TxDOT’s Access Management Manual and RDM

(

Appendix Q, Section 4 – External References ‘Reference 4’

) is used for driveway spacing and turn lane configuration

Chapter 8 “Freeways” of the RMD has information on developments near freeways that can impact a TIA.

If the future scenario analysis shows high or unacceptable delays, appropriate mitigation measures are taken to correct or alleviate the issues on the roadway network. If a signalized intersection is experiencing unacceptable vehicular delays, phasing and timing settings are optimized to mitigate the delay levels. If signal optimization is not enough to alleviate the vehicular delay levels, improvements to intersection geometry or type are considered. If an unsignalized intersection experiences notable delay, redistribution of trips to other routes is considered.

Review the location of access points on site in relation to existing nearby access points and intersections for safety considerations. It is recommended that the site plan be examined to confirm the design of external access points account for bicycle and pedestrian safety. It is recommended that a safety and crash analysis based on the past five calendar years be conducted within the study area. Compare crash rates for the study area with statewide/municipality crash rates. Identify CRF to mitigate key locations. See

Appendix Q, Section 4 – External References (Reference 6, 7)

for additional information regarding safety analysis for Traffic Impact Analyses. Key safety questions to consider while conducting a safety analysis for Traffic Impact Analyses include:

What is the historical crash analysis in the study area?
What are the existing crash types involving fatalities and serious injuries? Where are those crashes? What road user types are represented in those crashes?
Will the project create additional multimodal conflict points?
Will the project result in increased vehicular speeds?
Will the project lead to longer queues that would affect through traffic and cause speed differentials?
Based on crash estimation methods from the HSM methodologies, will the project potentially contribute to more crashes? Review locations that will be modified by the project and evaluate designs.
What countermeasures would improve safety in the study area? Incorporate them in the project to improve safety.
Is there a safety plan in place for the study area? If so, integrate recommendations from the safety plan in the project
Are the crash rates in the study area above the statewide averages for similar roadways? Identify safety-focused mitigation measures.

Consider right-turn deceleration lanes when there are large numbers of right-turning vehicles into the project site. TxDOT’s Access Management Manual outlines thresholds for right-turn lanes at new site driveways. This may involve ROW purchase at corners. See for the threshold values. An

example

of auxiliary lane analysis is shown in

Appendix Q, Section 3 – TIA Example Problems

.

Left-turn deceleration lanes are typically considered for roadways with raised medians. For undivided roadways, reference the TxDOT RDM for left-turn lane volume thresholds and geometry.

Lengthening of storage lanes

Median modifications are considered for both safety improvements and operational improvements. Traffic and safety analysis is performed to determine locations for directional median openings as an alternative to full access openings

As traffic is increased and redirected based on new developments, any existing traffic signals are analyzed for operational deficiencies as well as placement changes that may help with LOS and traffic flow. Preferable traffic signal spacing is one-half of a mile.

If the future demands along the nearby roadway segments are significantly impacted and the roadway is predicted to operate over capacity, widening can be considered to mitigate the extra vehicular traffic volume. ROW limitations and existing geometries are considered when widening is proposed for a project. Improvements, such as a right-turn lane, may necessitate additional ROW.

Consider traffic signal installation at unsignalized intersections with high or unacceptable vehicular delay. In these circumstances, complete a traffic signal warrant analysis following the process outlined in

Chapter 10

of this manual.

Revised striping

Turning lane restrictions

Consider alternative intersections in place of a typical traffic signal intersection. Alternative intersection analysis can be performed following the process outlined in

Chapter 10

of this manual. Roundabout analysis is presented in

Chapter 12

of this manual.