General Infrastructure

[sm89]

Actually according to the Mass Vehicle code you can take a right on red even with an arrow as long as there isn't a no turn on red sign.

Also on a one way road intersecting another one way road you can take a left on red. I wish more drivers would figure that one out.

It will be no turn on red. Almost every intersection is Cambridge is no turn on red.

The lane arrangement is 2 through, 1 right, 1 bike through, so turning on red will not be allowed as it would cut off bikes.

 

[odurandina]

How do they assume that? Do they give out licenses to people who can't drive?

I'm looking at what's coming before i move into the path of a possible bike.

btw, some of these crazies on bikes would do themselves a solid by not blasting through intersections.

All those 'no turn on red's' accomplish is jam up traffic.

 

[tysmith95]

How do they assume that? Do they give out licenses to people who can't drive?

I'm looking at what's coming before i move into the path of a possible bike.

btw, some of these crazies on bikes would do themselves a solid by not blasting through intersections.

All those 'no turn on red's' accomplish is jam up traffic.

The right hook is probably the most deadly collision that bike riders regularly face (besides dooring). Most drivers aren't used to having to check their side mirrors for bikes.

 

[chmeeee]

All those 'no turn on red's' accomplish is jam up traffic.

Apparently pedestrian safety is not a thing.

 

[fattony]

All those 'no turn on red's' accomplish is jam up traffic.

Aside from pedestrian protection, which I don't think requires any additional explanation, "no turn on red" is actually a very effective protection against gridlock. I mean literal gridlock - when cars wedge themselves into intersections that they cannot clear, get trapped, and thus obstruct cars from moving on the next light phase.

 

[JeffDowntown]

Aside from pedestrian protection, which I don't think requires any additional explanation, "no turn on red" is actually a very effective protection against gridlock. I mean literal gridlock - when cars wedge themselves into intersections that they cannot clear, get trapped, and thus obstruct cars from moving on the next light phase.

Also, there are intersections where the sight lines simply do not support safe right turn on red (but drivers will be dumb if you let them).

Great example is Herald Street where it ends at Albany Street. Herald Street drivers (aggressively trying to get to I-93) would love to turn right on red, but it is not allowed. Albany Street moves pretty quickly out of downtown, and the right hand lane is a pop up exit out of the O'Neill Tunnel. Sight lines from Herald can not see this traffic until it is too late.

 

[Roxxma]

No turn on red is a vestige of the energy crises in the 1970s, meant to prevent excessive idling. In urban areas it should be the default. Per a FHWA study on practices in other countries, Germany, where safety is taken into account over ease of moving vehicle traffic when designing intersections, right on red is only permitted "if the following criteria are met: Motorized traffic has clear lines of sight to all bicycle or pedestrian crossings. Signals are present to control pedestrian crossings. Conflicting pedestrians do not cross more than two lanes. No bicycle traffic is present. No more than two serious accidents have occurred at the intersection in the past three years."

 

[Charlie_mta]

I agree. You're lucky if the driver even makes a full stop on "right turn on red." Many times they just blow right on through.

 

[Joel N. Weber II]

Re: Porter Sq

It might also be possible to reconfigure the plaza to provide a separated right turn lane from Somerville Ave to Mass Ave on a more direct path sort of like how the Wilson Sq right turn from Somerville Ave to Elm St works (but probably without copying Wilson Sq's parking). It might also make sense to move the 83 bus stop into that area.

If this ends up being done, it might make sense to reconfigure the existing mall entrance and right turn exit to be an entrance only, and then use part of the existing left turn exit to feed right turning traffic into that new Somerville Ave to Mass Ave northbound path, and have the traffic from Somerville Ave merge onto Mass Ave a bit to the southeast of that mall entrance, with the traffic from Somerville Ave having a stop sign at Mass Ave. (Mall traffic heading to Mass Ave northbound would probably then encounter two stop signs, the first when merging with the traffic from Somerville Ave and the second when merging with traffic from Mass Ave.)

 

[jass]

I didnt realize this was a thing, but glad to see it.

Two intersections in Lexington with Mass Ave are being converted from some stupid circle thing to signalized intersections.

Mass Ave and Pleasant Street
https://goo.gl/maps/3s8Y857Pq6n

Mass Ave and Maple Street
https://goo.gl/maps/S9ZCC1EKbkJ2

Based on streetview, construction has been a two year process.

These intersections sucked for everyone. Massive crossing for pedestrians, nothing for bicycles, and horrendous congestion for drivers making left turns because Mass Ave didnt stop.

The weird circle things were simply confusing.

They also knocked down a house to add a new entrance to the Minuteman trail
https://goo.gl/maps/PLWxmvM6sK52

On the downside, apparently they hired a highway engineer because the turning radii they put in could handle a semi truck at 85mph. WTF

Engineering plans:
https://www.lexingtonma.gov/engineering/files/east-mass-ave-final-plans-9-27-16

Article:

A pair of new traffic lights that have loomed over Massachusetts Avenue in Lexington for months will soon be turned on.

Reconstruction of a stretch of road along Massachusetts Avenue - the project of which the lights were a part - is entering its final stages and is projected to be completed on schedule and slightly under budget, according to MassDOT.

The project, which encompasses roadway from Marrett Road to Pleasant Street, is aimed to improving safety conditions at three intersections in the area. It included consolidating some uncontrolled mid-block crosswalks, improving bus stops and providing bicycle accommodations, according to MassDOT’s website. The project is scheduled to be completed in late fall, and is projected to cost about $4.2 million, Victoria Mier, communications assistant for MassDOT said in an email. The project’s original budget was $4.5 million.

Sidewalks still to come

Construction is currently being done on sidewalks on Marrett Road and on Massachusetts Avenue eastbound from Marrett Road to Maple Street, Mier said.

“The primary work items that remain include the installation of the remaining sidewalks, landscaping, activation of new traffic signal systems, and miscellaneous clean-up items,” Mier said on July 6.

Ross Morrow, Lexington’s assistant town engineer, said the project is about 75 percent finished.

“I think they’ve got quite a solid bit of concrete work to do,” Morrow said. “I would say the majority of this month will be pouring concrete sidewalks and driveways.”

Right now the sidewalks are essentially a “gravel walk area” and has been “for a while now,” Morrow said.

“It will be nice to get the concrete back in place,” Morrow said. “We’re dealing with it the best we can.”

One traffic light remaining

Along with new sidewalks, the project also includes two new traffic signals on Maple and Pleasant Streets, Morrow said.

“It’s in Eversource’s hands right now,” Morrow said.

Michael Durand, a spokesman for Eversource, said the work is expected to be completed soon.

“We connected one set at Maple (Street) and Mass. Ave. We have one other set to connect, pending the wiring inspection,” Durand said on July 10.

Morrow said the project is still on schedule to be completed by late October.

“That includes all sorts of cleanup,” Morrow said. “Once everything’s in place and active, the contractor will still have to go through (and) clean out the catch basins and do final seeding of any disturbed areas, stuff like that.”

http://lexington.wickedlocal.com/ne...plete-on-mass-ave-traffic-lights-in-lexington

Hope theyre on when I visit in a few weeks.

 

[North Shore]

On the downside, apparently they hired a highway engineer because the turning radii they put in could handle a semi truck at 85mph. WTF

Hi, Professional Traffic Engineer here.

God forbid an engineer design geometric improvements in order to accommodate a WB-series truck for a design speed of 30 or 35 MPH for roadway intersections that are not 90 degrees and such that the truck will not encroach into the opposite lanes, thus avoiding a potential collision situation.

 

[jass]

Hi, Professional Traffic Engineer here.

God forbid an engineer design geometric improvements in order to accommodate a WB-series truck for a design speed of 30 or 35 MPH for roadway intersections that are not 90 degrees and such that the truck will not encroach into the opposite lanes, thus avoiding a potential collision situation.

Sounds like you are behind on your PE credits because this is incredibly outdated.

No, a truck does not need to move at 35mph to make a turn, especially from a residential street where the only larger vehicles that will show up are for a construction project.

And it is absolutely fine for a truck to encroach into the opposite lane when it is such an uncommon movement.

If an intersection sees 2,000 movements an hour, you do not design for something that happens .01 times an hour.

This isnt an interstate off-ramp, it is a turn onto a low-density residential roadway, adjacent to a popular multi-use trail.

 

[North Shore]

Sounds like you are behind on your PE credits because this is incredibly outdated.

No, a truck does not need to move at 35mph to make a turn, especially from a residential street where the only larger vehicles that will show up are for a construction project.

And it is absolutely fine for a truck to encroach into the opposite lane when it is such an uncommon movement.

If an intersection sees 2,000 movements an hour, you do not design for something that happens .01 times an hour.

This isnt an interstate off-ramp, it is a turn onto a low-density residential roadway, adjacent to a popular multi-use trail.

Rather than try to insult my intelligence and use fictional numbers to make an argument, I'm going to use real numbers by looking at the cover sheet of the design plan set and focusing on the "T" column. That's your percentage of trucks as part of the overall daily and peak traffic volumes.

For Mass Ave. and Pleasant Street (routes 4 & 225), both principal arterials and Maple Street (route 2A), a minor arterial that collective carry the bulk of the traffic volume, the percentage of trucks varies between 3.6% and 4.6% during the peak hour and 4.2% to 7.5% on an average day. Those are fairly high numbers for those classifications of roadways to begin with and you're dealing with an urban (developed and relatively constrained) area on top of that. So, for those 3.6 percent of trucks (let's go low end) that use Mass Ave. during the peak hour, encroachment is a huge deal.

Truck volumes play a big part in dictating geometry and pavement design.

Far too many times, we read about trucks that hop corners and/or ride up on curves and injure pedestrians and bicyclists. It is our responsibility to make sure we use the compiled data to design a safe intersection, guided by AASHTO and MassDOT guidelines. Failure to do so opens us up to immense liability.

 

[jass]

Rather than try to insult my intelligence and use fictional numbers to make an argument, I'm going to use real numbers by looking at the cover sheet of the design plan set and focusing on the "T" column. That's your percentage of trucks as part of the overall daily and peak traffic volumes.

For Mass Ave. and Pleasant Street (routes 4 & 225), both principal arterials and Maple Street (route 2A), a minor arterial that collective carry the bulk of the traffic volume, the percentage of trucks varies between 3.6% and 4.6% during the peak hour and 4.2% to 7.5% on an average day. Those are fairly high numbers for those classifications of roadways to begin with and you're dealing with an urban (developed and relatively constrained) area on top of that. So, for those 3.6 percent of trucks (let's go low end) that use Mass Ave. during the peak hour, encroachment is a huge deal.

Truck volumes play a big part in dictating geometry and pavement design.

Far too many times, we read about trucks that hop corners and/or ride up on curves and injure pedestrians and bicyclists. It is our responsibility to make sure we use the compiled data to design a safe intersection, guided by AASHTO and MassDOT guidelines. Failure to do so opens us up to immense liability.

Pleasant gets higher truck volumes because it is a direct connection between Route 2 and a commercial area on Mass Ave.

Maple does not connect to anything that you wouldnt be better off arriving to from a different direction if you are a truck. You should not design for a use that is incompatible with the roadway and neighborhood because some truck driver wants to take an off-map shortcut using an inappropriate vehicle.

There are many choices that can be made. A sweeping turning radius is the easiest way to accommodate trucks, but does so at the expense of all other users.

You can accommodate the turns by setting the stop bar back.

You can also simply ban larger trucks from making the turn, and send them to a more appropriate roadway. If a truck is riding up onto the sidewalk than the driver need their license removed. They should be on a truck route or in an appropriate vehicle.

 

[bakgwailo]

All fine and good until a truck right hooks and kills someone (again).

 

[sm89]

All fine and good until a truck right hooks and kills someone (again).

Another traffic engineer chiming in here-

I'd be more concerned with a heavy vehicle rounding a corner at 35mph than one going at 5mph jumping the curb twice a year because they misjudged the turn. This could also be addressed with a few bollards.

When you widen a curve radius there are two main things that cause it to screw over pedestrians:

1. Lengthens the crosswalk- This means you need more crossing time and also more pedestrian clearance time (flashing don't walk). Giving the crosswalk more time "takes time away" from the vehicle phases. To compensate for this, they often make you use the crosswalk button instead of having a walk phase every cycle (on recall). A wider curb radius also makes a concurrent crosswalk a poor option as drivers don't slow and yield when the geometry doesn't force them to.

2. A larger curb radius often pushes the ramps and crosswalks further down the intersecting streets to allow for the ramps to align properly (for ADA compliance). This adds a lot of extra steps and most people then cross outside the crosswalk so they aren't inconvenienced.

 

[Justin7]

I'm fascinated by the philosophical differences between the traffic engineer in Somerville and the traffic engineer with the pseudonym "North Shore."

 

[North Shore]

Pleasant gets higher truck volumes because it is a direct connection between Route 2 and a commercial area on Mass Ave.

Maple does not connect to anything that you wouldnt be better off arriving to from a different direction if you are a truck. You should not design for a use that is incompatible with the roadway and neighborhood because some truck driver wants to take an off-map shortcut using an inappropriate vehicle.

And if you want to be the designer who gets sued because that one truck following Waze went down a street , hopped a curb and ran over a kid - well, have fun with that.

There are many choices that can be made. A sweeping turning radius is the easiest way to accommodate trucks, but does so at the expense of all other users.

You can accommodate the turns by setting the stop bar back.

Setting the stop bar back means reducing the storage capacity of the turn lane, which in turn eliminates a huge benefit of the redesign. Those MUTCD sample looks great and all, but when you have to shoehorn a functional design into a developed urban location, there are significant limits as to what you can and cannot do.

You can also simply ban larger trucks from making the turn, and send them to a more appropriate roadway. If a truck is riding up onto the sidewalk than the driver need their license removed. They should be on a truck route or in an appropriate vehicle.

Except you can't. Having worked for a local municipality in the past and in my current job, truck bans are a long and complicated process. The reality is that towns can't say "no trucks', even with an alternative route. The vast majority of those signs that you see today are not enforceable in a court of law.

 

[North Shore]

I'm fascinated by the philosophical differences between the traffic engineer in Somerville and the traffic engineer with the pseudonym "North Shore."

Grew up in Peabody. Have worked in Gloucester, Reading, Billerica and Marlboro.

 

[jass]

2. A larger curb radius often pushes the ramps and crosswalks further down the intersecting streets to allow for the ramps to align properly (for ADA compliance). This adds a lot of extra steps and most people then cross outside the crosswalk so they aren't inconvenienced.

In this case, the traffic engineer didnt give half a shit about ADA best practices, as the ramp to cross Mass Ave is in no way shape or form aligned with the crosswalk.

https://goo.gl/maps/f8ijwL5feww

This is also obvious in the construction diagrams.

Makes you wonder how much they really care abut really designing a safe intersection.

And if you want to be the designer who gets sued because that one truck following Waze went down a street , hopped a curb and ran over a kid - well, have fun with that.

Thats not how liability works, at all. You are immune from liability if you follow previously endorsed plans. That means MUTCD, AASHTO, and NACTO. Those plans absolutely allow you to accommodate rare truck movements through a variety of techniques that do not require a massive turning radius.

And frankly, it's pretty obvious what you care about when you say this:

Setting the stop bar back means reducing the storage capacity of the turn lane.

Im sorry, I thought our primary concern was the truck turning without killing Jimmy? I guess Jimmys life is secondary to storage capacity.

So again, why are you not concerned that a blind pedestrian is being oriented diagonally into the intersection where he will get run over, thanks to the incredibly large turning radius?