Proper method for measuring angle of intersection of two streets

[DeanVesuvio]

I am involved in an appeal based on a city whose planning code indicates that the angle of intersection of two streets controls the nature of the lots bounded by those streets.

The streets in question form a "T" intersection. The through street follows a curved path at the point of intersection, while the terminating street is straight.

I am trying to determine the proper way to measure this angle of intersection. I believe the proper methodology is to compute a tangent line to the curved street at the point of intersection and then measure an angle between this and the midline of the straight street.

I'd be interested if anyone has worked on a situation like this, and if so could you direct me to some online or offline resources which indicate the proper methodology for a measurement of this kind?

Thanks much,

Dean

[subman]

Please try to elaborate and provide another example if it is not. CL of tee street tends to be radial to curved CL to optimize sight distance at intersection. Lot lines along the curved street would tend to be radial to the CL curve with at least minimum lot width at the street side line. Corners lots would have unparallel lot lines. One being the street sideline, parallel to the tee street CL and the other being on a radial bearing to the curved street CL.

[DeanVesuvio]

Attached to this post is a map of the intersection in question.

The relevant intersection is the one between "Pine Needle Drive" and "Broadway Terrace at the top-right edge of the map. Notice that the through street (Broadway Terrace) is curved at that location, while Pine Needle is fairly straight.

The stop sign in the intersection is just about at the top of the text "R.156.44" which runs along the lot line of the lot to the southwest of the intersection.

[DeanVesuvio]

To be completely clear, the lot in question is the one to the left of the intersection -- it is marked with the numbers "39" and "40." City staff has deemed this an "interior lot" based on the argument that the angle of intersection of the two streets is more than 135 degrees. We are arguing it is a "corner lot." To defend this position, we need an understanding of the proper way to measure the intersection angle.

[Jim Frame]

Wouldn't the design geometry be defined by the two maps? It seems to me that an Assessor's Parcel Map is the wrong instrument to be looking at to solve the problem.

For what it's worth, a visual inspection of the AP map indicates that Broadway Terrace isn't radial. But the subdivision map (or whatever document created the Broadway Terrace ROW) would tell the tale, wouldn't it?

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[DeanVesuvio]

The city planning staff did use a subdivision map instead of the assessor's map. But there is no angle indicated on that map. Instead, planning staff drew their own lines and used a protractor.

I do not have an electronic version of the subdivision map at the moment, but it is very, very similar to the map I posted.

What I'm curious about is how such angles are typically determined at the time a subdivision is laid out. Is the controlling line the tangent line to the curve or some other line?

[subman]

-- Lot, Corner. “Corner lot” means a lot or parcel of land situated at the intersection of two or more parkways, highways or streets, which parkways, highways or streets have an angle of intersection measured within said lot or parcel of land of not more than 135 degrees.


Try using the side line bearings S 70-38-45 E and N 36-41-35 W and I think you get an anle of 134-02-50 which would qualify as a corner lot in my opinion (i.e. not more than 135 degrees).

But then I am not a Planner...

[DeanVesuvio]

Dennis -

Thanks for the helpful reply. That methodology is essentially what the planners are using. It's interesting that you came up with a number under 135. That in and of itself is very helpful, and I like how you used the bearings of the lot lines to support that.

But, I'm curious if there is any technical/formal way in the surveying literature for how this should be measured. I ask because it seems likely to me that such a methodology would make use of lines tangent to the curves of the roads.

[subman]

Sorry, tried adding in my head. Just checked with the HP48gx and it is really 144-02-50 > than 135 degrees

[DeanVesuvio]

Our definition is slightly different from yours. It makes no mention of "within said lot or parcel of land":

“Corner lot” (see illustration I-1) means a lot bounded on two or more adjacent sides by streets, by private ways described in Section 17.106.020, or by portions of such streets or ways, having an angle of intersection of one hundred thirty-five (135) degrees or less.

This is what leads me to the question of the proper way to measure an intersection of two street lines. I feel like there must be a "right" way to take such a measurement.

I assume the original subdivision recorded lots 39 and 40 are now 'merged' into one ownership? I view the original lot 40 as an 'interior' lot, not a corner lot. Lot 39 is a corner lot. If the two lots were to be legally 'merged' into one lot, then there would be no debate that the resulting parcel would being considered a 'corner' lot.

It has not been explained (at least I am missing something) why only lot 40 is being argued (appealed) for a 'corner' verses 'interior' lot designation. I can only assume that the owner is trying develop it and/or sell that portion or parcel?

I have platted a LOT of subdivisions through the years (5 lots to 600+).
I can not see how it can be argued as anything other than the original plat's intent that lot 40 was a fronting interior lot.

[DeanVesuvio]

David -

The situation is rather complex. The lots were merged long ago. City planning staff has declared the combined lot an interior lot.

I wonder why you think there is "no debate" that the resulting lot should be a "corner lot." And, do you have any thoughts on this issue of computing the angle of intersection of the two streets?

In any case, the city is using the interior lot thing as a justification for deeming the entire curved northern lot line as a "front lot line," which may have the consequence of moving the rear yard setback from the southwestern corner to the southeastern corner of the lot (or perhaps even eliminating the rear yard altogether).

Safe access to the lot is only available to the lot from the eastern side, as the road slopes much more steeply than the lot from east to west. And, every other lot along the ridge south of the lot in question has its rear yard on the western side of the lot.

Our goal is to revise the decision such that the short section of the lot along Pineneedle is deemed the "front lot line," with the curved section along Broadway Terrace deemed a "side lot line," along with the other "side lot line" to the south.

[PE_PLS]

Someone asked about the sub map, a portion of which is attached...

Dean-

I did make too many assumptions, and not having all the information is never a good way to make final or correct assessments.

I referred to the merged lot as a corner lot due to the approximate 90* corner at the NW roadway alignment change ("Terrace on the west and north), disregarding the 'T' intersection. Hence my previous question: From a pure platting view, since original lot 39 is a corner lot (based upon the ~ 90* angle), why should not the merged 39/40 be treated the same? However, your topography explanation is certainly helpful in understanding the potential for the city planning staff's opinions. BTW: is using the west side of lot 39 really inaccessible due to slope issues (ie exceeds current development standards), or only economically prohibitive to the client?

If the access issue is merely prohibitive, I would still question )in my own mind at least) the City's logic on perhaps the following basis: If lots 39 and 40 were still separate lots, and a builder was pursuing permits, which side of lot 39 would be considered the 'frontage', 'side yard' and 'rear yard'?

Of course, then there is the utility servicing (sewer access, water, power, etc). Alas, too many questions ... lol

[Jim Frame]

I thought those street names sounded familiar! The site is about 2 miles from where I grew up, though in a neighborhood I rarely had cause to enter.

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Per the original map (kindly provided by PE PLS), I still believe that were the 2 lots still separate parcels: 1) Lot 40's entire street face (arc and line) COULD be considered the frontage, while Lot 39 would be considered a corner lot and most likely have the straight portion of the lot identified as the frontage. However, another thing to consider in Lot 40 only is the relationship of the bearings of the north (street face) and southerly (common with lot 38-A) straight lines. They are only 29*08'45" out of parallel. From a development platting and house fit perspective, it would seem mathematically logical to me that the southerly line (105') is better suited for a side yard than the westerly line (88'). But that is entirely dependent upon a proposed foot print.

Of course, the requirements for developing these lots today are significantly different than what was approved and permissible at the time of recording.

[DeanVesuvio]

David -

The west side of lot 39 is probably only inaccessible due to economic limitations. The slope is extremely steep, but in this area of the Oakland hills, plenty of lots like that are developed.

There is little question in my mind that if 39 and 40 were still separate, the line dividing the two lots would be where each lot's rear yard would be sited.

The issue we confront here is that, in practice, only lots 36A, 37A and 38A are developed, and lots 39 and 40 are merged.

The developer is seeking to site a house largely on the 39 section of the merged lot, and to place the rear yard in the 40 section -- which is where the driveway, utilities and level access are located.

This is obviously a problem for the neighbors, as the siting places this one house several dozens of feet in front of all the other houses along this section of roadway.

[DeanVesuvio]

David -

The truly odd thing that city staff has done thus far here is to declare that the *entire* curved boundary is the frontage. That leaves only the straight boundary to the south as a side lot line.

This determination causes all sorts of mischief, as city code defines things such as the "lot width" as the distance between the "side lot lines." Since staff has determined there is only one side lot line, we are left in a situation without clear guidelines.

Our hope is to find a basis for splitting the long curved northern boundary into a "front lot line" and a "side lot line," which will solve this problem.

Dean-

Good luck with it. Looking at the official plat, I only see two curved areas on both lots 39 & 40. Me thinks you are not going to win on the 135* angle issue though.

[DeanVesuvio]

Thanks for the feedback. I'm not sure what you mean about "only seeing two curved areas." The point I was trying to make is that, since 39 and 40 have been merged into a single lot, the city is viewing the combined curved line starting at the eastern edge of 40 and terminating at the western edge of 39 as a single "front lot line." This is very unusual as it produces a lot with only two lot lines. Nearly all of the planning code is based off lots with three or more lot lines.

Dean-

If you look at the subdivision plat (not the assessors parcel map), lot 40's frontage is not a continuous curved line. This assumption would be erroneous on the city's part. The front lot line begins on the far easterly end as an arc (90') and then becomes a line (50') until it meets the common 39/40 lot line. (See ,y attachment)

I would agree that the city is dealing with a rare situation (but not uncommon in the Bay Area), and they should be open minded enough to realize that not every lot fits into their 'perfect' little box, ie lot definition ordinance.

Hopefully, you can at least have them admit this and it can logically and fairly work towards the good of the client. But good luck. Often times one needs to bypass the technical staff and speak directly to the department heads.

[Anthony Maffia]

I'm not sure what the answer is, but questions come to mind.

1. Were the lots merged legally or not? Planning may be wrong.

2. What stood on the parcel(s) prior to the fire?

3. Google Earth shows a concrete slab in the shape of a home. Did the city revoke a building permit?
http://img693.imageshack.us/img693/1066/pineneedle.jpg

4. I had a friend who lived half a block from there, tried to do something after the fire and the city said, "financial restrictions don't matter, if you can't afford to build there, then you shouldn't have bought the lot."

5. Special situations require that you talk to a supervising planner.