Chapter 5: Traffic Signal Projects

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Section 1: Overview

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Introduction

This chapter explains traffic signal project funding and programming, methods of construction, submission requirements, and project construction. The submissions consist of information gathered during the traffic study and include various forms, graphs, sketches, plans, and other justification data.

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Division Responsibilities

The Traffic Operations Division (TRF) has primary responsibility for reviewing projects solely involving traffic-related work such as the installation of traffic signals. This responsibility includes contract PS&E review and process for letting. Contract projects in which traffic-related work accounts for a minor portion of the work are usually the primary responsibility of the Design Division (DES), with review assistance provided by TRF.

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Authorization Request Form

Districts use the Traffic Signals Authorization Request Form to recommend the type of traffic signal control to install at a particular location, the method of accomplishing the work, the warrants upon which the authorization was based, and the funding source. When executed by the district, the form also serves as:

  • authorization for the existence of the signal and
  • authorization to do the work under certain programs where work authority has not been previously granted.

Districts are authorized to program projects directly with the Transportation Planning and Programming Division (TPP). In order to obtain a valid control-section-job (CSJ) number to establish a project, the district must submit a signed Traffic Signal Authorization Form to TPP.

Signature Requirements. The following officials’ signatures are required on the Authorization Request Form:

  • recommendations by district traffic section
  • approval by the district engineer.

Disposition of Paperwork. TxDOT policy requires districts to keep all relevant paperwork in their files. Traffic engineering data need not be submitted to TRF. Only a copy of the signed Authorization Request form needs to be submitted to TRF for permanent filing.

Form Available. A sample Traffic Signal Authorization Request Form is provided in Appendix A of the hard copy print version of this manual. This sample form may be photocopied as necessary. Copies may also be obtained from TRF. In the on-line version of this manual, an MS Word version of this form may be opened and printed out by clicking on the following file name: TFF-TSAR.

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Recommending Against Installation

When the district’s traffic study indicates that a traffic signal is not needed, the district should notify the requesting party, by letter, that a traffic signal installation is not recommended. In unusual cases, the district may wish to submit their traffic study to TRF for review and comment prior to notifying the requesting party of the study results.

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Marginally Warranted Signals

A signal is “marginally warranted” if the traffic study data obtained from the location barely meet the minimum criteria for one or more of the Texas Manual on Uniform Traffic Control Devices (TMUTCD) warrants. The engineer must use his or her judgment to determine if installing a signal at a marginally warranted location would be in the best interest of the traveling public.

Research (Research Report 1350-1F) suggests that signalizing a marginally warranted location in a low speed (less than 40 mph) rural setting can significantly reduce crashes at the location. This is only true if the location has experienced more than 2 crashes per year over the past 5 years and if the location has experienced more than 0.8 right angle crashes per year over the past 5 years. In all other instances, installing a marginally warranted signal could result in a higher number of crashes.

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Removal of Traffic Signals

Although the original installation of a traffic signal may be based on the satisfaction of one or more warrants and other factors, changes in traffic flow over time may reduce the effectiveness of traffic signal control. When this occurs, it may be appropriate to remove a traffic signal. Neither the TMUTCD nor the National MUTCD contain specific warrants for the removal of traffic signals. The only MUTCD guidance relative to signal removal is a statement that a signal should not continue in operation if it does not meet any of the warrants. However, it is possible that a signalized intersection that does not meet any of the warrants will meet at least one warrant after the signal is removed (due to increases in crashes, delay, or traffic patterns). Therefore, the removal of a traffic signal requires engineering judgement.

Due to the expense associated with the removal and possible reinstallation of a traffic signal, the following steps should be followed prior to the removal of a traffic signal:

  1. The traffic signal should be placed in flashing operation reflecting two-way or multi-way stop control, as appropriate.
  2. If, after an extended period of flashing operation, intersection operation and safety is acceptable, the signal should be deactivated and STOP signs should be installed on the appropriate approaches. Signal deactivation can be accomplished by covering the signal heads, turning them face down, or removing the signal heads completely. Signal related signing should be removed from the intersection. The signal poles, mast arms, and span wire should be left in place.
  3. After an extended period of acceptable sign control operation, the signal poles, mast arms, and span wire should be removed.

NOTE: TRF should be consulted for guidance when removal of a traffic signal is being considered.

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City Traffic Signal Installation Using Local Funds

When a city of 50,000 or greater population (latest federal census) desires to install a traffic signal using local funds within its corporate limits on a highway of conventional design which is on the state highway system, TxDOT must conduct a traffic study to determine

  • if there is a need
  • if warrants are met
  • if the proposed installation should be authorized.

When the district engineer approves the project by signing the Traffic Signal Recommendation Authorization Form, the district sends a copy to the Traffic Operations Division (TRF) for permanent filing. The district should then forward a copy of the signed authorization form to the city to serve as their record of approval for the proposed traffic signal installation.

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Project Cancellations or Change

If for any reason the work from an approved project is not to be performed or the method of performing the work is to be changed (such as from state forces to contract or vice versa), the district should advise DES, TRF, and if necessary, the Transportation Planning and Programming Division (TPP).

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