Tag Archives: arterials

How Does Your Grid Grow?

Every city has an underlying historical layout that shapes growth. For example, New York is dominated by a continuous grid of avenues and streets, first deployed in Manhattan in the early 1800s, then repeated again and again in Brooklyn and Queens. In Boston, development is shaped around “squares” (which might more properly be called “crossroads”), along the major roads connecting the squares, and then into local grids of varying regularity.

In Los Angeles, development is shaped by a grid of north-south and east-west arterial roads, generally on half-mile spacing. The grid is somewhat distorted by topography and historic land grants, such as the old pueblos and ranchos. While some areas have New York-style continuous grids in between the arterials, much of the city has features such as irregular grids, curvilinear streets, and jogs in the grid, all of which discourage through traffic and transit. This reinforces the importance of the arterials.

Navigating a city requires forming an internal map of this structure – where the roads go, and how well they do it. For example, if you spend a lot of time in the Inland Empire, you probably know Milliken, Haven, and Archibald, and which one isn’t continuous around Ontario Airport. If you live on the Westside, you know Pico, Olympic, Santa Monica, and Wilshire, and which ones will ruin your bus ride in the afternoon. In Boston, you might know that Somerville Ave takes you between Porter Square and Union Square, while Cambridge and Washington Streets take you between Union Square (Allston) and Oak Square. On the other hand, Manhattan’s continuous grid devalues knowledge about the east-west streets; you’re better off knowing the major streets and the few areas where the grid is disrupted, like Morningside Park.

When I started posting about north-south transit on the Westside, I found that I didn’t really like any of the readily available maps. For my eye, Google Earth and Maps are too busy, while highly stylized maps, like LA Metro’s system map, are too distorted. I wanted a map that was roughly geographically accurate, but stripped down enough to show the underlying structure. So I made my own map of the mile-spaced arterials, scaling distances in Google Earth and drafting in CAD. The original plan was to just do the Valley and the LA Basin, but I ended up doing all five LA area counties (LA, Orange, San Bernardino, Riverside, & Ventura).

This exercise was very revealing because it shows how much editorializing is involved in mapmaking. While maps are often presented as unbiased fact, the content is strongly influenced by the personal, social, and cultural background of the person making the map. Even on this map, which only includes streets, we must decide which streets are important enough to be included. As suburbia faded to desert in the Antelope Valley and farms in the Coachella Valley, I kept putting in the arterials as long as they were paved. Do Avenue A and Hayes (named for Rutherford B Hayes in one of the most extensive presidential street grids you’ll find) really belong on the map? You tell me.

This map only includes arterial roads. There are no freeways and no rail lines. Yet if you know LA’s geography, you can probably pick out many regions by their arterial structure – the regular grids of the Valley, the LA Basin, northern Orange County, and the Coachella Valley; the growth-boundary-stunted grid of Ventura County; the irregular layout of hilly areas like the Santa Clarita Valley and southern Orange County; the established grid of the older San Bernardino County cities and nascent grid of the newer Riverside County cites; the ill-defined edges of growth in the High Desert. You’ll also see features from where there aren’t roads, like the immense expanse of the San Gabriel Mountains. And finally, you might see things you didn’t realize before, like the oddly distorted north-south arterials between Main and Cherry in the LA Basin.

Despite showing only arterial roads, the map can be read in many ways depending on your point of view. Does the anticipatory grid in the Antelope Valley portend endless sprawl, or room for opportunity? Or is the lonely view along 200th Street E to Hi Vista that and nothing more? What about golf courses and subdivisions creeping southeast into the farms of the Coachella Valley?

Anyway, enjoy. Click to embiggen. . .



Compete With Arterials, Not Just Freeways

In the US, we often mentally organize cities by their freeways, and consequently we often conceptualize potential transit as mimicking the freeway network. Hence we think of north-south transit between the Westside and the Valley as “the 405 Line”.

But as Cap’n Transit would remind us, transit is competing with parallel facilities like freeways. If the freeway is a total basket case, like the 405, you’ll probably do fine. But in a place like Orange County, even the heavily traveled freeways are going to offer faster average speeds. Where transit and freeways compete, freeways often come out on top, partly because medium distance trips are the sweet spot for freeways – trips that are long enough to make freeway access time worth it because of the higher speeds freeways offer.

However, transit is also in competition with arterial roadways, mostly for trips for which freeways can’t compete. These are shorter distance trips, where it’s not worth the time to get to and from the freeway, as well as medium distance trips where there’s no freeway available. In fact, even in LA County, the best performing LRT lines are the ones that are not directly in competition with a freeway: the Blue Line is somewhere between the 110 and the 710, and Expo Line Phase 1 is about a mile from the 10 (and benefits from the truly abominable traffic). Meanwhile, the lines that directly compete with a freeway (the Green Line and the 105, the Gold Line and the 110) achieve fewer boardings per mile.

It follows that we could find some clever and unexpectedly successful LRT or BRT routes by looking for long, straight arterial corridors that are serving short distance trips and medium distance trips where there’s no freeway available. In fact, we already saw a couple such potential routes when we looked at Sepulveda Pass/LAX transit: Reseda, Balboa, and Lincoln are long arterial corridors where there’s no practical competing freeway.

Where else do we have potential corridors like this? Here’s a few that come to mind:

  • Beach from Huntington Beach through Westminster and Stanton to Buena Park (or maybe La Habra)
  • Harbor from Newport Beach and Costa Mesa through Garden Grove and Anaheim to Fullerton (or maybe La Habra)
  • Florence from Westchester through Inglewood, South LA, Huntington Park, and Bell Gardens to Downey
  • Lakewood from Pico Rivera through Downey, Bellflower, and Lakewood to Long Beach
  • Hawthorne in Torrance
  • PCH from LAX to Long Beach
  • Imperial from Norwalk through La Mirada and Brea to Yorba Linda
  • Whittier from East LA through Montebello, Pico Rivera, and Whittier to La Habra
  • Azusa from Industry through Covina to Azusa
  • Rosemead from South El Monte through Rosemead and Temple City to East Pasadena


At the moment, I’m finding the first two the most intriguing. The others are good candidates for sure, but I like the idea of a sneaker route in Orange County, connecting the beaches to Metrolink. Beach is a good five miles from any competing north-south freeway. Harbor probably has better destinations but is closer to the 55 and the 57.

The problem to watch out for with routes like this is making sure there’s enough development to justify the route. Odds are the biggest destinations have freeways between them, but you can still find routes that make sense. I may revisit one or several of these corridors in more detail in the future.