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Bridge Traffic Steadily Flows With Portable Traffic Devices

A potentially huge traffic nightmare is defused when technology saves the day.

Wed September 11, 2013 - National Edition
Construction Equipment Guide

Coordinating single-lane road traffic with the ups and downs of the Allanburg lift bridge required North America Traffic to fast-track new custom controls for its portable traffic signals.
Coordinating single-lane road traffic with the ups and downs of the Allanburg lift bridge required North America Traffic to fast-track new custom controls for its portable traffic signals.

When Jonathan Abraham saw the request for portable traffic signals at the Allanburg Bridge, he saw it as just a routine order for a road repair project. Bridge repairs are bread and butter work for North America Traffic Inc. (NAT), where Abraham is the firm’s service and compliance coordinator.

But as spring approached and the project ran into a delay, the signaling challenges became anything but routine. Then, Abraham and NAT were called upon to show how their custom design capabilities set the firm apart from other portable signal manufacturers.

Located in the Niagara region of southern Ontario, the Allanburg lift bridge spans 200 ft. (61 m) across the Welland Canal, part of the St. Lawrence Seaway system. Maintenance to the road was planned while seasonal Seaway traffic was closed over the winter months. NAT, based in nearby Port Colborne, ON, was contracted to provide a traffic control solution to limit road traffic to a single lane. The order called for two sets of portable traffic signals to work in conjunction with the bridge’s existing traffic control system: one at each end of the bridge plus two for the intersection on its east end.

A New Season Calls

for New Signaling

When the construction work ran into delays and extended into the opening of the 2013 shipping season, the traffic control situation suddenly became much more complex. The lift bridge must be raised to allow ships to pass on the canal. Road traffic crossing the canal is normally controlled by traffic lights operated from the Seaway Authority’s remote station, a few miles from the bridge.

To manage traffic for both construction work on the bridge and Seaway traffic under it, NAT’s portable signals were now required to replicate the Seaway’s remote-operated controls. Normally, the signals are coordinated so when the bridge is about to be raised, the traffic signals allow vehicles to clear the bridge without getting caught between the lights. The portable signals would have to integrate with the bridge controls, and also coordinate the single-lane flow of road traffic.

Seven-Day Turnaround

The contractor foresaw the delay in the project and notified NAT of the difficulty two weeks before the Seaway would open.

“Our technician went out to the site on a Wednesday to scope out the traffic and signaling. We coordinated with the Seaway technicians and the MTO [Ontario Ministry of Transportation], and programmed a new control module. We had the portable signals operating by the following Thursday, on the first day of spring,” Abraham said.

NAT developed the required controls to synchronize the portable traffic signals with the bridge control signals, including an override requested by MTO and a confirmation signal back to the Seaway control station. Because of NAT’s rapid turnaround on the new control system, the contractor was able to proceed with the bridge repairs with no further hold-ups.

Designed for Customization

According to Abraham, the flexibility to meet the needs of the Allanburg Bridge project is inherent in the design of NAT portable traffic signals.

“Our programming circuitry has a built-in pre-empting option that we often use to manage traffic at railway crossings. The signals cycle in normal pattern for one-lane traffic, until the sequence is pre-empted by a relay from the railway’s crossing system. We adapted the railway pre-emption feature into a ’hold for bridge’ program, including a 2-minute delay for traffic to clear the lane before the bridge lift was activated.

“After we delivered the portable signals to the site, we simply connected a cable to the bridge control circuitry through a 12VDC to 120VAC relay.”

The bridge repairs required two months more to complete, as work was interrupted repeatedly for canal traffic, but the portable signals operated flawlessly throughout the project. Powered by highly efficient solar cells and battery packs, NAT signals have a 30 day autonomy rating for periods of low light or minimal sun exposure. The signals are synchronized by radio transmissions, but had no difficulty with potential interference from boat communications and the steel structure of the bridge.

Customer-Driven Solutions

The railway pre-emption, or hold-for-bridge feature, is just one of many program modules provided on NAT portable signals. NAT also has provided custom control systems that respond to a wide range of sensors for detecting motion, proximity and radiation, among others. All systems are equipped with manual and remote control overrides.

“This is one case where our experience working on site with customers really paid off,” said Abraham. “Every new solution we develop becomes part of the tool kit for our future control systems. As we deal with this every day, we have the knowledge of the technology available to adapt the programming and integrate it with the existing signal system.

“This project turned around just a little quicker because our plant is so close to this bridge. But, other than the extra day or so for travel time, we would do the same for any customer.”

About North America Traffic Inc.

North America Traffic was launched as R.C. Flagman in 1993 when Peter Vieveen built the world’s first Remote Controlled Flagman out of his garage. At the time, Vieveen was a senior estimator in the construction industry with more than 25 years of construction experience. He understood the importance of reducing costs while increasing safety. North America Traffic now operates a full production facility, and its products have been used on more than 3,000 projects across North America. Today, the company has eight different models of portable traffic signals, flashing beacons and flagging systems to meet all traffic control needs.

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