How can two street systems be designed to be co-extensive yet non-intersecting? In abstract geometric terms, the solution is two parallel radial/ring networks (Figure 24.1): a system of LLM streets (depicted in blue) that extend outward from the town center, interlaced with a system of FHV roads (shown in red) that radiate inward from a circumferential outer beltway. This enables two universally accessible yet completely separate travel networks and, furthermore, generates what many consider to be an ideal small town—one
A fully featured LLM is a mini-car that is just like a conventional FHV except that it is smaller and slower: it has a completely enclosed cabin, full and comfortable seats, adequate leg room and storage space, air conditioning and heating, entertainment systems, a smooth quiet ride, good handling, power steering, power braking, power windows and door locks, a responsive and reliable motor, an attractive design, and robust construction. In the cost analysis, the cost of an LLM mini-car is estimated with all of these features.
containing a commercial town center, high-density residential living immediately outside the center, and low-density living space on the outskirts.
The entire town lies within an outer, high-speed beltway for FHVs. A central LLM road rings the commercial and civic center of the town. The town center, like the neighborhood areas around the center, is accessible to FHVs as well as LLMs. Between the outer FHV beltway and the central LLM ring road, neighborhoods are built that are accessible everywhere to FHVs and LLMs. The LLM streets all radiate outward from the LLM ring road around the town center, and the FHV roads radiate inward from the FHV beltway around the entire town. The LLM street system includes separate bicycle and pedestrian paths in some places. The two networks service every individual location but never intersect.
The town center, the area inside the central LLM ring road, contains most of the shops, schools, offices, churches, civic buildings, intercity transit stations, and other commercial and retail spaces. The radial LLM streets feed into the central ring road and provide direct, LLM-only access from all neighborhoods to all areas in the town center.
The residential neighborhoods begin on the outside of the central LLM-ring road, with high-density multifamily dwellings closest to the town center and large-lot single-family homes furthest. This traditional pattern of decreasing density is repeated along each LLM "branch" radiating out from the LLM ring road. Again, the two networks serve all households, but never intersect—every property has access to an LLM road in one direction and an FHV road in another (Figure 24.2). Each major radial "branch," comprising one major LLM/ FHV pair, functions socially as a neighborhood, with a neighborhood park, neighborhood school, public gardens, and a few neighborhood shops.
Every place within the town (i.e., home, business, and public area) either "faces" the LLM community network and "backs" onto the FHV network, or else borders one of the road systems (LLM or FHV) and shares a driveway that leads to the other system (Figure 24.3). The FHV roads that radiate inward from the outer high-speed beltway interlace with, but never touch, the LLM streets that radiate from the town center. The idea is to have the FHV roads remain on the "backs" of housing units, rather like service alleys, and the LLM streets to be on the fronts, like community paths or streets. Private driveways connect both of the networks with private garages or parking areas.
FHV roads serve two primary functions: (a) they provide households direct access, via the outer beltway, to outside of the town, and (b) they provide persons and goods from outside the town direct access to the inner civic,
commercial, and service core of the town center, via two or three FHV roads that penetrate all the way to the town center. These penetrating FHV roads go underneath the central LLM ring road and come up into roads and parking areas on the "back" side of businesses, offices, schools, etc. In contrast, the primary function of the LLM streets is to provide access inside the town—in particular, to and from the town center—via the central LLM ring road.
Thus, the FHV and LLM networks complement each other functionally: the LLM network is designed primarily for trips within town, while the FHV network is designed for all other trips. It is possible, however, to use the FHV network for any within-town trip, but the system is designed so that within-town trips are generally safer and more convenient via the LLM network. The design also provides for the possibility of extending a few LLM streets under or over the high-speed FHV beltway to connect to the LLM network of a neighboring town. However, a greenbelt between the outer FHV beltway and the ends of the LLM residential streets may be more desirable, to buffer the residential areas from the noise and unsightliness of the beltway, and to delineate boundaries.
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