 CCTV 16 160,000 HOV GATE 6 172.8 DMS 12 345.6 Total 161,267.2

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The I-70 segment included in the coverage of Node Building #1 will require a bandwidth of 30,144 kbps (30.1 Mbps). The bandwidth requirement will likely increase as the traffic volume continues to rise along the corridor. The bandwidth required by individual

devices is shown in Table 7.

Table 7

(Devices Communicating Directly to Node Building #1)

Region 6 Maintenance Facility

The CDOT Region 6 building will receive the majority of the information transmitted from devices along the southern section of the network, as shown in Figure 3.

Figure 3

Region 6 Communication Building Coverage

The CDOT Region 6 Maintenance Facility will have a dual purpose. The primary

purpose is to provide remote maintenance and operations of the HOV corridor, including incident monitoring for maintenance purposes and verification of the DMS messages and gate status. The secondary purpose is to act as a pass-through for all of the data gathered south of 6th Avenue, along I-25, I-225, and C-470, until a full region-wide fiber deployment is completed. The Tier 3 data and video system along these corridors will be placed on the Tier 1 (statewide) system at 2000 South Holly. Data and video

Devices Number of Devices Bandwidth (kbps) ATR 1 28.8 CCTV 3 30,000.0 DMS 4 115.2 Total 30,144.0

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processing and redistribution of this information will be the responsibility of the CDOT TOC.

The bandwidth for each segment is 61,568 kbps (61.6 Mbps), 172.8 kbps (0.2 Mbps), and 10,460.8 kbps (10.5 Mbps) respectively. The individual devices are shown in Tables 8, 9,10, and 11.

Table 8

Bandwidth Requirements along I-25 (6th Ave. to Colorado Blvd.)

There is currently no fiber optic cable running between 6th Avenue and Colorado Boulevard. The existing devices between 6th Ave. and Colorado Blvd. are wireless and telephone connected. These devices can continue to operate with the current

connections; however, fiber optic cable will need to be placed along I-25 if future devices are to be connected by fiber optic lines.

Table 9

Bandwidth Requirements along I-25 (Colorado Blvd. to Lincoln Ave.)

As Douglas County continues to grow, the need for additional devices may become apparent and the bandwidth requirements will increase as ITS elements continue to be deployed south of Lincoln Ave.

As the ITS development continues in the Denver Metro Area, ramp meters will be installed along the southbound ramps to I-25. As the ramp meters are installed, the Automatic Traffic Recorders will be removed. For the purposes of this analysis, the bandwidth for the ATR’s is included, as the bandwidth for the future ramp meters will be an equivalent replacement. Devices Number of Devices Bandwidth (kbps) ATR 8 230.4 HAR BROADCAST 1 64.0 DMS 1 28.8 Total 323.2 Devices Number of Devices Bandwidth (kbps) ATR 16 460.8 CCTV 6 60000.0 RAMP METER 12 345.6 DMS 4 115.2 HAR SIGN 1 28.8 HAR STATION 1 64.0 Total 61,014.4

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Table 10

Bandwidth Requirements along C-470 (Wadsworth Blvd. To I-25)

The need for additional devices may become apparent as the Highlands Ranch area continues to grow. As development continues along the entire C-470 corridor, the need for additional ITS will need to be addressed. Additional devices and fiber optic cable will eventually be needed along C-470 to the I-70 interchange. Completion of the C-470 ITS network to I-70 may reroute the communication from going directly to the Region 6 building to going through the TOC building along 6th Ave.

Table 11

Traffic Operations Center

The TOC will directly receive the information from the devices along 6th Avenue as shown in Figure 4. It will also serve as a concentration point for data and video from the other three CDOT facilities.

Devices Number of Devices Bandwidth (kbps) ATR 2 57.6 RAMP METER 4 115.2 DMS 1 28.8 Total 201.6 Devices Number of Devices Bandwidth (kbps) CCTV 2 20,000.0 RAMP METER 13 374.4 DMS 2 57.6 HAR SIGN 1 28.8 Total 20,460.8

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Figure 4

Traffic Operations Center Coverage

The bandwidth needed to collect the data from devices on 6th Avenue is 40,288 kbps (40.3 Mbps). Individual devices along 6th Avenue and their respective bandwidths are shown in Table 12.

Table 12

Bandwidth Requirements along 6th Avenue

As build-out of the fiber optic network continues, deploying a set of rings throughout the Denver metropolitan area, the ability for full redundancy throughout the network will be provided. Additionally, the configuration of the Tier 1 network (SONET/TDM) will permit the operation center to be located anywhere along any of the trunk line routes and still provide the same level of operations and control as the current location.

Devices Number of Devices Bandwidth (kbps) ATR 8 230.4 CCTV 4 40,000.0 RAMP METER 1 28.8 DMS 1 28.8 Total 40,288.0

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Conclusions and Recommendations

The four CDOT facilities, as previously mentioned, will provide the Denver area with an ITS network which will be able collect and distribute traffic information. Table 13 provides a summary of the bandwidth requirements of each corridor evaluated in this study.

Table 13

Bandwidth Requirements Summary

CDOT is in the process of identifying a new, permanent location for the traffic operations center. As stated previously, with the network technology being used, the location of the building is only limited by access to the trunk fiber ring. Locating the TOC off of the main trunk fiber ring may require a connection between the TOC and the trunk line.

Segment Segment Description

Bandwidth Required

(Mbps)

I-25 120th St. to 6th Ave. 191.3

I-25 6th Ave. to Colorado Blvd. 0.3

I-25 Colorado Blvd. To Lincoln Ave. 61.0

6th Ave Kipling St. to I-25 40.3

U.S. 36 Sheridan Blvd. To I-25 40.3

C-470 Wadsworth Blvd. To I-25 0.2

I-225 I-225 To I-70 20.5

I-70 Pecos St. to York St. 30.1