topology , reliability, intersection princiables

Question 1

name two diffferent types of network topology and their main charactersirtics

Answer 1

Grid - road heirachy less defined, x intersections

tributary- closed network T intersection, volumes easier to estimate

Question 2

how could you turn grid into tributary and vica verse

Answer 2

grid–>tributary close access to raod at one end
tributary->grid provide access ways for bikes etc throug parks, - hence has better permeability for active modes making them more desireable for neighbourhood trips

Question 3

3 ways to reduce speed on road

Answer 3

-curvilinear design ( curvy road etc, reduces SSD)
-vertical displacement devices
-more intersections
however all may reduce flow rate

Question 4

what are two other types of topology (not as major)

Answer 4

fused grid,

new urbanism- promotes walkable neighbourhoods in a grid style

Question 5

what are the 6 types of routes (eg tree)

Answer 5

tree, ring, mesh, line, star, full connected. (see pictures)

Question 6

what are the two types of unrealiabnility for a road

Answer 6

route closed. and route open but slow

Question 7

what are the 5 types of intersection control and what types of roads are they used for

Answer 7

uncontrolled (minor roads)
priority (give way/stop) minor roads
roundabout (roads with similar hierarchy 
signalized (major) 
grade separation (very major)

Question 8

what are the 10 principles of intersections

Answer 8

1 ensure adequate capacity and appropriate control form
2 reduce conflict points ( crossing diverge converge (make T intersection as they have fewer)
3 minimize area of conflict (fix by kerb channelization)
4 separate conflict points (by channelization)
5 give prefeference to major flows
6control vehicle speeds (dont want high relative speeds at crossings)
7 clearly define vehicle path (channelization and lane marking)
8 provide adequate sight distance
9 ensure form of control is clear to users, (prority must be clear, lots of signs and shit)
10 provide for all users (special road user lanes, crossing facilities )

Question 9

what is the down side of channelization?

Answer 9

obstruction, restricts parking drainage problems.

Question 10

what are the roundabout design principles

Answer 10

adequate entry widths
central island diameter sufficient to guide drivers 
control speeds (30 kmh ideal)

Question 11

what causes more accidents, Left or right staggered T intersections?

Answer 11

Left has more accidents, (about 67% more )