Dallas Horseshoe ATM Design

Mike Holt, PE, PTOE Senior ITS/Traffic

Engineering Manager

Project Background

$798 million Design-Build project south of

Downtown Dallas

Reconstruction of I-30/I-35E interchange and

approaches across Trinity River

Construction of new signature bridge over I-30

Started construction summer 2013; scheduled

completion fall 2017

Project Team

Texas DOT is owner

Pegasus Link Constructors is D-B Joint Venture (Fluor Enterprises and Balfour Beatty Infrastructure)

Parsons Brinckerhoff is lead design firm

Existing Conditions

460,000 ADT through interchange

I-30/35E “canyon” depressed freeway section

with 8 mainline lanes and auxiliary lanes

Extensive existing signage

Multiple lane closures and ramp detours

Existing Aerial Overview

Existing Conditions Photos

ATM Overview ATM proposed for value added project feature

ATM Overview

Initial proposal included:

Overhead lane control signals (LCS)

Dynamic message signs

Travel time signs

Contractor negotiated DMS and TTS out of

project scope

PB proceeded with LCS design

Lane Control Signals

8 locations include:

New overhead gantries (4)

Existing bridge attachments (3)

Existing overhead sign bridge attachment (1)

Lane Control Signals

Skyline SlimLine LED Variable Message Signs

5’ x 5’ full color matrix

64 x 064 pixel layout

336S cabinet

2070 ATC controller

Envoy DMS Central Control Software

Design Challenges

Power

Communications

Structural attachments

Sign visibility

Power

120/240 VAC

50 amp service to cabinet

20 amp service to each LCS

Alpha Micro Secure 100 UPS

Power Challenges

Need meter and disconnect for some cabinets

Use existing ITS service for some cabinets

Service points were not always close to LCS

Prepared voltage drop calculations for service

conductor sizing

Communications Wireless communications to temp. project TMC

Sierra Wireless AirLink LS300 Gateway

AntennaPlus Hockey Puck antenna

Cat 5e cabling from cabinet to LCS

Communications Challenges

Existing fiber network not accessible

Cellular comm. to temporary TMC

Cat 5e cabling limitations (<300’)

Communications Schematic

Structural Attachments

Gantry

Existing bridge

Existing OH sign bridge

Submitted customized structural details

Structural Details

Structural Details

Structural Details

Sign Visibility Reviewed available guidance documents for LCS

visibility requirements:

MUTCD Section 2L.03

Legibility and Visibility of Changeable Message Signs

Offers guidance that CMS on roadways with speed limits of 55

mph or higher that messages should be legible from a

minimum distance of 600 feet for nighttime conditions and 800

feet for normal daylight conditions.

Sign Visibility MUTCD Section 4D.12

Visibility, Aiming and Shielding of Signal Faces Offers guidance that traffic signal faces should be continuously

visible to approaching traffic, from a point at least the minimum sight distance provided in Table 4D-2

85th-Percentile Speed Minimum Sight Distance

20 mph 175 feet

25 mph 215 feet

30 mph 270 feet

35 mph 325 feet

40 mph 390 feet

45 mph 460 feet

50 mph 540 feet

55 mph 625 feet

Sign Visibility

MUTCD Section 4M.03

Design of Lane-Use Control Signals

States the color of lane-use control signal installations shall be

clearly visible for 2,300 feet at all times, unless otherwise

physically obstructed

Sign Visibility Analysis

Section 2L.03 applies to CMS (messages vs. LCS)

Section 4D.12 addresses traffic signals (single color)

Section 4M.03 most commonly applied to reversible-

lane control and toll plaza lanes (more complex)

Section 4D.12 (625’) appears most appropriate for LCS

visibility

LCS Deployment Recommendations

LCS #1 (I-30 EB) – proposed gantry

LCS #2 (I-30 EB) – proposed gantry

LCS #3 (I-30 WB) – existing bridge

LCS #4 (I-30 WB) – existing bridge

LCS #5 (I-35E NB) – proposed gantry

LCS #6 (I-35E NB) – existing bridge

LCS #7 (I-35E SB) – existing OH sign structure

LCS #8 (I-35E SB) – proposed gantry

Gantry Plan

Bridge Mount Plan

OSB Mount Plan

LCS Deployment

LCS Deployment

LCS Deployment

LCS Deployment

LCS Mounting

Current Progress

Current Progress