TCD's (3 types)

-traffic markings

- " signs

- " signals

-Regulatory (white, red, black)

-Warning (yellow)

-Guide

P- Passenger

B- Bus

SU- Single Unit Truck

WB-50- Wheel base 50 feet

constant for conversion between mph and ft/s

comes from 5280 ft/3600 sec

used for timing signals

4.0 ft/s

3.5 ft/s used where older ped's are predominant

Limited-access facilities (freeway)

Arterials

Collectors

Local Streets

see pg. 36 for figure

Circular

P.I. = point of intersection

P.C. = point of curvature

P.T. = point of tangency

T = length of tangent

E = external distance

M = middle ordinate distance

L.C = long chord

delta = external angle of curve

R = radius of the curve

see figure 3.6 p. 42

T.S. = transition station from tangent to spiral

S.C. transition station from spiral to circular curve

C.S. = " circular curve to spiral

S.T. = " spiral to tangent

Delta = angle of defl (central angle) of orignal curve

Delta s = " of circ. portion of curve w/ spiral

delta = angle of deflection for spiral portion of curve

Ls = length of the spiral

-2 consecutive horiz. curves in opposite directions

-always separated by a tangent of at least 200 ft- to allow for correct superelevation

-Shaped like parabolas

VPI = vert point of intersection

VPC = vert point of curvature

VPT = vert point of tangency

G1 = approach grade %

G2 = departure grade%

L = length of vert curve, in hundreds of ft

travel = 12 ft

shoulder = 2-12 ft

All lights are red

-good for safety, bad for flow

Guardrails

"Texas Twist"

"Boxing glove"

JMB

-buried in the ground- this was launching cars off the road

-newest - spiral on the ends then wood after that

-Jersey median barrier - concrete most common now

1. Fulfill a need

2. command attention

3. convey a clear, simple message

4. command respect of road users

5. give adequate time for proper response

- how they look/are constructed

-placement

-warrants or conditions that justify a device

-color

-shape

-pattern

-legend

Longitudinal - parallel to direction of travel

transverse markings - any marking cuts across portion of traveled way (all white)

object markers

-long. and transverse are most commonly paint and thermoplastic - reflectivity is achieved by mixing tiny glass beads in the paint

Yellow - separate traffic in opposite directions

White - Separate traffic traveling in the same direction

Red - roadways that will not be entered

Blue - parking spots reserved for people w/ disabilities

Black- used with other markings on light pavements to emphasize other colors and patterns

line markings- 4 to 6 inches wide

Wide lines - twice that for emphasis

Broken lines- 10 ft line segments, 30 ft gaps

Dotted lines- 2 ft lines, 4 ft gaps

- on all paved urban arterials that are 20 ft or more and an avg daily travel of 6,000 veh/d or greater

-also any pavedd two way streets with 3 or more traffic lanes

-STOP Width = 12-24 inches

-Yield line = triangles across the lane see fig 4.3 p.71

-Min Dimensions 12x18 in. (bxh)

-Max Dimensions 24x36 in.

rate of flow is an estimate

volume is an actual count

both in veh/hr

ADT = average daily traffic

AADT = avg. annual daily traffic

-Do not count A.M. Monday or P.M. Friday

-Peaks are A.M. and P.M. (mini peak at noon)

-Design Hourly Volume

-Directional Design Hourly Volume

Peak Hour Factor

the relationship between hourly volume and max rate of flow within the hour

-SMS < TMS Always

-Only equal if everyone is going a constant speed at the same speed

- They weigh slower cars more with SMS

-renowned T.E. in the 1930's

-Volume, density, speed

-angle or parallax observation problems

-Manual operation of stopwatch

-Automatic Traffic Recorder

-Where "speed trap" comes from- being "trapped" between two ATR's

-by video camera

-disadvantage is that its tedious for someone to watch all the video

-manual studies

-semiautomated studies

-fully automated studies

-closed end tube where pressure is maintained

-counts axles

-problem is that they count axles

-need to use avg number of axles per vehicle

-Electromagnetic induction (inductive loop detectors)

-overhead microwave radar detector

-traffic volume counts

-control counts are permanent continuing counts

-coverage counts are more of sample counts

cordon

screenlines

imaginary boundary - usually a loop of interstates- around a CBD (40,440,65,24)

screenlines break up cordon into smaller areas

-good ex.'s are rivers and railroad tracks

volume = # of veh's passing study location in the hour

demand = volume + veh's wishing to pass the site during the hour but couldn't due to congestion

capacity = max volume that could be accomodated by the highway at the location

12

through, right, and left at each leg

Vehicle Miles Traveled

-This has gone up but fatalities have still gone down

-property damage only (PDO)

-injury

-fatal

-occurence of accidents at the location in question

-env. and physical conditions at the location

collision = schem. representation of all accidents

condition = describes all physical and env conditions

-space length = 18'

-space width = 9'

-module length = 60-61' (space aisle space)

-total number of vehicles parked at any given time

-duration = length of time individuals remain parked

-No signals or stopsigns

-controlled access

-LOS

-vehicle mix

ideal = basic capacity (under ideal conditions)

possible = similar to the current capacity

practical = most similar to volume for LOS C

-v/c

-volume

-density

-speed

-delay

no heavy vehicles in traffic stream

driver pop. dominated by regular users of facility

operational (planning)

service flow rate (LOS under magnifying glass)

design (number of lanes)

-length of weaving area

-width or number of lanes

written by AASHTO

-A geometric policy on design of highways and streets

Average Travel Speed

-avg speed of all vehicles on a segment of highway for specified time period

-electronic

-size (older drivers)

-reflectivity

wire

post

mast arm