Glossary of terms used in POPE Evaluations
Commonly used acronyms are given beside descriptions in (brackets)
A
A-weighted decibels (dB(A))
A unit for measuring traffic noise.
Air Quality Management Area
Air Quality Management Areas are locations where a local authority determines that air quality is poor and where the national air quality objectives are not likely to be achieved.
All lane running (ALR)
Motorways that apply technology to control speeds and permanently convert the hard shoulder to a running lane. Emergency areas are available at regular intervals, providing places to stop in an emergency.
Appraisal
The assessment of the impacts of road project which informs our investment decision. It considers all aspects of potential investment options and assesses the relevant associated benefits, costs and risks, to enable decision makers to make informed choices.
Appraisal Summary Table
A summary of the outcomes of the appraisal process.
As-built documentation
Documentation supplied by our contractors confirming the technical specification of what has been constructed.
At grade junction
A road junction where two or more roads cross each other at the same level.
Average Daily Traffic - ((A)ADT)
The average number of vehicles in a 24-hour period for a given link, inclusive of weekends and any bank holidays.
Average Weekday Traffic (AWT)
The average number of vehicles in a 24-hour period for a given link, exclusive of weekends and any bank holidays.
C
Carbon Dioxide equivalent (CO2e)
A unit of measurement used to express the global warming potential of different greenhouse gases as a single, comparable figure based on the equivalent amount of carbon dioxide (CO2).
Case Overview Preparation Application (COPA)
A new data collection system introduced by some police forces for collecting road collision information.
Combined Modelling and Appraisal report (ComMA)
A report summarising how the evidence underpinning the business case has been developed. This includes the data, which was collected, the production of the traffic modelling and its performance, the forecasts generated and the economic value of the forecast impacts.
Collision rate (PIC/hmvm)
It is important to consider Personal Injury Collisions (PICS) in the context of traffic levels. If the amount of travel on our network increased, we expect to see more collisions, even when all other factors remain the same. A collision rate presents the number of collisions (measured in PICs), in the context of the amount of travel (measured in hundred million vehicle miles). This metric helps us understand whether the risk of a collision has actually changed or whether the change in PICs is just a consequence of more (or less) traffic.
Collision Reporting and Sharing system (CRaSH)
A centralised system used by many police forces to record road traffic collisions.
Congestion Reference Flow (CRF)
An estimate of the AADT flow at which the carriageway is likely to be congested in the peak periods on an average day
Controlled motorway (CM)
A motorway that applies technology to control speeds, but retains a permanent hard shoulder.
Counterfactual
An estimate of what would have happened if the scheme hadn’t been implemented.
D
Department for Transport (DfT)
The government ministerial department responsible for the transport network.
Detrunked
The process by which responsibility for a road passes from National Highways to the local highways authority
Design Manual for Roads and Bridges
The design standards relating to the design, assessment and operation of motorway and all-purpose trunk roads in the United Kingdom.
Do-minimum (DM)
The forecast of how the road network would perform if the scheme wasn’t constructed.
Do-something (DS)
The forecast of how the road network would perform if the scheme is constructed.
Dynamic hard shoulder running (DHS)
Motorways that apply technology to control speeds and use electronic signs to temporarily increase capacity by utilising the hard shoulder at busy times. Emergency areas are available at regular intervals, providing places to stop in an emergency.
E
Environmental Information System (EnvIS)
A database used to store information about our environmental assets.
Environmental Assessment
The process whereby the environmental impacts of a project are identified and the significance of the effect of those impacts is reported. The reports are usually presented in either an Environmental Statement or a non-statutory environmental assessment depending on the type of project and planning route followed. Both types of report would include measures to manage and minimise the impacts.
F
Five-years after (5YA )
An evaluation carried out five-year after scheme opening.
Fatal Weighted Injuries
The FWI weights collisions based on their severity. A fatal collision is 1, a serious collision is 0.1 and a slight collision is 0.01. So 10 serious collisions, or 100 slight collisions are taken as being statistically equivalent to one fatality
G
Grade-separated junction
‘Grade-separated’ describes junctions where the traffic flows are separated over more than one level.
H
Handover Environmental Management Plan (HEMP )
A project document that provides information on the environmental mitigation provided by a scheme and guidance on maintenance regimes.
Heritage impacts
Impact of the project on the historic environment including buildings, parks/gardens and archaeology.
Hundred million vehicle miles (HMVM)
Standard measure used to estimate the total distance travelled by vehicles on road network.
I
Incident Cost-benefit Analysis tool (INCA)
A tool used in appraisal to estimate the journey time reliability benefits.
Indirect Tax Revenue (ITR)
The change in revenue to the government resulting from a project’s implementation
Injury Based Reporting System (IBRS)
A system used by police to record collision data, where casualty injuries are recorded and casualty severity then coded from the most severe injury
J
Journey ambience
Journey ambience was a measure of the experience of travelling. This includes traveller care (for example, information and facilities), travellers’ views; and traveller stress factors (for example, perceptions of safety, congestion and reliability). It has now been replaced by the term ‘journey quality’
Journey quality
Journey quality is a measure of the experience of travelling. This includes traveller care (for example information and facilities), travellers’ views; and traveller stress factors (for example perceptions of safety, congestion and reliability). Further information can be found in TAG guidance unit A4.1
Journey time reliability (JTR)
A journey is unreliable if the time taken to travel varies substantially day-to-day and road users cannot be confident in planning how long their journey will take. Improving reliability means allows road users can allow a smaller window of time to make that journey.
K
Killed or Seriously Injured casualties (KSI)
The number of people killed or seriously injured in road traffic collisions. This metric is non-weighted but does not pick up all injuries (slight casualties).
M
Meta-analysis
Periodically we undertake analysis considering an overview of the findings across a sample of projects
Motorway Incident Detection and Automatic Signalling (MIDAS)
A sensor-based network designed to collect traffic data and automatically display variable messaging, including variable speed limits.
Motorway Reliability Incidents And Delays (MyRIAD)
A tool used in appraisal to estimate the journey time reliability benefits.
N
National Traffic Information Service (NTIS)
Service by traffic data such as speed and flow is made available to analysts in National Highways.
National Trip End Model (NTEM)
Owned by the Department for Transport and used to inform the traffic modelling that supports our project appraisal.
Net Present Value (NPV)
The difference between a project's benefits and costs, expressed in monetary terms. A positive NPV means the benefits delivered by the project are greater than the costs.
Noise important area (NIA)
Locations identified by the Government as experiencing the highest noise levels as part of its Noise Action Plan.
NOx
A term used in air quality assessment to refer to Nitrogen oxides. These are a group of gases that are created from burning fossil fuels and commonly found in car exhaust gases.
O
One-year after (1YA)
An evaluation carried out one-year after scheme opening.
P
Personal Injury Collision (PIC)
A road traffic collision in which an injury occurs.
Physical activity
An appraisal topic that considers the health benefits of increased non-motorised travel (e.g. walking and cycling). Further information can be found in TAG guidance unit 4.1
Planning time index (PTI)
Planning Time Index (PTI) is a reliability measure which represents how much additional time a motorist should allow to ensure they will arrive on time.
PM10
A term used in air quality assessment to refer to particulate material less than 10 micrometres in diameter.
Post-opening project evaluation (POPE)
National Highways’ approach to evaluation of road schemes.
Present Value of Costs (PVC)
The cost present in 2010 prices, discounted to 2010 to be comparable with the other monetary values presented in appraisals and evaluations
R
Road Traffic Forecasts (RTF)
Road Traffic Forecasts are Department for Transport long-term projections of road traffic, congestion and emissions for England and Wales.
Route stress
The route stress metric uses the percentage of road capacity that is being used to assess whether congestion is likely to impact on journey time reliability. A value of 100% means that the road is at full capacity.
S
Screenline analysis
Screenline analysis is where traffic volumes on several parallel routes are considered together to understand the traffic impact at a corridor level.
Severance
Severance means where the project causes additional separation of residents from facilities and services they use within their community Further information can be found in TAG guidance unit A4.1
STATS19
A data collection system of police records from incidents on public roads. It is the primary source of road safety collision and casualty information in Great Britain.
Strategic Road Network (SRN)
The network managed by National Highways, comprising of motorways and some A roads in England.
T
Three-years after (3YA)
An evaluation carried out three-years after scheme opening.
Transport Analysis Guidance (TAG)
Published by DfT, this provides information on the role of transport modelling and appraisal. Often referred to as WebTAG.
Transport Users Benefit Appraisal (TUBA)
The TUBA software undertakes the economic appraisal of transport schemes in accordance with the Department for Transport’s TAG Unit A.1 Cost-benefit Analysis.
V
Value for money (VfM)
This refers to the optimal use of resources to achieve the intended outcomes. Something which is ‘high’ value for money provides a better outcome for investment than an alternative which is ‘low’ value for money.
Vehicle hours
An overall measure taking account of both changes in numbers of road users and their journey times.
Vehicle Operating Costs (VOC)
The fuel and other costs borne by the user (such as the wear and tear on vehicles).
W
webTRIS
National Highways’ public-facing website that provides traffic flow data at count sites on the Strategic Road Network.
