March 17 Lecture Notes

1.) Determine the origin and destination of highway users: used to solve site-specific problems, location of a new bridge or for a highway bypass for a city

2.) Estimate the number using the highways: used to determine how many were actually on the roads to determine need for expansion or control. The method of choice for tabulation was automatic or traffic counters.

1. Several state highway departments in conjunction with the U. S. Bureau of Census developed a household survey to be administered randomly.

i. Made by household members 5 and older these surveys led to important transportation survey related data collection through the decennial census that today serves as the foundation for socioeconomic and economic data used in transportation planning.

ii. In addition the surveys collected a large amount of data on land-use and transportation network characteristics called inventory

2. Inventories include the physical condition of transportation facilities and the characteristics of traveler and freight movements. They identify roadway locations, roadway lengths, pavement width, speeds, parking restrictions, and in the case of transit the vehicle headways, number of seats available, and overall line capacity.

3. Even larger amounts of data are collected by numerous agencies within a metropolitan area.

1. Simple random sampling- selects units of a population so that each population has an equal chance of being drawn. Units are designated 1- N

2. Sequential sampling- draws a sample from every nth element. Based on the assumption that the target population has been listed in random order.

3. Stratified random sampling- divides the populations into subpopulations according to defining characteristics such as household income.

4. Cluster sampling- grouping sampling units, usually on a spatial geographical basis like grouping households on the basis of neighborhood blocks.

i. Each of the sampling strategies is designed to reduce bias that might come from measurement error, unrepresented sample selection, high nonresponse rates, or varying question interpretations. Cost and degree of accuracy are competing forces.

ii. The size of the sample is critical and although accuracy estimates will increase with the sample size there is a cost efficiency limit associated with increasing the sample size. Deterring the sample size can be complicated because transportation data are seldom collected for one purpose.

B. Traffic counts- validate survey data, calibrate travel demand models, establish traffic growth trends, assess the transportation impact of large traffic generators, and help to determine the impact of transportation facilities.

1. Continuous counts taken with permanent counting equipment linked to a central data processing location and can be used to establish travel trends for similarly classified roads.

3. Control or seasonal counts are used to factor traffic counts of short duration to an estimate of average daily traffic.

4. Cordon counts obtain estimates by establishing an area within a study area defined by a cordon boundary and recording movements in and out of the study area.

5. Screen-line counts use imaginary lines in a transportation network to evaluate the completeness and accuracy of estimated trips within a study area by comparing trip volumes that are predicted with those that actually do.

6. Vehicle classification identifies the different types of vehicles found in the traffic stream at specific locations.

7. Traffic weight data obtains the types and number of vehicle using it and also the weight of the vehicles.

C. Transit network performance- includes the number of vehicles in a fleet, number of seats available, measures of route utilization, speeds, and sometimes on-off passenger counts at transit stops.

1. Ride check records the number of passengers boarding at each stop and the bus arrival time at selected stops; recording data kept on vehicle.

2. Point check estimates the number of passengers on vehicle and records the vehicle arrival time. Peak loaded counts and multiple point checks include several points along a route.

4. Fare box reading electronically tabulated readings at selected route locations.

ii. Automatic passenger count (APC) technology uses pressure sensitive mats, infrared sensors, or optical imagery to estimate boarding.

D. User Characteristics have become an increasingly important component of data collecting because of policy demands being placed on the transportation planning process.

1. Household travel behavior surveys are the most expensive yet most comprehensive of all surveys. Techniques include personal home interview, telephone interview, and mail back survey.

2. Workplace and Special generator are particularly useful in targeted survey subjects like the elderly.

3. Vehicle intercept/external station surveys obtain data on the patterns of people and goods in a study area. Important to planners are trips that move a. within the study area, b. in or out of the area, c. those that pass through.

4. Panel surveys (a cross-sectional survey) follow the user over a period of time, 2 to 3 years, using a diary

5. Stated preference surveys – “given the characteristics of the following options, which one would you chose?” Asks the user to react to scenarios with which they have no experience.

6. Transit onboard surveys with handing out and collecting questionnaires, paying surveyors to do face to face interview.

E. Freight makes for a significant portion of regional trip making. 95% of trips taken by trucks are less than 200 miles in length (Census Bureau) making it predominately regional.

B. Improving the accuracy and efficiency of individual trip reporting: A study in Lexington, Kentucky showed that people tend to report start times to the nearest quarter or half –hour and that trips over five miles are often rounded off to the nearest 5 mile increment.

C. The nature of the data collected will be much of the same but the detail of information will be greatly expanded through use of Intelligent Transportation Systems (ITS). ITS is a system of information, sensor, and vehicle/network control technologies. The future of transportation planning will likely have as much to do with fiber optic and wireless communication of traffic management centers as it does with building highway or transit capacity.

1. Continuous nature of data generated by ITS removes sampling bias from estimates and allows the study of variability

2. The variability of ITS data provides the opportunity to analyze nonrecurring congestion issues, causes and solutions.

3. ITS can provide the detailed data needed to meet emerging requirements and for input to new modeling procedures.

4. As the focus of transportation policy shifts away from large-scale, long-range capital improvements and toward better management of existing facilities, ITS-generated data can support the creation of the system performance measures that are required to meet this new paradigm.

Site Impact traffic estimation refers to the impact of new development or improvement and or change of existing development, to the local transportation system. If and how will the existing infrastructure be affected is question. The more primary of the questions is will the current transportation system be able to support the change (increase) of vehicular traffic or not. If not will it be more beneficial to create new and improve the existing transportation system to accommodate the new development by adding or widening roads, intersections, maybe even new rest stops, if on a larger scale attracting people from longer distances. Or is it just not feasible to develop in the first place. Virtually all development creates traffic, and spurs economy, whether it is a new industrial area, housing, new retail business districts. The changing of one type of residential to another, such as from single family homes to condominiums, would drastically increase the population of a specific site, affecting the number of vehicular trips to and from that specific site.

The area affected by new, revitalized, or change of use development could be limited to a couple local intersections or could possibly affect an entire cities transportation system. If a mass transit system is accessible to the site this may have a positive affect on traffic if the previously other sites with the same attraction or service provided were not accessible to transit. While a traffic impact analysis will predict the number of trips to and from the specific site, the developer of the site can use the estimated numbers to plan for the internal circulation and parking needs, access/egress points, and general traffic management within the site.

-Not all development projects need an analysis on site traffic impact, generally the size of the development project and the local government “study thresholds” dictate the conduction of a study. Different areas and or various local and state governments have different thresholds for the requirement for conducting a study.

The following is a table directly from a site written by Mary Edwards, located on Prof. Goodman’s Website.

Table 3.2 Community Threshold Levels
Community/State	Traffic Impact Study Threshold

ITE Recommended Practice	- 100 additional peak hour trips
City of Farmington Hills, Oakland County	- sites with 10 or more acres and Oakland County Traffic - building with 100,000 or more sq. ft. GFA Improvement Association - 200 or more dwelling units - 300 or more peak hour trips - substantial departure from Master Plan - discretionary standards based on impact
City of Grand Blanc, Gennessee County, MI	- rezonings inconsistent with Master Plan - certain special land uses - sites with 20 or more acres - 200 or more dwelling units - 150,000 or more sq. ft.
GFA Northville Township, Wayne County, MI	- certain rezonings - 50 peak hour directional trips along selected roads - 100 peak hour trips or 750 daily trips elsewhere
City of Rochester Hills, Oakland County, MI	- 150 peak hour trips or 750 trips daily - 75 or more single family dwelling units - 100 or more multiple family dwelling units - 50,000 sq. ft. or more commercial units - 20 acres light industrial
New Jersey Department of Transportation	- 200 peak hour trips
Arizona Department of Transportation	- 100 peak hour directional trips
Maryland	- 50 peak hour directional trips
Indiana Department of Transportation (proposed)	- 100 peak hour directional trips - if LOS drops by a letter grade - modifications to roadway are required
California Department of Transportation	- 2,400 daily trips/1,600 along a congested corridor
Oregon Department of Transportation	- 500 vehicles per day
New York Department of Transportation	- 100 peak hour trips
Arapahoe County, Colorado	- 500 daily trips - certain smaller projects
DuPage County, Illinois	- whenever a development deteriorates LOS beyond community LOS Standard (C or D)
New Mexico	- all new commercial/industrial developments
Mississippi	- when a traffic signal is warranted

Source: Dey Soumya, S. and Jon D. Fricker, Traffic Impact Analysis and Impact Fees in State Departments of Transportation, ITE Journal, May 1994.

This table illustrates the varied thresholds of different regions, along with displaying the importance of a TIA of a new site of development.

These “trips” are generally calculated using a chart referencing very general land uses to size of the development, to a volume of trips per unit of measure, weather it be acres to a state park or pumps to a gas station, number of seats is a stadium, or even number of beds in a hospital. The following “trips generated” chart came from the same website as above.

Table 3.1 Threshold Levels
Land Use	100 Peak Hour Trips	750 Daily Trips
Residential: Single Family	150 units	70 units
Apartments	245 units	120 units
Condos/Townhouses	295 units	120 units
Mobile Home Park	305 units	150 units
Shopping Center	15,500 sq. ft.	2,700 sq. ft.
Fast Food Restaurant (GFA)	5,200 sq. ft.	1,200 sq. ft.
Convenience Store w/ gas (GFA)	1,300 sq. ft. or 5 pumps
Bank w/ Drive-In	4,400 sq. ft.	2,800 sq. ft.
Hotel/Motel	250 rooms	90 rooms
General Office	55,000 sq. ft.	45,000 sq. ft.
Medical/Dental Office	37,000 sq. ft.	26,000 sq. ft.
Research & Development	85,000 sq. ft or 4.5 acres	70,000 sq. ft or 4 acres
Light Industrial	115,000 sq. ft. or 8 acres	115,000 sq ft. or 11.5 acres
Manufacturing	250,000 sq. ft.	195,000 sq. ft.

There are basically four methodologies used to determine traffic generation of new developments. The Institute of Transportation Engineers describe the methods within their documents. A and B bullets are the most often used throughout the world, while bullet C is sometimes used when there is no money in the budget for a survey to be conducted. Bullet D is rarely used due to the high cost of the study.

A ►Traffic generation rates for similar types of developments in the project area are determined by conducting local surveys and then traffic generation rates per unit area are calculated proportionately for the proposed development.

B ►Traffic generation rates from a similar area are assumed as applicable to the proposed study.

C ►If there is an absence of locally derived rates, by referring traffic generation rates published by the Institute of Transportation Engineers; appropriate rates are obtained according to the area of development.

D ►Using regression analysis of data obtained by surveys for number of developments of different sizes in the same area, the corresponding traffic generation rates are obtained.

With all four of the above methods, there are 6 assumptions that are established for every site impact study, in addition to any other assumptions applied to the specific study.

■Traffic generation rate can be expressed in terms of land use units that were used as activity measure.

■The traffic generation rates are related to one or two independent variables and mostly only the activity per land use unit.

■The generated traffic by new developments is considered as purely new trips that did not exist prior to new development.

■In the case of commercial centers, all of the shopping trips are assumed as primary trips.

■Peak period of the development is mostly considered as critical and therefore used for analysis.

■Traffic generation behavior is generalized and rates derived for other developments are very often used. In other words, site-specific nature has been overlooked in most cases.

Of course the traffic impact analysis is not a perfect science and real life factors always come into play which is hard to truly predict and or too time consuming (expensive) to study, therefore it is just an estimation as the 6^th bullet states for the assumptions listed above. Some of the more obvious problems with these studies include:

-A better estimation of trips made from a residential area would be to count the number of residents, cars owned and income level of the residents of each dwelling. The count of dwelling units in a particular area is primarily used, due to the ease of use and the fact the information is readily accessible.

-Assumption of new trips generated by a new commercial development such as shopping centers, when truly the trips are just to and from the new shopping center. Not a new trip just a different trip.

-Traffic generation rates are usually only generated using one or two independent variables, again due to the readily available information. Traffic generation is actually affected by many variables such as types of activities at the specific site, accessibility to the site, distance and size of similar sites in the area, condition of connecting road networks to those similar sites, many other factors. Many current modeling techniques ignore these factors.

-Other and sometimes even harder factors to predict are qualitative rather than quantitative. These factors can drastically impact the volume of traffic attraction compared to another similar development in the local area.(If the development site is a business or center of some kind) Some qualitative factors include:

Generally, Traffic generation is site specific. The site impact traffic estimation is at best a rough gauge of how the local impacted traffic situation will really be.

Meyer M D& Miller E J (2001) Urban Transportation Planning 2^nd edition. New York: McGraw Hill

As our economy turns to become more global the amount of imported items continues to grow. Port traffic in the last twenty years has grown considerably. In addition to more port traffic there is more truck traffic on America’s highways too. There is a great need for cities to do more studies on freight traffic, so that freight can move more efficiently.

As technology has developed over the past decade, there have been many new developments for data collection referring to freight.

New data collected is same as old data, although data is collected faster and with a greater amount of detail.

Demand Estimation- Methods that can be used to derive quantitative estimates of demand.

Comparison Studies, Aggregate behavior studies, Sketch plan method, Discrete choice models, Regional travel models.

Relative Demand Model- Methods that do not predict actual demand levels but which can be used to assess potential demand for, or relative levels of, non motorized travel.

Supply Quality Analysis- Methods that describe the quality of non motorized facilities rather then the demand for such facilities; these may be useful for estimating demand if demand can be related to the quality of available facilities.

Supporting tools and techniques- analytical methods to support demand forecasting

Since freight carriers are larger then cars, there is a special way of classifying there impact on the road. Commercial vehicles have a large impact on congestion especially in cities and aerially highways. That is why there is a special model freight vehicles and it is called Passenger car equivalent.

PCE x number of that type on road = resulting values are assigned to highway network

In Baltimore at the intersection of Boston and Clinton in Canton, is an intersection that receives more then normal truck traffic because of the City of Baltimore’s Port is located near by. A senior citizen home is being built on the corner of the intersection. There will be increased usage of pedestrian traffic. So the city set out to make the intersection friendlier to those who will be crossing the road and those who will be traveling on the road.

The intersection contains cut out on Boston Street for turn lanes. Boston Street is classified as a 4 lane divided road while Clinton Street is a 2 lane road. The major problem for truck travel is that those on Clinton road need to get on Boston Street.

After the study was completed it was found that there was a problem. Although fixing the problem would be hazardous to the pedestrians because the corners would need to be cut so that trucks could enter Boston Street more easily.

Tim Blakely

Bicycle and Pedestrian Transportation, Traffic Calming and Parking

Introduction: The most basic form of transportation is walking. In congested urban areas, walking is often the quickest for of transportation. Bicycling, according to a study at MIT, is the most energy efficient form of transportation that has ever existed. This study found that the bicycle has an energy equivalent of 1,500 miles per gallon. There are several methods used universally throughout the country to influence the calming of traffic as well as aid in the parking needs of motor vehicle users.

History of bicycles and transportation: Over 100 yrs ago the bicycle was introduced as a form of transportation as well as recreation.

$ Once automobiles were introduced the use of bicycles rapidly declines in the United States.

$ The 1960's saw a comeback of the bicycle as a valid form of transportation and recreation.

$ The 1970's was the era when cities began to separate bikes from cars by means of bike paths in order to reduce the number of fatal conflicts.

$ Today bikes and cars share the road in most areas of the United States.

$ Most cities are attempting to improve the roadway conditions and designs to better accommodate cyclists.

History of walking as a form of transportation: Walking is our original and most basic form of transportation.

$ As people continue to move away from urban areas walking is further decreased.

$ Walking has recently been making a slow comeback due to the fact that it is being promoted as a health benefit.

Benefits of bicycling and walking:

$ Reduction of traffic congestion

$ Reduction of air and noise pollution

$ Less wear and tear on roadways

$ Petroleum is preserved

$ Reduction of crashes resulting in expensive property damage

$ Less of a need for additional lanes, roads and parking

$ Improves the health of the walker or cyclist

$ Much more cost efficient

Communities that support walking and cycling have benefits beyond transportation:

$ Many cities throughout the country have experienced economic benefits by enhancing non-auto transportation. Businesses benefit from improved access and an environment that is more friendly towards people strolling down a street and window shopping.

$ The presence of pedestrians and cyclists in a city indicates the sense of community is strong and gives off the feeling of being very safe to travel outdoors.

$ This ease of traveling by foot or bicycle also aids in tourism allowing tourists to travel without the need for an automobile. An excellent example of this is Baltimore’s inner harbor area.

The most effective walking and bicycling paths are best achieved by modifying existing street systems because:

$ The system is already in place

$ Streets take people where they want to go

$ Streets travel to places of business, homes, shopping areas, etc.

Incentives may be offered to help influence people to travel by foot or on a bicycle: People traveling in this manner are often at a disadvantage because they are exposed to the elements, travel on roads often designed primarily for motor vehicles, have inadequate storage areas for bicycles, etc. To help encourage greater use, incentives may include:

$ Financial incentives such as tax breaks

$ Facilities such as secure bicycle parking, showers and changing rooms

$ Work schedules that allow commuters to travel during daylight hours

$ Relaxed dress code

$ Guaranteed ride home from a taxi for emergencies when walking and cycling are not practical

Design:

Bike lanes:

1.) Establish the correct position of bicyclists on the road.

2.) Provide bicyclists an area to travel at their own rate of speed next to motorists

3.)Send a message to motorists that bicycles have a right to be on the road

Walkers: Transportation planners sometimes implement a “planting strip” alongside a roadway. A planting strip is a small strip of land that runs between the road and the walkway and contains trees and shrubs. The planting strip:

$ Acts as a buffer for noise and road debris

$ Adds a more pleasant feeling to walking alongside a busy roadway

Troubles with improving bike and pedestrian roadways:

$ The main problem with creating and restoring bikeways is a lack of funds.

$ In most areas of the country bicycle and pedestrian commuting is not a top priority for city planners.

$ Recently cities are beginning to discover the benefits of having these alternative modes of transportation and are slowly implementing them.

$ Making urban streets more inviting to cyclists and pedestrians also requires that adjacent land use, traffic speeds, transit access and street connectivity are considered in urban designed.

$ In many areas ,these urban designs have been in place for many years which creates problems of being able to find room to add on another lane specifically for cyclists. This is also an issue dealing with money. Many people feel it is not necessary to widen a road only to add a lane for cyclists.

$ Some areas had been developed before bicycles and walkers were considered part of the transportation planning process. These roads have little to no shoulder with businesses lining the street on both sides. This allows for very little room to widen a road to accommodate cyclists and walkers.

Traffic Calming Definition: The actual definition of traffic calming varies depending on which organization is defining the term. All definitions share the common goals of reducing speeds, improving safety, and enhancing the quality of life.

$ Montgomery County’s definition: Traffic calming consists of operational measures such as enhanced police enforcement, speed displays, and a community speed watch program, as well as such physical measures as edgelines, chokers, chicanes, traffic circles, and(for the past four years)speed humps and raised crosswalks.

History of traffic calming in the U.S.: The U.S. began practicing traffic calming during the late 1960's and early 1970's. The first national study of traffic calming was seen in 1980. It explored residential preferences related to traffic, collected performance data on speed humps, and reviewed legal issues. In 1998 the Federal Highway Administration funded another study which led to a report titled, Traffic Calming: State of the Practice. Unlike the 1980 report this report went beyond residential streets to include major thoroughfares.

Measures used to aid in traffic calming: Speed humps, raised crosswalks, raised intersections, textured pavements, traffic circles, roundabouts, realigned intersections, and center island narrowing.

Troubles associated with traffic calming: The most common problem associated with traffic calming is the accessability of emergency vehicles. Many traffic calming measures used to slow traffic speeds also slow the speed of emergency vehicles.

Parking: Parking is one of the most basic needs of automobile users. The goal of planners is to provide enough parking to meet an areas needs without providing too much as to discourage other modes of transportation.

$ Parking involves both city and private organizations. Both decide the cost and time limit of parking spaces. Cities control the amount of parking spaces provided by private organizations through the use of zoning regulations.

$ Changing the way on street parking is used such as increasing turnover time of parking spaces by increasing the number of meters or time limit signs.