Tag Archives: VMS

Automated Queue Warning Detection System in the Work Zone

Prepare to Stop VMSThis summer, Region Two began work on Redwood Road from I-80 to North Temple to rotomill and resurface the roadway with a thin bonded PCCP 6” overlay. One of the biggest challenges on the job was maintaining traffic through the work zone while also maintaining side-street and business access. This issue was complicated by the high number of large trucks in the area. These trucks not only utilize a significant amount of available queue space on the ramps, they also take more time to climb the incline at the interchange before clearing the signal. These factors required significant coordination to keep traffic moving.

Our contractor, Dry Creek Structures, and construction crew worked closely with the Traffic Signal Maintenance group to split phase signals and move detection zones to accommodate traffic through the work zone. We also worked closely with Grant Farnsworth at the TOC Traffic Signals Desk to adjust signal timing as the work zone configuration changed.

From a traffic safety perspective, our top priority was to minimize queuing on the
westbound I-80 ramp and prevent stopped traffic on mainline I-80. Despite the team’s best efforts, traffic was occasionally still backing onto mainline I-80 while waiting to exit at Redwood Road. To help address this queuing problem, working with Marge Rasmussen in Region Two Traffic and Safety, and Project Manager Peter
Tang, an Automated Queue Warning Detection System was change ordered into
the project and installed on the I-80 westbound off-ramp to Redwood Road.
With this system, the occupancy rate was monitored near the gore point of the off-ramp. When the system detected stopped cars at this location, a warning message was activated at a Variable Message Sign (VMS) upstream of the off-ramp alerting motorists of “STOPPED TRAFFIC AHEAD” and “PREPARE TO STOP.”

How it works: A sub-contracted vendor (Ver-Mac) installed a radar sensor, cellular
modem and solar panel on a highway lighting pole near the bottom of the off
ramp. They also placed a VMS equipped with a cellular modem upstream of the off
ramp. When the vendor’s software system (Jam-Logic) detected an occupancy rate greater than 10 percent at this location, a message was activated at the VMS alerting travelers to the stopped condition ahead. Once the queued traffic had dissipated, the VMS message was automatically turned off and remained off until ramp queuing was detected again.

In addition to the VMS message activating when a queue was detected, email messages were also sent to the TOC Operators, the Signal Timing Engineer and the Resident Engineer, alerting them to the situation. When possible, adjustments were made to the signal timing to help clear the ramp traffic.

Results: The project team is not aware of any accidents at this location after the automated queue warning system was installed. Typically, the system was activated 10 times each day throughout the week or an average of 13.4 times on weekdays. Even during low traffic volumes, just a few long trucks on the ramp can back up traffic and activate the system. While the system was live, the queue warning messages were displayed 256 times for a total of 2,327 minutes. The average display time was 9 minutes. The maximum display time was 56 minutes (on August 23 starting at 9:19 a.m.).

Logical Automation Rules Chart“Doing advanced queue warning is a great operational benefit, but what the TOC appreciated most was the communication between the project and the control room. When the control room knows what’s going on, we’ll help out in any way that we can. In this case, we monitored the queue system and helped ensure that it was functioning as advertised – which it was,” explained Glenn Blackwelder, Traffic Operations Engineer.

Future Applications: The automated queue warning detection system was a valuable addition to our “tool box” for managing traffic issues in the construction work zone on the Redwood Road project. In the future, perhaps other projects could benefit from this or other types of technology to help address traffic control issues within construction work zones.

This guest post was written by Bryan Chamberlain, Region Two Resident Engineer, and was originally published in the Region Two Fall 2014 Newsletter.

TWEETING ABOUT TRAFFIC

How UDOT Uses Social Media, a guest post by Andrew Johnson, former UDOT employee.

Chances are you’ve been caught in a traffic jam, wishing you knew about it ahead of time. The Utah Department of Transportation is consistently making strides to keep Utah drivers informed before they get behind the wheel, and a large part of UDOT’s efforts is through the use of social media. (NEVER Tweet and drive!)

UDOT’s innovative approach to keeping commuters up to speed includes regular updates through their Twitter feed. This gives drivers access to real-time information about road closures, accidents, construction projects and abnormal delays, and also provides the public with direct access to UDOT employees.

Here’s an example of a recent conversation on Twitter:

Tweets keep motorists informed — CLICK TO ENLARGE.

In this example, someone Tweeted UDOT with information about a possible malfunctioning traffic signal. UDOT responded to the Tweet, and included the signal technicians at the Traffic Operations Center to relay that information. At that point, the technicians dialed into the signal, and were able to diagnose a potential problem. Since Twitter is a public forum, and anyone who is following @UtahDOT can see the conversation, other people may join the dialog and contribute information. I noticed the Tweets, and was able to contribute my two cents.

UDOT Traffic is another fantastic resource available with the click of a mouse or the swipe of your smart phone. UDOT Traffic includes a network of closed-circuit television cameras, electronic variable message signs, coordinated traffic signals, traffic sensors, ramp meters and weather stations. Together, this network delivers real-time information directly to employees at the Traffic Operations Center and to the UDOT Traffic website. Employees can take the information received at the TOC, relay that information on Twitter and Facebook, and thousands of people instantly receive that information and can plan their routes accordingly.

Travel times help road users to decide to continue as planned or to take an alternate route.

As you travel along Utah’s freeways, you may notice large black signs spanning across the lanes overhead. These are called Variable Message Signs, or VMS, and are extremely effective in communicating important information to public. Located at key points across the state, these signs are controlled by operators at the UDOT Traffic Operations Center, and can be activated with custom messages as needed. The messages on these signs are governed by UDOT policies, and format, length and wording is dictated by the Manual on Uniform Traffic Control Devices (MUTCD) by the Federal Highway Administration.

These signs provide drivers with clear, concise messages about freeway conditions, and drivers can then decide if they want to continue on the same route or choose an alternate route. VMS boards can also be coordinated with other State agencies like the Department of Public Safety to run messages about safety belt laws, and other public safety campaigns. You may also see messages about air quality alerts through the Utah Department of Environmental Quality.

Despite the integration of social media into their arsenal, not all of UDOT’s efforts into reducing delays for drivers are strictly reactionary. In fact, a large number of construction projects around the State are a response to future demands, and UDOT wants to make sure Utah’s transportation network is efficient for years to come.

Information and pictures provided by 24saltlake.com.