PG&E appears to have issued a new design directive in March 2021 for conduits between a PG&E transformer and a service enclosure for a traffic signal or other highway electrical device.  Thanks to staff from Alameda County for passing along this information to W-Trans.  The directive evidently requires there be no pull boxes in the service run.  
If anyone has a link to this directive, please forward it to me.  
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Designing traffic signals at locations along old streets can be a special challenge for traffic signal designers.  In a recent project on San Carlos Avenue, in an area that the utility maps showed no conflicts, the contractor hit multiple conflicts.  A
About a foot below the surface looked like the top of an old retaining wall.  The contractor was curious and kept digging, and about two feet below that hit what looked like the top of another old retaining wall.  (The boot visible in the pictur...
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As a frequent bicyclists, one of my regular frustrations is the inadequate bicycle detection.  The industry guidelines suggest a single 6-foot long detection zone at the stop bar in a bike lane or in vehicle lanes is adequate.  However, when I am on my bike, approaching an intersection with one or two vehicles waiting, and see the light go green, I often groan because I can see the green light will not last long enough for me to make it.  I am left with the choice of pumping really hard to tr...
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A couple decades ago detector loops (wires in pavement) were sealed into their sawed slots with epoxy.  About 10 or so years ago the industry changed to asphaltic emulsion sealant.  Why the change?   It turns out that pavement wears down with time but epoxy does not.  So as pavement ages, epoxy would stick up.  As pavement ages more, the epoxy would break loose, and the wires would pop up out of the sawed slot and eventually break from the tire strikes.  The photo shows sawed slots, empty saw...
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Seems like there are more underground utility conflicts than a decade ago, and they are getting harder to deal with.  One signal mast arm pole foundation within a new traffic signal was not cooperating with standard installation techniques.  We had to work around two adjacent utility trenches that had been backfilled with sand.  There was one trench on each side of the new foundation (with adequate clearance) and the sand was caving into the drilled foundation hole and exposing the utility pi...
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Thanks to action of an RRFB vendor, the Rapid Rectangular Flashing Beacon is back.  According to Aaron Lockwood of Carmanah Technologies Corp, Carmanah recently bought out the company that held the patent on part of the RRFB features and released the patents.  FHWA has reinstated the Interim Approval status at the federal level.  Mr. Lockwood is under the impression California has already obtained the blanket approval status that it held before for these devices.   I am hoping to obtain confi...
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Rectangular rapid flashing beacons (RRFBs) have gained a lot of popularity in the last few years since the FHWA and Caltrans granted what is called Interim Approval of the device.  Unfortulately, FHWA recently withdrew approval, and within the last month Caltrans followed suit.  It seems one vendor of the product obtained a patent for the central part of the technology, and FHWA does not endorse products that are patented.   

W-Trans has been following posts on the ITE discussion board and has...
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A number of public agencies have decided to allow local artists to paint controller cabinets.  City of San Jose, for example, allows schools or neighborhood groups to paint the cabinets with art depicting local themes.   City of Oakland downtown business alliance pays local artists to paint the cabinets.  This is an example from the Telegraph/17th intersection in Oakland.  With permission from the artist, Elisa Carozza, the attached photo shows the first two completed sides of the artwork.  E...
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Sonoma County has launched a new use of the pedestrian hybrid beacon at SMART Rail crossings in the Penngrove and Fulton communities.   Both crossings have signalized intersections over 700 feet away, too far for use of traditional rail preempt.  A study by W-Trans concluded a queue cutter signal was the best option to keep the crossing safe once SMART revenue service began.   However, the need to the queue cutter only occurred in the evening peak hour.   Since signals that remain green for e...
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Several projects in the SF Bay Area that are scheduled for construction in 2017 have had bid openings in the last month or two.  A pattern of higher bid prices for electrical work has emerged, and a smaller number of bids are being submitted (one of two instead of the usual four or five).  W-Trans staff have spoken with estimators from four electrical contractors.  Our summary is that contractors have an abundance of work to bid on and do not have any need to "sharpen their pencils" this year...
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Battery backup systems (BBS) are equivalent to a UPS that keeps traffic signals running for two or more hours after a power failure.   The photo shows a Type 332 controller cabinet (typical installation on a Caltrans highway) and the somewhat smaller cabinet on the right is the BBS.  BBS started seeing interest in California about 2001 when the state had an unusually high number of brownouts.   BBS started getting deployed in greater numbers in about 2004 after a CPUC study documented their b...
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There are three observations I’d like to share with the folks in the professional community who are involved in traffic signal coordination, and I’m hoping to hear if others have noticed anything similar.  

First, when implementing coordination plans that have been developed with an optimization model, I often find ways to improve operations during the fine tuning step.  The last step of the process is to input the final timing settings back into the model and run it one last time to ge...

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The City of Redding is testing a new type of pedestrian signal head with a yellow outline in an attempt to reduce pedestrian conflicts with right turning vehicles.   See http://www.citylab.com/cityfixer/2015/12/will-this-new-type-of-crossing-signal-keep-pedestrians-safe/420279/?utm_source=SFTwitter for more information.    Please send a response post if you have direct experience with the trial or trials of other devices with a similar goal.   
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Question:  How do I tell if a traffic signal controller is equipped with a GPS or satellite clock?
Answer:  The first clue is shown in the photo below.  There should be an antenna on the top of the cabinet, often referred to as a puck because of its shape.  

Inside the cabinet the unit is typically mounted in the back, near the top of the rack, as shown in the photo.  In this case it is a McCain clock unit.  

The black cable connects to the antennae.  The grey cable connects to the controller un...
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Terminal compartments are part of a traffic signal installation that allows circuits to be connected without using splices in pull boxes.  The picture below shows what is inside.  There are two pictures of the same terminal strip, taken from either side.  In the first picture you will see the posts numbered from 1-12.  The posts go all the way through.  In the second picture you can see single wires attached to 6 of the posts.  You can attach up to 3 wires per side, or 6 wires total. 

 

So...

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Mid-sized and smaller cities have frequently chosen to provide protected left turn phasing on main street approaches of signalized intersections, citing a belief that it provided safer operations.  Recently however, this traditional belief has been challenged for a variety of reasons.  An option that combines protected phasing with permitted phasing emerged and is starting to see deployment.  Also, federal research identified a new approach in the signal display, using a flashing yellow arrow...
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Caltrans and Siemens are now near the one-year anniversary of our contract to install ramp meter signals along Route 101 in San Mateo County.  It is part of a new ventures program authorized by the California legislature to use design-build contracting for infrastructure.  Information on the overall program can be found at http://www.dot.ca.gov/hq/oppd/designbuild/db.htm.  Specific information on the San Mateo project is at http://www.dot.ca.gov/hq/oppd/designbuild/sanmateo.htm

Siemens has ado...
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Question:  How are detector loops installed?
Answer:  There is a variety of equipment.  The photo below shows a round loop saw (Caltrans Type E).  The second photo shows a saw that cuts straight lines.  This saw can be used in combination with the previous to cut the lead in slots or can be used by itself to make a square loop (Caltrans Type A or D).  It takes about 5 minutes to cut a Type E loop, 10 minutes to cut a Type A loop, and 15 minutes to cut a Type E loop.  The cutters have a jet of ...
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ITE and IMSA have teamed up and produced a new "Traffic Signal Maintenance Handbook". It is available at http://www.ite.org/emodules/scriptcontent/Orders/ProductDetail.cfm?pc=TB-021. Republic ITS staff gave a presentation at the recent ITE Western District meeting with a summary of the new Handbook and recommendations for maintenance of new technology components. These include:

• LED Signal Heads
  • Re-lamp every 5-10 years
• Video Detection Systems (VIDS)
  • Annually test aiming and accuracy o...

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Question:  I have a question I was hoping you could help me with.  Regarding type 1B pole foundations (straight pole, 4.5” OD)  We noticed that California recently updated their requirements on 1B pole foundations, making them much deeper and complicated. The requirement used to be 3’ deep with J-bolts, now it’s 5’ deep with an anchor plate.  I was wondering if you knew anything about this or could refer me to an “expert” in this area.  See the attached new requirement.  Thank you...
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The Manual on Uniform Traffic Control Devices is a nationwide guideline perscribing how traffic control devices get built.  California adopts the MUTCD after it gets updated, and incorporates State-specific details in the process.  To see the latest MUTCD and how CA is planning to adopt it, see http://www.dot.ca.gov/hq/traffops/signtech/mutcdsupp/ca_mutcd2011_draftrevisions.htm
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Those big traffic signal mast arm poles are pretty beefy and sturdy.  The biggest is the Type 29. Sometimes it seems like one of those would never come down.  Thanks to Republic ITS coworker Joseph Rhys in the Sacramento area, who responded to a knockdown call and had time and presence of mind to snap a picture.  


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Question:  There are three new traffic signals being built in my City.  The City Engineer has suggested checking the traffic signal foundation locations before the foundations are excavated and formed.  What needs to be done?
Answer:  There are four items to check.  1) Look for potential conflicts with underground utilities.  Relocate the foundation away from the conflict if there are any.  2) Check that the signal heads that will be mounted on each pole can be seen clearly by drivers.  Obstru...
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Question:  What are the best procedures for installing and maintaining Battery Backup Systems? 

 

:Answer:   Republic ITS recommends installing BBS only at critical or important locations, and at least annual testing and replacement of batteries on a 3-5 year schedule.  A quick review of ITE and IMSA websites did not show any relevant publications.  Surveying a few SF Bay Area agencies revealed the following:

•  Battery life seems to be about 5 years.  Costs to repair batteries is about $1...

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The new CA MUTCD (California Manual on Uniform Traffic Control Devices) has been released.  There are two important updates relative to traffic signal operations.  First is the bicycle timing requirements, which have been adopted as presented in draft form.  (See post dated Dec 3, 2009).  The second is pedestrian Walk and Flashing Don’t Walk times.  The new standard is not substantially changed from before, but a recommended walking speed of 2.8 feet per second has been added when slow movi...

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Question:  My City has been responding to calls lately about bikes not getting detected at traffic signals.  We use the Type D loop at the front of all our Stop Bar detection, which is supposed to pick up bicycles.  Do we need to connect that front loop to its own Detector Cable? 

Answer:  The typical detector loop has a Type D loop right at the stop bar (the bike loop), and three Type A loops connected in series-parallel extending away from the intersection.  As you noted, this style of de...

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Question:  How does an IISNS mounting work? 

Answer:  Internally Illuminated Street Name Signs are typically mounted under a traffic signal mast arm.  Older style signs are typically light be fluorescent tubes and new style signs are LED.  The mountings connect the sign housing to the mast arm, and are hinged so the sign can swing in the wind and reduce what would otherwise be a large wind load.  The photo shows a close up of an IISNS from Alameda County.

There is a base that connects...

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Question:  Some traffic signals in snow country with LED lamps are getting clogged with snow.  Are there any new products to address this problem? 

Answer:  The lower wattage of LED traffic signal heads compared to incandescent also means the lamps generate less heat.  This allows snow or ice to form on the head and sometimes block the display.  In at least one case in Wisconsin, it has become a legal issue.  See http://www.todaystmj4.com/news/local/79008352.html

McCain Traffic Supply has d...

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Question:  I’ve been told Caltrans recently issued new guidelines on accommodating bicycles at signalized intersections.  Where can I find the details?

Answer:  In August, 2009, Caltrans issued a Policy Directive about new requirements for bicycle detection at signalized intersections and new guidelines for traffic signal timing to accommodate bicycle travel speeds.  You can find the full document at http://www.dot.ca.gov/hq/traffops/signtech/signdel/policy/09-06.pdf.  The document describ...

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Question:  My City has a traffic signal with a protected left turn that is to be converted to a permissive.  There is a mast arm for this move which currently has a signal heads for the left turn phase and through phase.  I have been told there is a product available from Pelco called the Astro-Brac that I can use to replace both the existing heads with one doghouse head, and mount it in between the current head locations.  What more can you tell me? 

Answer:  Pelco has a product called AB-0...

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Question:  I have two new signal systems about 500’ apart and speed limit is 30mph.  I worried about there would be visibility conflict between these two signals.  So, in what situation the louvered signal head is required?

 Answer:  The issue with closely spaced intersections is that the driver wating at the stop bar of the first one might see a green at the second one and start driving, even when the closer signal display is still red.  The Caltrans traffic manual had a guideline to rest...

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Question:  My City has recently installed a new traffic signal.  There is a curve in the southbound approach that limits the visibility of the signal heads.  How do I know if I need a Supplemental head or not?    

 

Answer:  Chapter 4 of the California MUTCD has your guidance.  First determine your travel speed on the approach.  Then look up the minimum visibility requirement in Table 4D-1 of the CA MUTCD http://www.dot.ca.gov/hq/traffops/signtech/mutcdsupp/pdf/camutcd/CAMUTCD-Part4.pdf  . ...

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Question:  Caltrans publishes traffic count data that is organized by Route number and post mile.  The database sometimes includes counts on either side of a cross street, labeled as “Back” and “Ahead”.  The Ahead data for one posting should match the Back data for the next one, but sometimes they don’t.  What number should be used when they don’t match? 

 

Answer:  Caltrans traffic data is available on their website at http://www.dot.ca.gov/hq/traffops/saferesr/trafdata/2000al...

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Question:  For left turn signal heads, we usually install it on the mast arm and the far side 1-b pole.  The MUTCD requires a 40 degree viewing angle from the left turn lane.  There are situations that the far side left turn signal head is outside the 40 degree angle zone due to the width of the street.  I know Caltrans doesn’t like to put the 1-b on the median too.  We required to have at least two signal heads for each moment.  So, what’s your opinion for the second left turn signal hea...

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Question:  In a recent signal design, I needed the mast arm signal raised a bit higher for clearance and suggested connecting the MAS mount between the yellow and green indications.  A reviewer told me this is not a good idea, and I’m hoping for a more detailed reason why not. 

Answer:  Caltrans Standard Plan ES-4D (http://www.dot.ca.gov/hq/esc/oe/project_plans/highway_plans/stdplans_US-customary-units_06/viewable_pdf/rspes-04d.pdf) shows the MAS mounting but doesn’t really explain how th...

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Question:  I’m designing a traffic signal at an intersection with a heavy right turn out of a minor street, plus a very low volume pedestrian crossing that is in conflict with the right turn move.  I’m thinking of having a right turn arrow that will display a red when there are pedestrians, and will show a green when there are no pedestrians.  The controller is a 170 with McCain software.  Here’s a sketch of what I’m wanting to do, how do I make it work? 

 

Answer:  McCain software h...

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Question:  When gap extension is programmed, do cities generally use the detectors to have this signal timing setting, or do cities program the controllers to have this setting?

Answer:  I’m used to thinking in terms of Gap Reduction.  Gap Reduction is done entirely in the controller unit inputs.

Extension is a term that is usually applied to a detector input.  Extension can be done either in the Detector Sensor (the part that sits in the rack/shelf in the controller cabinet), if it is the ...

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